Muscle and Cardiovascular System

Question 1

What unit is made up of multiple myofibrils in muscle?

Answer 1

Muscle fiber

Question 2

What is the smallest unit of the muscle (not including sarcomere)

Answer 2

Myofilament

Question 3

What unit is made up of multiple muscle fibers?

Answer 3

Fascicle

Question 4

What is the difference between the sarcolemma and the endomysium?

Answer 4

Sarcolemma: membrane surrounding muscle cell/fiber
Endomysium: CONNECTIVE tissue surrounding muscle cell/fiber

Question 5

List the connective tissues that separate each unit of muscle from innermost to outermost

Answer 5

Endomysium surrounds muscle fiber/cell
Perimysium surrounds fascicle (muscle bundles)
Epimysium surrounds muscle

Question 6

Where are the myonuclei and satellite cells found?

Answer 6

Sarcolemma, membrane surrounding muscle fibers

Question 7

How do skeletal muscles contract or relax in uniform?

Answer 7

1.) Organization in series or parallel
2.) Connective tissue surrounding each component of a muscle come together to form the tendon that connects to bone
3.)

Question 8

What is the main purpose of the sarcoplasmic reticulum in skeletal muscle?

Answer 8

Store protein and calcium

Question 9

What area of the sarcomere marks the beginning and end of a unit

Answer 9

Z disk

Question 10

What parts of the sarcomere make up the I band?

Answer 10

Thin filament, Titin, Z disk

Question 11

What does the A band consist of

Answer 11

Think and thin filaments only (middle of the sarcomere)

Question 12

What does the H zone consist of?

Answer 12

Where the Think filament has no barbs, spans between the M line of a sarcomere

Question 13

What does the M line consist of?

Answer 13

Middle and thick filaments

Question 14

What zone of the sarcomere “disappears” during contraction and why?

Answer 14

The H band disappears due to the thin and thick filaments moving towards the M line there is no place where the portion of the thick filament has barbless area exposed. Thin filaments cover the H zone

Question 15

Describe the sarcoplasmic reticulum and where its located

Answer 15

Membranous, smooth ER
Surrounds each muscle fiber/cell

Question 16

True/False: the sarcolemma and sarcoplasmic reticulum are synonomous

Answer 16

False, the sarcolemma surrounds each muscle fiber
The sarcoplasmic reticulum webs around each muscle sarcomeres and myofibrils

Question 17

What does the triad consist of?

Answer 17

Consists of the sarcoplasmic reticulum and T tubules

Question 18

What two types of receptors are found in the triad?

Answer 18

Dihydropyridine receptors
Ryanodine receptors

Question 19

What do Dihydropyridine receptors do?

Answer 19

Voltage sensors

Question 20

What do ryanodine receptors do?

Answer 20

Calcium release channel

Question 21

What are the two components that make up a thick filament

Answer 21

Myosin and titin

Question 22

List the 7 components of a thin filament

Answer 22

Actin
Troponin
Tropomyosin
Nebulin
Tropomodulin
α-Actinin
CapZ protein

Question 23

What does Desmin do?

Answer 23

Attaches neighboring sarcomeres or sarcolemma

Question 24

___________ __________ are the motor units responsible for movement across thin filaments

Answer 24

Myosin heads

Question 25

What is the purpose of titin?

Answer 25

Tethers myosin filaments to the Z line

Question 26

What does the Tropomyosin do?

Answer 26

Covers the active site of the troponin complex

Question 27

What does Nebulin do in the thin filament?

Answer 27

Protein that sets the length filament at the Z line

Question 28

What does CapZ do?

Answer 28

Helps anchor thin filament, actin, to the Z line

Question 29

What does Tropomodulin do?

Answer 29

In thin filament, found towards center of the sarcomere on the end of the actin filament Regulates length

Question 30

Thin filament is composed of tropomyosin and troponin complexes. What are the supporting units?

Answer 30

Filamentous actin compose another portion of the thin filament. Filamentous actin is made up of Globular actin

Question 31

CapZ is known to help anchor tin filaments to Z line. What other component assists in anchoring actin to Z line?

Answer 31

α-Actinin

Question 32

What do desmin and Dystrophin do on a broad scale?

Answer 32

Anchor sarcomeres to sarcolemma

Question 33

What does Desmin do?

Answer 33

Binds thin filament to Z disk Interacts with α-Actinin and integrates to anchor Z disk to sarcolemma

Question 34

What does Dystrophin do?

Answer 34

Large structural protein that connects sarcomeres to sarcolemma & is important for stabilization of sarcolemma to prevent damage during contraction a

Question 35

In each thick filament, there are 2 heavy chains wrapped together in an α-helix. Describe what the essential light chain and regulatory light chain does.

Answer 35

Essential light chain: breaks ATP into ADP and Phosphate, ATP-ase activity Regulatory Light chain: phosphorylated to promote interaction with thin filament

Question 36

When myofibrils are arranged in Parallel (one one top of the other) what can this indicate about the function?

Answer 36

Movement of the muscle will be advantage in speed, high velocity and quick action

Question 37

Why are myofibrils that are arranged in parallel "Faster"?

Answer 37

They have greater maximum unloaded displacement. While contraction time remains the same for series and parallel arrangement, if displacement is changed, D*T=Velocity

Question 38

When myofibrils are arranged in series (right next to each other sequentially) what can this indicate about the function?

Answer 38

Movement of muscle will be advantaged in strength

Question 39

Why are myofibrils arranged in series greater strength ability?

Answer 39

Because they have greater maximal tension

Question 40

There are three potential actions during muscle contraction: 1.) Shortening 2.) Lengthening 3.) _______________

Answer 40

Isometric

Question 41

What is and where is the sarcoplasmic reticulum

Answer 41

Surrounds the sarcomeres throughout the myofibril and stores Calcium

Question 42

What do the T-tubules (Transverse tubule) do and where are they found?

Answer 42

Continuation of the sarcolemma into the sarcomeres to allow for communication of innermost muscle cell to outermost

Question 43

When sarcomeres contract, what is happening?

Answer 43

The sarcomere is shortening, the thick filaments are pulling the thin filaments to overlap the thick filaments towards the M line. Z line moving towards each other

Question 44

From where to T-tubules come from and how to they communicate?

Answer 44

T-tubules are an invagination of the sarcolemma surrounding the myofibrils that allows communication into the sarcomere

Question 45

What does DHPR do and where is it found?

Answer 45

Senses when an action potential is moving along T tubule Found in the T tubule in the triad

Question 46

Where is the RyR found and what does it do?

Answer 46

In the sarcoplasmic reticulum of the triad that is a calcium release channel

Question 47

What are the 4 components of force modulation?

Answer 47

1.) Twitch to Tetanus 2.) Neural feed back 3.) Mechanical length 4.) Speed

Question 48

When muscle fibers are aligned in same direction as origin and insertion in parallel:

Answer 48

All muscle fibers and sarcomeres are aligned in same direction as force production

Question 49

What are pennate muscles?

Answer 49

When muscle fibers/cells are NOT arranged in same direction of force production, aligned at an angle of force production

Question 50

Describe the arrangement of the unipennate muscle.

Answer 50

The muscle fibers are all aligned in same direction, BUT at an angle with respect to direction of force production

Question 51

Describe the arrangement of the bipennate muscle

Answer 51

Muscle fiber/cell orientation exists with 2 different angles with respect to direction of force production

Question 52

What is the purpose of having pennate muscle fiber arrangement?

Answer 52

Allows more myofibrils to be compacted into a muscles that amplifies muscle strength Limits length of contraction

Question 53

Pennation produces: 1.) 2.) 3.)

Answer 53

Working range Optimal length Maximal force

Question 54

Muscles that are optimized for force production will have what type of pennation angles

Answer 54

Multiple different pennation angles

Question 55

What is happening to the sarcomere during shortening muscle action?

Answer 55

Sarcomeres are shortening

Question 56

What is happening in an isotonic muscle shortening?

Answer 56

Shortening against fixed load

Question 57

What is happening during isometric muscle action?

Answer 57

Myosin heads are cycling, not length change rather force production ie. pulling on rope tied to a tree, with more pull there is higher tension

Question 58

What is happening during lengthening muscle action?

Answer 58

The myosin heads are trying to pull the thin filaments towards the center but opposing force is to great to overcome. Actin filaments of thin filaments are being pulled apart that can cause injury due to excess strain

Question 59

Changing the stimulus rate in force modulation of muscles is AKA: 1.) 2.)

Answer 59

1.) Temporal coding/summation 2.) Twitch-tetanus switching

Question 60

A stimulus frequency of muscle that allows for complete contraction and relaxation is known as:

Answer 60

Isometric contraction that creates tension Twitch

Question 61

When stimulus frequency is increased, what happens to muscle? This is known as: 1.)

Answer 61

There is greater force production with each stimulus as the muscle is not able to completely relax before contracting again Temporal summation

Question 62

Past temporal summation (increased frequency generating doubled force), there is unfused tetanus. What is happening?

Answer 62

Rapid rise in force production & some slight recovery between contractions because some Ca+ requesting allowed with overall plateau

Question 63

What is fused tetanus?

Answer 63

The fastest frequency stimulation with great force production that plateaus, constant contraction, does not allow any Ca+ resequestering, so tension is constant

Question 64

Different isozymes in muscles can impact the phenotype of muscles. How does this relate to Fast-twitch and Slow twitch muscles and temporal summation?

Answer 64

Fast twitch muscles tetanize at lower stimulation frequency compared to fast twitch muscles that tetanize at higher frequency This allows for longer duration of contraction of slow fibers compared to fast twitch muscles that generate greater forces and higher speed of contraction

Question 65

What is the physiological difference between slow twitch and fast twitch muscles

Answer 65

Fast twitch have large diameter and have greater quantity of fiber motor units compared to slow twitch Different isozymes of light and heavy chains, and SERCA

Question 66

Where do neurons from the CNS attach to the muscle and tendon?

Answer 66

Muscle: muscle spindles/intrafusal fibers Tendon: golgi tendon organs Both providing communication to and from CNS

Question 67

What do muscle spindles do?

Answer 67

Run parallel to muscle fibers and assess the degree of stretch and speed of contraction

Question 68

What do golgi tendon organs do?

Answer 68

They detect the tension exerted by muscle

Question 69

A single motor neuron innervates ___ sets of:

Answer 69

1 set of muscle fibers that respond based on activation history

Question 70

Fast twitch muscles are going to contain large stores of phosphocreatine and glycogen. Why?

Answer 70

Because these can be used in anaerobic metabolism for APT synthesis during short and fast muscle activity

Question 71

Why are there larger stores of glucose, fatty acid and amino acids in slow twitch muscles?

Answer 71

They can be used in aerobic metabolism for APT synthesis which is more sustainable energy source

Question 72

What type of motor neuron recruitment threshold would be associated with fast twitch muscles?

Answer 72

High, when trying to gauge highest level of force production

Question 73

What type of motor neuron recruitment threshold would be associated with slow twitch muscles

Answer 73

Low since they will be more chronically active

Question 74

T/F: muscles either have oxidative or glycolytic metabolism.

Answer 74

False. some fast twitch muscles have capability for both Type IIa for example has both

Question 75

Slow twitch muscles are AKA

Answer 75

Type I

Question 76

Fast twitch muscles are AKA

Answer 76

Type II a & Type II b

Question 77

Type IIb muscles are white in appearance and have fewer mitochondria, why?

Answer 77

Because they rely purely on oxidative metabolism which does not require mitochondria and are white due to low myoglobin

Question 78

What is the difference between spatial summation and temporal summation for muscles?

Answer 78

Spatial summation: gradual recruitment of more and more motor units Temporal summation: twitch vs. tetanus based on increased frequency

Question 79

At low intensity, ________ twitch fibers are recruited. As intensity increases, _____________ fibers then _______ fibers are recruited. This is known as:

Answer 79

Slow twitch Type II A units Type II B units Henneman size principle

Question 80

Describe the difference between temporal summation and spatial summation in terms

Answer 80

Spatial summation: starting with the smallest motor units, progressively larger units are recruited with increasing strength of muscle contraction allow smooth increase in muscle strength with Type IIb units active at relatively high force output Temporal summation: rate of stimulation is modified to increase force production, moving from twitch to tetanus

Question 81

When measuring tension at a given muscle length, the contraction is considered:

Answer 81

Isometric

Question 82

What is L₀?

Answer 82

The length where optimal overlap of thin and thick filament occurs and sarcomere is generating optimal force

Question 83

What are the passive components of tension force? What do they do?

Answer 83

Part of the sarcomere that is not engaging in active cross bridge cycling These passive components generate exponential force as muscle is stretched important counterbalance to active components of force

Question 84

In an isometric contraction, the __________ forces are generated where there is no change in length. Explain what is happening on the sarcomere

Answer 84

Highest Here the myosin heads are generating force by attaching and reattaching on similar areas, since there is no change in length the force generated is tension

Question 85

The highest rate of muscle shortening occurs when? Explain what is happening on the sarcomere

Answer 85

There there is no opposing load/force so velocity is greatest Here since the length is changing, the myosin heads are allowed to slide and change with no resisting forces and fast

Question 86

What is special about the myosin heavy chain isoforms on fast twitch muscles?

Answer 86

They are much faster in shortening via cross bridge cycling the sarcomere, thus contract faster

Question 87

Where does maximal power occur on muscles generally speaking? When considering a mix of slow and fast twitch fibers, where does maximal power occur?

Answer 87

When there is intermediate load, When velocity is half maximal

Question 88

High power fiber outputs are done by:

Answer 88

Fast twitch fibers because they have greatest velocity but use a lot of ATP

Question 89

Low power fiber outputs are done by:

Answer 89

Slow twitch fibers that have optimal power at lower velocity but are sustainable

Question 90

If there is no "load" on a muscle, what does that mean?

Answer 90

There is no opposing force that prevents the myosin heavy chain from pulling thin filament towards M line

Question 92

Power= ____/_____ OR ___f x ____

Answer 92

Work/time or Force x velocity

Question 93

Eccentric contractions are:

Answer 93

Lengthening

Question 94

What are the two most basic type of skeletal muscle fibers?

Answer 94

Fast and slow twitch

Question 95

What is a major component of cardiac myofibers that differs from skeletal myofilament

Answer 95

Intercalated disks separates fibers, butmyofibers at in SYNCITIUM

Question 96

What physically connects cardiac myofibers to one another?

Answer 96

Desmosome

Question 97

What electrically connects each cardiac myofiber to one another?

Answer 97

Gap junctions aka Connexons

Question 98

T/F: Since sarcomeres are the same in cardiac and skeletal muscle, then both have the same composition of T-tubule and sarcoplasmic reticulum

Answer 98

False, the cardiac muscle T tubules and sarcoplasmic reticulum aren't as developed compared to skeletal muscle Cardiac muscle T-tubule forms Dyad instead of triad

Question 99

T/F: Skeletal and cardiac muscle have the same quantity of mitochondria due to the high energy requirement

Answer 99

False, cardiac requires more and has more mitochondria and uses more ATP since they are constantly working

Question 100

Cardiomyocytes rely heavily on the oxidation of _______ for functioning

Answer 100

Fats

Question 101

What component of cardiac muscle that allows for coordinated myofiber movmement?

Answer 101

Gap junctions

Question 102

Describe the depolarization and refractory period of Guinea pig atrium

Answer 102

1.) There is fast depolarization to activate cell 2.) The absolute refractory period is long which disallows repeated simulation of the heart

Question 103

What does phospholambin do?

Answer 103

Inhibits CERCA to disallow pulling Ca+ back into the cell for contraction

Question 104

What is the difference between cardiac muscle & skeletal muscle in terms of Ca+ stores and why is it important

Answer 104

Cardiac muscle not only relys on internal Ca+ supply but also extracellular calcium via DHPR channel and Na/Ca+2 pump. This gives cardiac muscle extra reserves to elicit maximal contraction

Question 105

What is the difference between skeletal muscle and cardiac muscle in terms of the DHPR and RyR channel?

Answer 105

Skeletal: DHPR and RyR channel are directly connected Cardiac muscle: DHPR and RyR channel not directly connected

Question 106

Explain how the action potential reaching the DHPR effects skeletal muscle.

Answer 106

Electromechanical coupling: DHPR changes conformation when AP stimulates which results in mechanical change/opening of ryanodine release channel inside muscle to allow release of Ca+ from the sarcoplasmic reticulum

Question 107

Explain the Electrochemical coupling of Ryr and DHPR channels in cardiac muscle:

Answer 107

Electrochemical coupling: DHPR is activated after action potential, the permeability to Ca+2 is increased and extracellular calcium flows in through the DHPR pore and diffuses to the RyR channel The extracellular Ca+2 signals the RyR to release Ca+2 from sarcoplasmic reticulum

Question 108

RyR and DHPR action: Cardiac muscle: ____________ coupling Skeletal muscle: _______________ coupling

Answer 108

Electrochemical coupling Electromechanical coupling & directly connected

Question 109

Name an L-type calcium channel

Answer 109

DHPR

Question 110

The electrochemical coupling of cardiac muscle in terms of DHPR and RyR is also known as:

Answer 110

Calcium-induced calcium release due to the extracellular calcium inducing release of calcium stores into cell

Question 111

T/F: Skeletal muscle requires extracellular Ca+2

Answer 111

False, cardiac muscle requires external calcium

Question 112

What happens if you place skeletal muscle in Ringers solution (solution heavy in Ca+2)? What about cardiac muslce?

Answer 112

In skeletal muscle, nothing since it does not rely on external calcium In cardiac muscle, it can induce contraction since the external Ca+2 induces release of Ca+2 from RyR

Question 113

Isometric force is AKA

Answer 113

Tension, since there is no change in length but the myosin heads are still contracting

Question 114

What is active force?

Answer 114

The force generated by cross bridge cycling where there is maximum active tension

Question 115

Compare passive force vs active force in cardiac muscle

Answer 115

Passive force: high and exponential Active force: narrow where peak force is not symmetric, once beyond a certain sarcomere length there is a sharp drop in active force production

Question 116

What happens to force type in skeletal muscle when stretch sarcomere length past approx 2.7 mm?

Answer 116

The passive force increases exponentially due to muscle starting to pull back and counter act the force pulling sarcomere apart

Question 117

In terms of length, what is a major difference between skeletal and cardiac muscle active force?

Answer 117

The skeletal muscle has a much wider length at which there is active force (1.4-2.8 um) compared to cardiac where active force is greatest about 2.4 mm on a scale of 1.9-2.6 um

Question 118

What type of force is being produced in cardiac muscle during diastole?

Answer 118

Passive force as heart is passively filling with blood while the filling is spacing out the sarcomeres creating tension for muscle to oppose

Question 119

What type of force is being produced in cardiac muscle during systole?

Answer 119

Active force as heart is shortening and contracting sarcomere length and getting shorter

Question 120

Preload is AKA

Answer 120

End Diastolic Volume

Question 121

What is End Diastolic Volume?

Answer 121

Heart is filled with blood and waiting to contract

Question 122

What is the isometric phase in cardiac cycle?

Answer 122

Preload, the force that must be overcome before ejecting blood from the ventricle during systole

Question 123

What is the isotonic phase of cardiac cycle?

Answer 123

Afterload, the force required to expel the blood opposes the preload

Question 124

At a given preload, the velocity of shortening for cardiac muscle becomes ____________ with lower ________ _______( __________ __________)

Answer 124

Greater After load (opposing force)

Question 125

At a given after load: the velocity of shortening cardiac muscle becomes _____________ with a greater _____________

Answer 125

greater preload

Question 126

Where does actin linked regulation occur?

Answer 126

Cardiac muscle

Question 127

Why does cardiac muscle use actin-linked regulation?

Answer 127

Because a single action potential does not result in maximal force due to cardiac myocytes not having large stores of Ca internally But can reserve Ca is external is given to increase force production

Question 128

Define contractility:

Answer 128

Change in force at a given sarcomere length

Question 129

What do ionotropic agents do?

Answer 129

Affect contractility of cardiac muscle

Question 130

What do positive ionotropic agents do?

Answer 130

Increase Ca in cardiac muscle, inc Contractility 1.) opening Ca channels 2.) inhibiting Na/Ca exchange 3.) Changing Ca stores 4.) Inhibiting Ca pump

Question 131

What do negative ionotropic agents do?

Answer 131

Decrease Ca in Cardiac muscle, decrease contractility 1.) Ca channel blowers 2.) lowered Ca 3.) Higher extracellular Na

Question 132

During preload: Increasing contractility will, increase __________ force and:

Answer 132

Active force total force

Question 133

During afterload: increasing contractility will _____________ velocity

Answer 133

Increase

Question 134

What is the basic mechanism of terminating muscle contraction

Answer 134

Re-Sequestering Ca by SERCA into the sarcoplasmic reticulum

Question 135

In cardiac muscle, terminating contraction, what role does phospholamban play?

Answer 135

Inhibits calcium pump

Question 136

Which valve connects the Right atrium and Right ventricle

Answer 136

Tricuspid

Question 137

The left heart supplies what?

Answer 137

The systemic circuit

Question 138

The right heart supplies what?

Answer 138

The pulmonary circulation

Question 139

What connects the L atrium and L ventricle?

Answer 139

Mitral valve (bicuspid)

Question 140

Where is the pulmonic valve found?

Answer 140

Between the Right ventricle and pulmonary artery

Question 141

Where is the aortic valve found?

Answer 141

Between the Left ventricle and aorta

Question 142

List the 5 requirements of effective heart operation

Answer 142

1.) Contraction at regular intervals and synchronous (no arrythmia) 2.) Valves must fully open (not stenotic) 3.) Valves may not leave ( no regurgitation) 4.) Contractions must be forceful 5.) Ventricles adequately fill during diastole

Question 143

When discussing diastole and systole, what part of the heart is being referred to?

Answer 143

Ventricles

Question 144

Why is the heart considered a dual pump?

Answer 144

2 sided, one supplying systemic circulation, the other supplying pulmonary circulation

Question 145

The systemic circulation is linked in __________ with the left heart pump

Answer 145

Series

Question 146

The pulmonary circulation is link in ____________ with the right heart pump

Answer 146

Series

Question 147

The systemic circulation can change the amount of blood flowing to a body system based on its need. I.e. during exercise, skeletal muscle will receive more blood than GI system. This is all due to:

Answer 147

The systemic circulation disseminates blood via parallel arrangement

Question 148

Resistance in series is:

Answer 148

Summative Rtotal= R1 + R2 + R3 + etc.

Question 149

Resistance in parallel is:

Answer 149

Inverse of total resistance 1/R total = 1/R1 + 1/R2 + 1/R3

Question 150

How does the systemic circulation arrangement allow for independent relation of blood flow to each organ?

Answer 150

Parallel arrangement Total peripheral resistance does not change when organ systems increase/decrease blood flow to an individual portion

Question 151

List 7 parameters affecting hemodynamics

Answer 151

1.) Individual blood vessel diameter 2.) Mean blood flow velocity 3.) Total cross sectional area 4.) Blood volume distribution 5.) Total peripheral resistance 6.) Mean blood pressure

Question 153

Where is the largest total cross sectional area found?

Answer 153

Capillary

Question 154

Where is blood flow velocity greatest?

Answer 154

Aorta

Question 155

Why is velocity slow at the capillary?

Answer 155

Slowed down for exchange of nutrients, waste and gases

Question 156

Where is mean blood pressure highest?

Answer 156

Aorta

Question 157

In circulatory system, as the total cross sectional area gets larger, the velocity:

Answer 157

Gets Smaller/slower

Question 158

What physical changes can be made to reduce resistance in vessels

Answer 158

Increase vessel diameter, and vice versa

Question 159

Where is the lowest resistance in circulatory system?

Answer 159

In capillary

Question 160

Where is the greatest residual resistance found? What is happening?

Answer 160

Arterioles As blood exits the arterioles, the expansive network of parallel capillaries allows drop in resistance

Question 161

At rest, low pressure __________ contain the majority of the systemic blood volume and called the ______________vessels

Answer 161

Vessels Capacitance vessels

Question 162

What is transmural pressure?

Answer 162

The pressure difference across a blood vessel wall. The blood exerting pressure from the lumen (internal pressure, Pi) and pressure being exerted from outside the vesssel (Po)

Question 163

How is Transmural pressure calculated?

Answer 163

Transmural pressure= Pi-Po Inside pressure of vessel - pressure being exerted on pressure

Question 164

Why is transmural pressure important?

Answer 164

Influences vessel diameter The pressure that is being measured by a cuff

Question 165

What is the driving pressure?

Answer 165

The pressure driving blood flow from HIGH to LOW pressure

Question 166

What must occur for driving pressure to occur?

Answer 166

P2 must be lower than P1 to allow flow from high pressure to low pressure

Question 167

Ow do you calculate Driving Pressure?

Answer 167

Delta P = P1-P2

Question 168

If calculating Delta P (__________ __________), what would be P1? P2?

Answer 168

Driving pressure P1: Aorta P2: Right Atrium, ~2 mmHg

Question 169

If calculating Delta P in pulmonary system ( ________ ____________) what would be P1? P2?

Answer 169

Driving pressure P1: R ventricle P2: Left atrial pressure ~ 7 mmHg

Question 170

What is the mean pressure of the arteries in systemic circulation?

Answer 170

100 mmHg

Question 171

What is the mean arterial pressure of Arteries in pulmonary circuit?

Answer 171

15 mmHg

Question 172

To calculate driving pressure of systemic circuit and pulmonary circuit, what 2 numbers are needed respectively?

Answer 172

Need Mean arterial pressure for systemic and pulmonary circuit, P1

Question 173

What does the term phasic blood pressure mean in the aorta?

Answer 173

The change of pressure during systole versus diastole

Question 174

What are the 2 ways to calculate mean arterial pressure?

Answer 174

MAP=1/3 systolic P + 2/3 diastolic pressure MAP= Diastolic pressure + 1/3 Pulse pressure

Question 175

How is Pulse pressure calculated?

Answer 175

Systolic pressure-diastolic pressure

Question 176

How do you calculate systemic driving pressure?

Answer 176

Delta Psystemic = P1 - P2, aortic presssure (mean arterial pressure) - Right atrial pressure

Question 177

How do you calculate Pulmonary driving pressure?

Answer 177

Delta Ppulmonary= P1- P2, Mean pulmonary artery pressure - L atrial pressure

Question 178

Why is systemic driving pressure so much higher than pulmonary driving pressure?

Answer 178

Because Systemic circulation is arranged in parallel resistance

Question 179

What is P1 of the systemic circulation? What is the pressure?

Answer 179

P1 is the beginning of the aorta. Pressure is 120/80

Question 180

What is P2 of the pulmonary circuit driving pressure? What is the numeric pressure

Answer 180

Left atrium 5 mmHg

Question 181

What is P1 of the driving pressure in pulmonary circuit? What is the pressure?

Answer 181

Right ventricle 25/8 mmHg

Question 182

What is the P2 of driving pressure in pulmonary circulation? What is the pressure?

Answer 182

P2 is R atrium 5 mmHg

Question 183

What is the P2 of driving pressure of the systemic circulation? What is the pressure?

Answer 183

R atrium 2 mmHg

Question 184

What is calculated using the Nernst Equation

Answer 184

The point where the diffusional gradient exactly balances the electrical gradient

Question 185

Define Equilibrium Potential for a given ion

Answer 185

The membrane electrical potential at which inward flow of that ion is equal to its outward flow

Question 186

Equlibrium potential (Eeq) =

Answer 186

ion concentration inside/ion concentration outside

Question 187

Describe the electrochemical basis of membrane potentials

Answer 187

Ions flow down their concentration gradient but their electrical potential often directionally opposite

Question 188

Describe the ionic gradient for Na+ in cardiac cells. Describe the movement of Sodium based on ionic gradient

Answer 188

Extracellular Na: 150 mM Intracellular Na: 15 mM Outside to In

Question 189

Describe the ionic gradient for potassium in cardiac cells And what direction does the gradient move based on ionic gradient

Answer 189

Extracellular K: 5 mM Intracellular K: 10 mM Potassium In to Out

Question 190

Describe ionic gradients for Calcium in cardiac cells. Describe the direction of calcium movement based on ionic gradient

Answer 190

Extracellular Ca: 2 mM Intracellular Ca: 0.0001 mM Outside to In

Question 191

What type of channels allow more than one type of ion through?

Answer 191

Mixed conductance channels

Question 192

What happens in cardiac ion channels a negative voltages (>70 mV)?

Answer 192

M gates open

Question 193

In cardiac cells, Na+ enters a cell down its concentration gradient-this generates an inward membrane current. What does this cause?

Answer 193

Depolarization

Question 194

What direction to K+ currents move in cardiac cells? What does this do?

Answer 194

Outward movement to make the cell more negative inside (Repolarization)

Question 195

List the 4 different K+ cannel types in cardiac muscle which allow K+ current to flow at vairious times

Answer 195

1.) Inward rectifier 2.) Transient outward K+ current (Ito) 3.) Delayed rectifier K+ currents IKr 4.) Delayed rectifier K+ currents and Iks

Question 196

Describe what a inward rectifier potassium cardiac channel (Kir) does

Answer 196

▪️ Acts as background potassium channel ▪️ Opens at negative voltage and sets the stable negative resting membrane potential that is esp. seen in atrial and ventricular muscle ▪️ -90 mV ▪️ When membrane potential becomes more positive these channels close

Question 197

Describe what transient outward K+ channels (Ito) do

Answer 197

Opens rapidly on depolarization and closes equally rapidly generating transient repolarizing force in ventricals and atrial muscle

Question 198

Describe what the two types of delayed rectifier channels do? Irk and Iks

Answer 198

Closed at negative voltages Open when membrane potential becomes more positive, effectively repolarizing cells Note IKr has a faster activation rate compared to Iks

Question 199

Cardiac potassium channels in the heart all generally move K+ _________________ the cell. Why are there separate types of channels?

Answer 199

All move K++ outside of the cell Have different parameters for opening and closing, work at different times to move potassium

Question 200

What type of channel are predominant in cardiac tissue?

Answer 200

L type Ca+ channel

Question 201

What are the two types of cardiac Calcium channels?

Answer 201

L type and T type

Question 202

Where are T type calcium channels found?

Answer 202

Atrial and pacemaker cells

Question 203

What is another name for T type calcium channels

Answer 203

Tiny conductance & Transient openings

Question 204

Describe T type calcium channels

Answer 204

Open at -55 mV and close fairly rapidly which is why they are called transient

Question 205

T/F: T type calcium channels are found in Atria and pacemaker cells and L type calcium channels are found in ventricles and SA node

Answer 205

False, L type calcium channels are found thoroughout the heart

Question 206

What is another name for L type calcium channels

Answer 206

Large conductance and Long lasting opening channels

Question 207

Describe L type calcium channels

Answer 207

Open at -40 mV and inactivate more slowly compared to T type and depolarizes the membrane becuase of the inward movement of + charge

Question 208

Describe Mixed conductance channels in cardiac tissue

Answer 208

Permeable to Na+ and K+ Activated slowly by Hyperpolarization at -60 mV Driving force for Na influx > K efflux Net inward Na+ movement

Question 209

Where are funny current mixed conductance channels found?

Answer 209

On nodal and purkinje cells

Question 210

What is the importance behind delayed conduction of the atrial excitation and ventricular by AV node

Answer 210

Allows atria to contract before ventricles are excited so atria can fully fill with blood

Question 211

List the intrinsic pacemaker firing rates in order from slowest to fastest in heart

Answer 211

Purkinje system: 20-40 bpm AV node: 40-60 bpm SA node: 60-100 bpm

Question 212

Where does the fastest rate of depolarization occur in cardiac musle?

Answer 212

In the SA node

Question 213

What type of channels are found in Purkinje fibers that allows for slower depolarization?

Answer 213

Funny current channels (mixed conductance channels)

Question 214

If the SA node fails, the AV node can still depolarize, and if both fail the Purkinje system can still function. What property allows firing of action potentials for SA node, AV node and Purkinje system?

Answer 214

Intrinsic function

Question 215

There exists large ______________ directed electro-chemical gradient for Na ions and so when channels open:

Answer 215

Inward brings positive charge into the cell to make less negative

Question 216

What purpose do Potassium channels serve in cardiac cells?

Answer 216

Repolarization, to make inside of cell more negative since potassium is leaving

Question 217

When the SA node is initiating the action potential, what happens to other tissue? What is this termed?

Answer 217

All other tissue activity is suppressed by the SA nodal pacing Termed: overdrive supression

Question 218

What are the two types of action potentials found in the heart?

Answer 218

Fast and slow response

Question 219

The SA and AV node produce ____________ response action potential

Answer 219

slow

Question 220

The cardiac atrial and ventricle myocytes produce the ________________ response action potential

Answer 220

Fast

Question 221

What is happening in phase 0 of fast response action potiental

Answer 221

Depolarization -90 mV towards 0 mV Opening voltage dependent fast Na+ channels End of this phase marked by drop peak of depolarization and followed by quick slight drop in mV

Question 222

What is happening in phase 1 of action potential in fast response

Answer 222

Early repolarization Opening of voltage dependent K+ channels, Na+ channels inactivate Starting to become more negative

Question 223

What is happening in phase 2 of fast response action potential

Answer 223

Plateau phase - Opening of voltage dependent slow L-type Ca channels to balance with slow delayed rectifier K+ cells - influx of Ca+, efflux of K+

Question 224

What is happening in phase 3 of fast response action potential

Answer 224

Rapid repolarization - Closure of L type Ca channels (slow) - K+ channels open open

Question 225

What is happening in phase 4 of fast response action potential

Answer 225

Resting membrane potential Inward rectifier K+ channels open (efflux) to maintain resting membrane potential

Question 226

What two ion channels depolarize cardiac cells?

Answer 226

Na and Ca

Question 227

Why do Na channels act first in an action potential of fast response cardiac cells?

Answer 227

Because they open rapidly compared to L type calcium channels which are more slow to open

Question 228

At the start of phase 4 of fast response action potential in ventricle and atrial mucle, the mV is ~-60 and will continue to drop during this phase. What type of channel opens at -60 mV to ensure continued depolarization?

Answer 228

Delayed rectifier K+ currents and IKr and IKs

Question 229

How many phases are there in fast action potential of ventricle and atrial tissue? How many phases are there in slow response action potential of pacemaker cells?

Answer 229

Fast action potential: 5 phases Slow action potential: 3 phases

Question 230

What is happening during phase 0 of slow response pacemaker action potential?

Answer 230

Depolarization Opening of slow L type Ca channels & thus influx Ca

Question 231

What is happening in phase 3 of slow response pacemaker action potential

Answer 231

Repolarization Opening of delayed rectifier K+ channels, efflux of K Closure of Ca+ channels

Question 232

What is happening in phase 4 of slow response pacemaker action potential

Answer 232

Pacemaker potential (slow depolarization potential) - closure K+ channels - opening funny channels (influx depolarizing charges and net influx Na) - Opening of two Ca channels, transient and L

Question 233

Compare the difference in Na action in fast and slow response action potential of cardiac cells

Answer 233

In fast response, Na plays a large role in quick depolarization In slow response, the mixed conductance channels allow some

Question 234

Compare the starting voltage of slow response action potential compared to fast response action potential

Answer 234

Fast response starts much more negative, -90 Slow response starts about -60

Question 235

In slow response action potential, during slow depolarization, what ion responsible for this? What channels are involved?

Answer 235

Calcium is depolarizing the cell first The T type channels act first to raise calcium levels but L type calcium channels increase Ca levels to a greater extent and push the depolarization past 0 mV

Question 236

The membrane potential in ___________ __________ cells is never stable but changes continuously. Phase 4 depolarizing pacemaker potential enabling ___________ ______ to produce:

Answer 236

SA node SA node produces the rhythmic action potential without any neurological stimulus

Question 237

When the cardiac cells are at REST: how would you describe the charges on surface and internal of each cell

Answer 237

Surface of cells is + Interior of membrane is negative

Question 238

As an action potential passes each cardiac cell, describe what happens to the charge on the surface of the cell

Answer 238

Surface of cell changes from negative to positive

Question 239

The ECG:

Answer 239

Reflects changes in the charge on the surface of the heart

Question 240

How is the ECG able to detect changes in surface of cardiac cells?

Answer 240

The body fluids conduct the charge to the surface of the skin

Question 241

Where does the first change from + to - on cardiac cell surface occur? Why?

Answer 241

On the SA node because it is the first to depolarize

Question 242

T/F: When the SA node is depolarized and cell surface becomes negative, other cardiac cells are following suit at the same time

Answer 242

False, the rest of the cardiac cells are still at rest with - cell interior and + cell surface

Question 243

What is created when the SA node depolarizes and the cell surface becomes negative while the remaining cardiac cells are still at rest and + cell surface

Answer 243

A dipole is created

Question 244

What creates the upward deflection on ECG?

Answer 244

A wave of depolarization moving towards a positive electrode

Question 245

What produces a downward deflection on ECG?

Answer 245

A wave of depolarization moving away from positive electrode

Question 246

How many standard limb leads are there?

Answer 246

3

Question 247

What do the standard limb leads measure?

Answer 247

Lead connects 2 poles, so they measure the electrical activity between the 2 connected poles on the frontal plane

Question 248

Standard limb lead I has a + electrode on: and - electrode on:

Answer 248

L arm +

Question 249

Standard limb lead II has a + electrode on the and - electrode on:

Answer 249

L foot + R arm -

Question 250

Standard limb lead III has a + electrode on: - electrode on:

Answer 250

Left foot + Left arm -

Question 251

What do augmented limb leads record? What makes them different?

Answer 251

Electrical activity on frontal plane through the heart These leads create smaller waveforms that the machine must augment and make larger

Question 252

What is different about the augmented limb leads compared to standard limb leads?

Answer 252

Augmented (aVR, aVL, aVF) only require unipolar and thus only require 1 electrode to make he lead

Question 253

Where is aVF lead?

Answer 253

Left foot

Question 254

Where is aVL lead?

Answer 254

L arm

Question 255

Where is aVR lead located?

Answer 255

R arm

Question 256

T/F: All precordial leads are positive and bipolar and measure on the frontal plane

Answer 256

False, they are all positive but they are unipolar and measure on a transverse plane

Question 257

What is the rhythm strip on an ECG? What is the purpose

Answer 257

An expansion of V1, V5, V6 to Purpose to help identify infrequent abnormalities

Question 258

What is a segment on the ECG

Answer 258

A segment of isoelectric neutrality, flat, no electrical activity

Question 259

Where are intervals on an ECG?

Answer 259

Areas where at least 1 wave of activity is present

Question 260

What is happening during the P wave

Answer 260

Depolarization through the atria The first + upward deflection on EKG Initiates contraction of atria

Question 261

The period of electrical neutrality after P wave is called: What is happening here

Answer 261

PR segment Time required for conduction of action potential though the AV node, Bundle of His and purkinje system to ventricular muscle Depolarization is occurring

Question 262

What is the PR interval? What does it consist of?

Answer 262

Time required for wave of depolarization to move from SA node, AV node, bundle of His and purkinje system Called atrioventricular conduction time Consists of P wave an PR segment 0.12-0.2 seconds

Question 263

What interval on EKG might change during increased heart rate? Or lengthens when heart rate decreases?

Answer 263

PR interval

Question 264

What might be occurring when the PR interval is >0.2 seconds?

Answer 264

Conduction block in AV node

Question 265

What is the QRS interval?

Answer 265

Reflects the time of depolarization through the ventricular cardiomyocytes Time for ventricular contraction Duration <0.1 seconds

Question 266

During the QRS interval, the ventricles and what else are depolarizing? Why is the focus still on ventricular contraction?

Answer 266

Atria repolarizing but electrical conducting is smaller

Question 267

What is happening during the ST segment?

Answer 267

Ventricles completely depolarized Electric neutrality

Question 268

What can it mean when ventricles are elevated or depressed?

Answer 268

ischemic event in the ventricles

Question 269

What is occuring during the T wave?

Answer 269

Represents Ventricular REpolarization

Question 270

Why does the T wave show up as a positive inflection even though this is repolarization?

Answer 270

1.) Repolarization occurs in opposite direction of depolarization in epicardial surface 2.) The direction of ion movement is opposite of depolarization and surface charge of the cells is going from Neg to Pos to produce a positive inflection

Question 271

What is the QT interval? What does this interval envompass?

Answer 271

QRS complex, ST segment, T wave Time required for entire ventricle to undergo one cycle of depolarization and repolarization An entire ventricular systole (contraction)

Question 272

What interval is corresponding to the heart rate?

Answer 272

QT interval

Question 273

What is the normal ratio of QT interval compared to R-R interval?

Answer 273

QT interval is normally less than half the R-R interval

Question 274

What does the TP segment represent?

Answer 274

Electrical neutrality, atrial and ventricular diastole, filling with blood

Question 275

What does the R-R interval represent?

Answer 275

Duration of one complete cardiac cycle/heart beat

Question 276

What does the vertical axis represent on ECG tracing paper?

Answer 276

Voltage

Question 277

What do the smallest boxes on the vertical axis of an ECG trace represent? What about the larger boxes of 5 x 5 grid?

Answer 277

0.1 mV 0.5 mV

Question 278

What does the horizontal axis on ECG tracing paper represent? What time interval are the SMALLEST boxes? What about the 5 x 5 grid boxes?

Answer 278

Time Smallest: 0.04 sec 5 x 5: 0.2 seconds

Question 279

What is the most common way to calculate heart rate on ECG?

Answer 279

Count small boxes between R -R waves

Question 280

How can you calculate an estimate of heart rate from ECG?

Answer 280

Using large 5 x 5 boxes, measuring how many large boxes between R wave peaks Or smallest squares are 60 bpm

Question 281

What is the estimated BPM on EGC if 1 large square between 2 R wave peaks?

Answer 281

300 bpm

Question 282

What is the estimated BPM on EGC if 2 large square between 2 R wave peaks?

Answer 282

150 bpm

Question 283

What is the estimated BPM on EGC if 3 large square between 2 R wave peaks?

Answer 283

100

Question 284

What is the estimated BPM on EGC if 4 large square between 2 R wave peaks?

Answer 284

75 bpm

Question 285

What is the estimated BPM on EGC if 5 large square between 2 R wave peaks?

Answer 285

60 bpm

Question 286

What is the estimated BPM on EGC if 6 large square between 2 R wave peaks?

Answer 286

50 bpm

Question 287

What is the estimated BPM on EGC if 7 large square between 2 R wave peaks?

Answer 287

43

Question 288

What is the normal PR interval?

Answer 288

0.12-0.2 sec

Question 289

What is the normal QRS complex interval?

Answer 289

Less than 0.1 second

Question 290

What is the normal QT interval?

Answer 290

Less than half the R-R interval

Question 291

How are the EKG and cardiac cycle related?

Answer 291

ECG shows electrical events of the heart Cardiac cycle shows mechanical events of the heart Electrical events always precede mechanical events of the heart

Question 292

The P-wave occurs just before:

Answer 292

Atrial contraction b/c electrical activity PRECEEDS mechanical activity

Question 293

The __________ ______________________ begins just prior to ventricular contraction/systole because electrical activity PRECEEDS mechanical activity

Answer 293

QRS Complex

Question 294

The T wave (ventricular repolarization) occurs just before:

Answer 294

Ventricular relaxation/diastole

Question 296

What are the 2 requirements of a normal ECG?

Answer 296

1.) Each P wave followed by QRS complex 2.) HR 60-100 BPM

Question 297

What are the 3 types of AV block?

Answer 297

1.) First degree heart block 2.) Second degree heart block 3.) Third degree heart block

Question 298

What is the basis of AV block?

Answer 298

Preventing or delay impulse at SA Node from entering ventricles

Question 299

Which type of AV heart block has 2 subtypes?

Answer 299

Second degree AV block

Question 300

Where can an AV block occur??

Answer 300

AV node, bundle of His, bundle branches or Purkinje system

Question 301

What is occurring in first degree heart block?

Answer 301

Partial degree block of AV node and conduction to ventricles is partially blocked - slow conduction through AV node down to bundle of his and ventricles

Question 302

What is happening in Mobitz Type I block? What degree of AV block is it?

Answer 302

- Partial heart block of AV node also called Wenchebach block - The impulse is not transmitted through the AV node - Second degree heart block

Question 303

What is happening in Mobitz Type II block? What degree of AV block is it?

Answer 303

- Partial block of the Bundle of His - Second degree heart block

Question 304

What are the 2 criteria for determining first degree incomplete heart block?

Answer 304

1.) PR interval should be more than 0.2 seconds 2.) Sinus rhythm exists (P-QRS-T for every beat)

Question 305

Why is third degree heart block sometimes called complete heart block?

Answer 305

The impulse from SA node or Bundle of His is completely blocked. Impulse does not reach bundle branches or any lowered down

Question 306

If the only abnormality shown on ECG is a prolonged PR interval, what condition is indicated?

Answer 306

First degree AV heart block

Question 307

In second degree heart block:

Answer 307

Not all atrial impulses are transmitted through the AV node

Question 308

In second degree heart block Mobitz Type I , the ____ wave is not followed by __________ complex because:

Answer 308

- As PR interval progressively increases, the conduction through the AV node may fail resulting in a lost QRS complex after P wave - Intermittent conduction failure and loss of ventricular contraction - After the dropped QRS complex, the next impulse is P wave followed by QRS complex

Question 309

Where is the failure of conduction in Mobitz Type I heart block? Where is the failure of conduction in Mobitz Type II heart block?

Answer 309

Mobitz I: AV node Mobitz II: Bundle of His

Question 310

Both first degree AV block and second degree Mobitz Type I (Wenkebach) block involve the AV node, what delineates each other?

Answer 310

In First degree, there is still conduction of ventricles, just delayed at the AV node In Mobitz Type I, the impulse does not reach the ventricles

Question 311

In second degree heart block, Mobitz Type II there is: Mobitz Type II block can lead to:

Answer 311

Sudden unexpected loss of AV conduction and loss of ventricular activation that occurred beyond the AV node Cardiac arrest and/or insertion of pacemaker

Question 312

What is the difference in tracing between Second Degree heart block Mobitz Type I & II?

Answer 312

In type I there is progressive lengthening between P wave and QRS In type 2 there is no wave lengthening on ECG tracing, sudden and not predicable except for ratio between conducted beat and blocked beat

Question 313

T/F: In third degree heart block, there are no impulses transmitted through SA node

Answer 313

False, there are no impulses transmitted through or beyond the AV node so only the atria contract The ventricles contract separately and lower via intrinsic impulse

Question 314

Describe ECG tracing of Third degree heart block

Answer 314

1.) Regular interval, small P waves, 100 bpm 2.) Separately, longer interval QRS complexes, ~ 35 bpm 3.) For every QRS complex generated by ventricle, there are 4 P waves

Question 315

Where in the heart conduction system do sinus bradycardia and tachycardia arise?

Answer 315

In the SA node

Question 316

The ST and TP segments are on the "isoelectric line" in a healthy heart because:

Answer 316

The whole ventricular surface is the same charge

Question 317

ST segment shift (elevation or depression) most often indicates:

Answer 317

a myocardial ischemia or infarction

Question 318

What is the requirement for regular heart rhythm

Answer 318

R to R intervals are the same for each heart beat and the rhythm is maintained

Question 319

A regularly irregular heart rhythm represents a pattern of beats that repeats. Give an example of a regularly irregular rhythm

Answer 319

Second degree Mobitz Type II block since there is a predicable lost QRS complex

Question 320

In an irregularly irregular heart rhythm:

Answer 320

There is no underlying regularity, the R to R interval is completely irregularly

Question 321

During _____________________ the depolarization down the atria or ventricle is so slow that by the time the action potential exits the tissue:

Answer 321

fibrillation a new action potential is already exciting the tissue again.

Question 322

The absence of P waves and irregular R to R intervals with presence of QRS complex on ECG tracing, this indicates

Answer 322

A fib

Question 323

Described as an "undulating baseline," there are no QRS complexes or P waves, and total absence of any pattern on ECG tracing indicates:

Answer 323

V fib

Question 324

In an irregularly irregular heart rhythm:

Answer 324

There is no underlying regularity, the R to R interval is completely irregularly

Question 325

What is the mean electrical axis of the heart?

Answer 325

Tells us direction of electrical condition during during VENTRICULAR depolarization - usually away from R towards Left

Question 326

What are 3 discernable indications made from the mean electrical axis?

Answer 326

- Orientation of heart - Size of ventricular chambers - Conduction block

Question 327

____________________ _____________________ is an equilateral triangle around the heart formed by the three standard limb leads. F

Answer 327

Einthoven's triangle

Question 328

What is the largest interval found on ECG? What does it comprise?

Answer 328

QT Interval Includes: QRS complex, ST segment, T wave

Question 329

What is a normal MEA? What is the exception to this?

Answer 329

Between 0° and +90° Some cardiologists extend to -30°

Question 330

Between what leads is a normal MEA (mean electrical axis)

Answer 330

Between 0 Standard Limb lead I and + pole augmented lead aVF

Question 331

Where is R axis deviation found on MEA? Between what leads?

Answer 331

Between +90° and +150° - pole standard limb lead 1 and + pole augmented limb lead aVL

Question 332

What is indicated if MEA is on R axis deviation?

Answer 332

Normal finding in children, tall thin adults, some athletes R ventricular hypertrophy

Question 333

Where is Left axis deviation found on MEA? Between what leads?

Answer 333

Between 0° and -90° 0 pole standard limb lead I and - pole augmented lead aVF

Question 334

What might be indicated by Left axis deviation on MEA?

Answer 334

Commonly seen in conditions causing Left ventricular hypertrophy Inferior MI R branch bundle block

Question 335

List the 3 ways to calculate MEA What are they focusing on?

Answer 335

Semi Quantitative method Net zero load method Quick Approximation Focus on net direction of aVF and limb lead I

Question 336

How does Semi Quantitative Method determine MEA?

Answer 336

Uses net direction of QRS complexes of the six limb leads (use radial axes)

Question 337

How does Net Zero load method work?

Answer 337

From the net direction of QRS complex of the six limb leads (uses radial axes) Location where Q wave and S cancel each other out Use the lead that forms a right angle with the lead that contains the net zero QRS

Question 338

The "Quick and Dirty" method of MEA determination uses which two leads?

Answer 338

Lead I and aVF (L foot)

Question 339

What determines normal MEA if using the Quick & Dirty method?

Answer 339

Lead I: + Deflection, go to Positive pole aVF: + Deflection, go to + Pole

Question 340

What determines R axis deviation of MEA if using Quick and Dirty method?

Answer 340

Lead I: - deflection, so go to Negative pole aVF lead: + deflection, go to + pole

Question 341

T/F: Each axis for determining the Mean Electrical Axis has a negative and positive pole

Answer 341

True

Question 341

What determines Left axis deviation of MEA if using Quick and Dirty method

Answer 341

Lead I: + deflection, go to + quadrant aVF lead: - Deflection, go to - quadrant

Question 342

What phases of the cardiac cycle comprise diastole?

Answer 342

Phase 1-3

Question 343

When using Wiggers diagram, which part of the heart is being represented?

Answer 343

L side of heart

Question 344

What is the scale of aortic blood flow in the aorta?

Answer 344

0-5 L/min

Question 345

List phases 1-3 during diastole

Answer 345

1.) Rapid ventricular filing 2.) Reduced ventricular filling 3,) Atrial systole

Question 346

What is occurring during diastole

Answer 346

Heart is relaxed, filling with blood

Question 347

What is the longest phase during diastole?

Answer 347

Phase 2, reduced ventricular filling

Question 348

What starts phase I of diastole?

Answer 348

When L atrial pressure becomes greater than L ventricular pressure, this forces the mitral valve to open and allow blood flow into L Ventricle

Question 349

Why do both L ventricle and atrial pressure gradually fall during phase 1?

Answer 349

In atria: blood is leaving, so pressure down In ventricle: when blood is entering ventricle the relaxed state of ventricle to stretch offsets the raised pressure of blood intake

Question 350

T/F: The pressure of the aorta during phase I of diastole is higher than L ventricle pressure which keeps the aortic valve closed

Answer 350

True

Question 351

What is the volume at start and end of phase 1, rapid ventricular filling, of ventricle?

Answer 351

Ventricle start at 50-60 mL and passively fills to ~110 mL

Question 352

Why is rapid ventricular filling in diastole considered PASSIVE filling?

Answer 352

Because the atria is not contracting to expel blood, the pressure gradient is allow blood to flow from High to Low pressure w/o energy input

Question 353

Why does pressure drop in aorta during phase I of diastole?

Answer 353

Because there is no blood flowing into aorta and aorta is emptying while blood flows to peripheral arteries

Question 354

What does the ECG tracing look like during phase I of diastole?

Answer 354

Isoelectric because the heart is relaxed, Between end of T wave and start of P wave

Question 355

Why is ~20 mL of blood flowing from L atria to L ventricle during phase 2 of diastole (reduced ventricular filling)B

Answer 355

Ventricle is reaching its max capacity

Question 356

During phase II of diastole, the L ventricular pressure creeps up as max volume capacity is reach. Why does L atrial pressure slightly increase?

Answer 356

Blood is starting to refill with blood

Question 357

What is happening to the aortic pressure and volume during phase II of diastole?

Answer 357

Pressure continues to drop b/c blood still flowing through peripheral arteries Volume cont. 0

Question 358

What heart sounds may be heard during Phase 2 of diastole?

Answer 358

None

Question 359

What marks the end of phase 2, start of phase 3 of diastole in cardiac cycle

Answer 359

Beginning of P wave to signal atrial depolarization

Question 360

What is the name of phase I of diastole?

Answer 360

Rapid ventricular filling

Question 361

What is the name of phase II of diastole?

Answer 361

Reduced ventricular filling

Question 362

What is the name of Phase III of diastole?

Answer 362

Atrial systole

Question 363

Why do BOTH atrial and ventricular pressure increase during phase 3 of diastole?

Answer 363

Because the atria are contracting, they expel more blood in to ventricle increasing vol and pressure of already filled ventricle

Question 364

Turbulence (sound 4) is created during atrial systole (phase 3 of diastole). Why? Is it normal

Answer 364

Created by blood pushing against ventricle Not often heard

Question 365

T/F: There is blood flow from the L ventricle to aorta during phase 3 of diastole

Answer 365

False

Question 366

What creates the slight increase in venous pressure during phase 3, atrial systole during diastole?

Answer 366

There is light backflow of blood from atria back in to veins

Question 367

T/F: The mitral valve closes after phase 2 of diastole when atria begin to contract

Answer 367

FALSE, the mitral valve closes only AFTER phase 3

Question 368

Aortic pressure steadily _____________________ during diastole. BUT overall, the total pressure is ___________________ than pressure in both atria and ventricle

Answer 368

Decreases greater

Question 370

List the 4 phases of systole

Answer 370

4.) Isovolumic contraction 5.) Rapid Ejection 6.) Reduced ejection 7.) Isovolumic relaxation

Question 371

What is the name of phase 4 of systole

Answer 371

Isovolumic contraction

Question 372

What occurs right before phase 4 of systole?

Answer 372

QRS complex to allow for ventricular depolarization

Question 373

What is the first step of phase 4 of systole?

Answer 373

Ventricles starting to contract which increases pressure such that it is greater than atrial pressure and forces mitral valves closed

Question 374

What sound is heard during phase 4 of systole?

Answer 374

Lub sound created by turbulence of mitral valve closing Sound 1 heard in healthy adults

Question 375

T/F: During isovolumic contraction during systole, the ventricular pressure is so high the aortic valve is forced open

Answer 375

False, the aortic valve is still closed

Question 376

Why is phase 4 termed isovolumic contraction?

Answer 376

The ventricles are closed chambers, both mitral valve and aortic valve are closed while the ventricle is contracting. So pressure is increases but volume has no where to escape to

Question 377

Why does venous pressure increasing during phase 4 of systole?

Answer 377

Because atrial are continuing to receive blood and pressure is transmitted to veins with some backflow

Question 378

What marks the start of phase 5: rapid ejection phase in systole

Answer 378

Aortic valve opens when the ventricular pressure exceeds aorta pressure

Question 379

T/F: only closure of valves produces sounds in normal healthy adults

Answer 379

True

Question 380

T/F: Because the aorta is such a large vessel, the opening of it during rapid ejection phase creates the "dub" sound in heart

Answer 380

False, only the closing of valves produces sounds in healthy heart

Question 381

Why do BOTH ventricular pressure and aortic pressure increase during rapid ejection (phase 5) of systole?

Answer 381

Because the ventricle is continuing to contract so pressure remains high Aorta now filling with blood

Question 382

The peak pressure measured at phase 5 of systole is termed

Answer 382

Systolic pressure

Question 383

In what phase do we see stroke volume? What is stroke volume?

Answer 383

Stroke volume is the amount of blood expelled by L ventricle into aorta - Seen in phase 5

Question 384

Why does venous pressure drop during rapid ejection phase of systole?

Answer 384

The sudden increase in aorta volume and flow of blood out of ventricle pulls the mitral valve into the ventricle which increases the space in mitral valve which decreases pressure in atria and subsequently the veins

Question 385

What does the ECG tracing show during phase 5 of systole?

Answer 385

Shows ST segment, electrically neutral due to ventricles being completely depolarized

Question 386

What is the name of phase 5 of systole?

Answer 386

Rapid ejection phase

Question 387

What is the name of phase 6 of systole?

Answer 387

Reduced ejection phase

Question 388

In phase 6 of systole: ___________ volume still decreases but at a slower rate ________________ blood flow decreases ______________ and ____________________ pressure begins to decline as less volume is ejected

Answer 388

Ventricular Aortic Aortic & ventricular

Question 389

Why does ventricular pressure begin to drop in phase 6 of systole? Why does aortic pressure begin to drop in phase 6 of systole?

Answer 389

The ventricle contraction begins to taper off so pressure drops The blood in the aorta begins to move out to periphery

Question 390

What is happening to atrial pressure during reduced ejection phase of systole?

Answer 390

The atria is still closed to ventricle and continuing to fill with blood so the pressure rises and thus venous pressure is also rising

Question 391

What tracing is seen on ECG during phase 5 of systole?

Answer 391

The T wave as the ventricles begin to repolarize

Question 392

What marks the end of phase 6, beginning of phase 7 of systole?

Answer 392

Closure of the aorta

Question 393

Why does the aortic valve close?

Answer 393

As the ventricle stops contracting, the pressure begins to drop enough where the aortic pressure is greater than ventricular pressure forcing the aortic valve closed

Question 394

In phase 7 of systole, the drop in pressure of the ventricle and subsequent closure of the aortic valve does what?

Answer 394

The pressure decrease makes the blood want to flow back into the ventricle, but the aortic valve is closed which creates the "Dub" sound, sound 2

Question 395

What does the ECG tracing look like during phase 7, isovolumic relaxation of systole

Answer 395

Isoelectric because all of the cells have repolarized

Question 396

The pressure decrease makes the blood want to flow back into the ventricle, but the aortic valve is closed which creates the "Dub" sound, sound 2. This can also be seen in the pressure of the aorta known as:

Answer 396

Dicrotic notch

Question 397

In phase 7 of systole, both the aortic valve and mitral valve are closed so no volume change in ventricle. But the ventricle never expels all blood volume, the remaining volume is termed:

Answer 397

End systolic volume

Question 398

End Diastolic volume represents the amount of blood in the ventricle when: End Systolic volume represents the amount of blood in the ventricle when: Stoke volume is:

Answer 398

Full After emptying but some blood still remains Difference between these two, about 70 mL as it is the amount of blood pumped out of ventricle

Question 399

Why does atrial pressure rise during phase 7 of systole? Why does venous pressure rise during phase 7 of systole?

Answer 399

The mitral valve is still closed and blood still being received so both venous and atrial pressure up

Question 400

What is cardiac output?

Answer 400

Heart rate * Stroke volume Amount of blood pumped per minute

Question 401

What is normal cardiac output at rest?

Answer 401

5 L/min

Question 402

What is normal stroke volume

Answer 402

70 mL

Question 403

The main neurotransmitter in sympathetic division is:

Answer 403

Norepinephrine which can allow for secretion of epinephrine from the adrenal medulla

Question 404

The sympathetic nervous system is initiated when there is increase in: Works where in the heart: Increases: ________________ and ________________ via action of:

Answer 404

Activity Atria and ventricles Heart rate and contractility Catecholamines

Question 405

What are catecholamines? Give 3 examples

Answer 405

Monoamines that act as hormones and or neurotransmitters 1.) Epinephrine 2.) Norepinephrine 3.) Dopamine

Question 406

The main neurotransmitter in parasympathetic system is: This controls: Works where in the heart: Decreases: ___________ & _______________

Answer 406

Acetylcholine Controls resting heart rate Works mostly Atria via SA & AV node Heart rate and contractility

Question 407

What adrenergic receptors work with norepinephrine?

Answer 407

β adrenergic receptors

Question 408

To increase heart rate via ANS activity: 1.) SNS secretes norepinephrine which acts on β adrenergic receptors 2.) Na+: 3.) Ca+: 4.)

Answer 408

2.) Increase Na+ permeability by accelerating activation of funny current channels in slow type channels (SA/AV node) which increases rate of depolarization 3.) Increased Ca+ permeability 4.) Increases rate and conduction velocity to allow action potential to excite next cells, reactivates faster

Question 409

To control heart rate via PNS: 1.) PNS secretes acetylcholine to Muscarinic receptors 2.) K+: 3.) Na+: 4.) Ca+:

Answer 409

2.) Increase permeability of K+ which increases hyperpolarization to make depolarization harder 3.) Decrease permeability of Na+ to reduce rate of polarization 4.) Decrease Ca+ permeability which delays time it take to reach mV 0 where an action potential could take place

Question 410

Heart rate is majorly controlled by:

Answer 410

SA node and AV node transduction

Question 411

What are the 2 main pathways to control cardiac output?

Answer 411

Intrinsic and extrinsic control

Question 412

What 3 things control stroke volume (vol of blood expelled from ventricle to aorta) ?

Answer 412

Afterload Preload Contractility

Question 413

In Intrinsic control, what increases stroke volume?

Answer 413

Increasing end diastolic volume

Question 414

In intrinsic control, what decreases stroke volume?

Answer 414

Afterload

Question 415

What is preload?

Answer 415

Degree of myocardium stretch before contraction AKA end diastolic volume

Question 416

What is afterload?

Answer 416

Resistance against systolic contraction The pressure generated during ventricle contraction prior to opening aortic valve The pressure that must be overcome to open the aortic valve

Question 417

List 3 other terms for afterload:

Answer 417

1.) Aortic pressure 2.) Arterial pressure 3.) Total peripheral resistance

Question 418

Define contractility

Answer 418

Strength of contraction at any given End diastolic volume

Question 419

What does increasing preload do?

Answer 419

Increases stroke volume buy increasing the volume of blood in the L ventricle

Question 420

What does increasing afterload mean?

Answer 420

Decreases stroke volume: Increasing pressure pushing down on ventricle so the time required for ventricle pressure to supersede aortic pressure to force aortic valve open and expel blood. This means there is less time for the actual contraction and expelling blood because using more time to build up pressure to open aorta

Question 421

Increasing ___________ _____________ >> increases preload >> increases ___________ ________________ >> increases ______________ _______________

Answer 421

Venous return stroke volume cardiac output

Question 422

As venous pressure rises, cardiac output drops, why?

Answer 422

Because there is more pressure that venous return must push against the the volume returning to heart is less which reduces amount of blood that can be returned to heart and subsequently expelled

Question 423

Define: Frank-starling law

Answer 423

Energy of contraction is proportional to the initial length of the cardiac muscle fiber

Question 424

Since cardiac myofibers cannot recruit more cells to increase tension, what law and concept is used to increase contraction

Answer 424

By increasing filling of heart, the stretch and tension of myofilaments is increased to reach optimal sarcomere overlap which allows for stronger recoil

Question 425

What mechanism works in exerting extrinsic control on stroke volume

Answer 425

Sympathetic nervous activity

Question 426

Increasing _____________________ via activation of sympathetic nervous system will increase ______________________ via extrinsic control to overall, increase ________________ ________________

Answer 426

contractility stroke volume cardiac output

Question 427

Define: contractility

Answer 427

Strength of contraction at any given end diastolic volume

Question 428

Positive ionotropic effect is equivalent to: It is enabled by catecholamines or digoxin

Answer 428

increasing contractility and thus inc. stroke vol, subsequently inc. cardiac output

Question 429

Negative ionotropic effect is equivalent to: It is enabled by β blockers or heart failure

Answer 429

Decreasing contractility, thus decreasing stroke volume and subsequently decreasing cardiac output

Question 430

β blockers will decrease ionotropic and chronotropic activity of heart, meaning:

Answer 430

Decreased contractility Decreased HR Decreased Cardiac output overall

Question 431

How does the sympathetic nervous system increase contractility of the heart?

Answer 431

SNS secretes norepinephrine which acts on β₁ receptors which 1.) increases permeability of Ca+, easier to activate L type channels 2.) increases quantity of L type calcium channels in ventricle tissue 3.) Increase Phospholamban activity to increase Ca+ sequestering to increase EDV Allows for more forceful contraction

Question 432

List the 3 physiologic areas of importance in fetal circulation

Answer 432

Ductus arteriosus, foramen ovale, ductus venosus

Question 433

In fetal circulation the L and R heart pump: Why is this?

Answer 433

In Parallel Because only some blood goes into pulmonary artery unlike in adults

Question 434

In fetus, where is the ductus arteriosus located?

Answer 434

Between the pulmonary artery and shunts blood straight to the aorta to systemic circulation

Question 435

In fetus, where does O² come from?

Answer 435

Comes from the placenta, the O² diffuses across the placenta and is delivered via the ductus venosus

Question 436

In utero, oxygenated blood comes up through the inferior vena cava via:

Answer 436

Ductus venosus that connects to the placenta

Question 437

In fetus, blood from the R atrium shunts directly to the L atrium via:

Answer 437

Foramen ovale

Question 438

In fetus, though both sides pump in parallel, which side of the heart pumps more volume? Why is this so?

Answer 438

R heart heart Since not much blood is being pumped into the pulmonary artery, not much vol blood being returned to L side of heart

Question 439

T/F: In fetus, cardiac output is irrelevant and more focus on combined ventricular output due to the L side of heart pumping more volume than the R

Answer 439

False, R side pumps more volume than L

Question 440

About how much fetal blood passes through the ductus arteriosus? Where is the ductus arteriosis?

Answer 440

~60% of blood volume Shunts blood coming from R ventricle to pulmonary artery straight to aorta

Question 441

Why is the volume of blood in fetus large?

Answer 441

Because the O² concentration in fetal blood is low, so need more volume to have enough O²

Question 442

What is the [ O² ] in aorta of fetus?

Answer 442

65%

Question 443

What is the [ O² ] in RV and LV of fetus?

Answer 443

RV: 55% LV: 65%

Question 444

Where does Oxygenated blood come from when considering blood going to brain and coronary circulation in fetal circulation? Why?

Answer 444

From the aorta since it has the highest O2 saturation

Question 445

During late stages of gestation, the lungs and gut receive larger % combined ventricular output to engage maturity for birth. Compare or contrast this to fetal regional blood flow of brain, lungs, kidney, gut.

Answer 445

While the lung and gut start to get a larger percentage of ventricular output, the kidney remains with the highest regional blood flow. The brain and lungs also have greater absolute flow compared to the gut further in gestation.

Question 446

T/F: Since the L and R heart pump in parallel in fetal circulation, the oxygen circulating in fetal circulatory is even

Answer 446

False, the most oxygenated blood is biased towards the brain and coronary circulation

Question 447

Describe the first breath after birth

Answer 447

Difficult because the lungs are stiff Need a very large negative pressure to forcefully expand lungs ▪️ - pressure as low as 60 mmHg and + pressure as high as 40 mmHg to expand the lungs

Question 448

What mechanism aids in second breath after birth to make breather easier?

Answer 448

Production of pulmonary surfactant to decrease surface tension in alveoli Fluid in lungs is reabsorbed so the inflation of lungs is easier

Question 449

About how long after birth is pressure volume loop comparable to adults?

Answer 449

~ 40 min, effective change in volume with small changes in +/- pressure

Question 450

During gestation, pulmonary vascular resistance is high so blood flow is low, does this change after birth?

Answer 450

Yes, because the ductus arteriosus closes and no longer straight shunt from R ventricle to pulmonary artery to aorta So the blood may go through low resistance pulmonary circulation and arterial pressure drops while blood flow increases

Question 451

What may happen in the pulmonary vascular resistance does not decrease after birth?

Answer 451

Persistent pulmonary hypertension of newborn

Question 452

Approximately where is fetal blood pressure maintained?

Answer 452

40-50 mmHg

Question 453

T/F: Since O2 and CO2 diffuse between air in lungs and pulmonary circulation they freely travel through systemic ciruclation

Answer 453

False, O2 and CO2 are not very soluble in the blood and must use other transport mechanisms

Question 454

When breathing in, the ____________________ expands and the ___________________ lowers to pull lungs toward pleural space and expand. This makes the pressure in the pleural space more ____________________ which causes lungs to expand.

Answer 454

Chest wall diaphragm negative

Question 455

What condition of the pleural space helps hold lungs open?

Answer 455

The slightly negative pressure in pleural space

Question 456

Each alveolus is surrounded by:

Answer 456

Pulmonary capillaries

Question 457

T/F: In addition to pulmonary circulation, the lungs also have bronchial circulation

Answer 457

True

Question 458

What is the purpose of the bronchial circulation?

Answer 458

To supply blood to areas of lung that do not undergo gas exchange

Question 459

The blood coming from the pulmonary vein is not 100% O2 saturated, why?

Answer 459

Because of the bronchial circulation. This circulation system supplies oxygen to the lungs that do not undergo gas exchange so when this blood leaves the lungs it is not fully oxygenated and is returned to pulmonary venous which lowers the O2 saturation AKA right to left shunt

Question 460

What does high compliance mean?

Answer 460

Can have large change in volume for low change in pressure

Question 461

T/F: Since pulmonary arteries and branches are under involuntary control, they are surrounded by smooth muscle

Answer 461

False

Question 462

Why is it so important for pulmonary circulation to exhibit high compliance?

Answer 462

1.) When cardiac output increases, the volume can greatly increase and low pressure must be maintained during this increase

Question 463

T/F: The diameter and length of pulmonary vessels can be changed easily by mechanical forces like in the rest of the body

Answer 463

False, only applicable to pulmonary circulation

Question 464

ΔPressure = ______________________ X _______________________

Answer 464

ΔPressure = Flow X resistance

Question 465

Cardiac output must be <,>, = in systemic and pulmonary circulation

Answer 465

Must be equal since they are in series with each other

Question 466

______________ and _______________ factors can change pulmonary resistance

Answer 466

Passive and active

Question 467

List 3

Question 468

What is transmural pressure?

Answer 468

Pressure gradient across the wall of a vessel, trachea ' P in- P out

Question 469

Where are extra alveolar vessels located?

Answer 469

In the pleural space and not surrounded by alveoli NOT part of bronchial circulation

Question 470

Pulmonary circulation is a _____________ pressure, _________ resistance, and ___________ compliance circulation.

Answer 470

low low high

Question 471

At large lung volumes (inspiration), the resistance in extra-alveolar is ___________ while the alveolar vessel ___________________. Why?

Answer 471

decreases increases Since the chest wall is expanding, the pleural space becomes more negative which allows more room for extra alveolar vessel The alveoli are expanding which lengthens and squishes the alveolar vessels

Question 472

At what point is lowest total resistance in the lungs? At what point is there highest total resistance in the lungs?

Answer 472

Functional residual capacity Residual volume (where the minimum amount of air is present and the rest is forcefully expelled)

Question 473

During expiration, resistance increases: resistance decreases: Why

Answer 473

Resistance increases in extra alveolar space b/c the intrapleural pressure is increasing Resistance decreases in alveolar space b/c pressure decreasing and vessels are shortening

Question 474

How do you calculate total vascular resistance of the lung:

Answer 474

Add alveolar and extra alveolar resistance since they are in series the resistance is additive

Question 475

List the 3 components of passive control of pulmonary vascular resistance

Answer 475

1.) Lung volume and the transmural pressure gradient across the vessels 2.) Pulmonary blood flow & blood pressure 3.) Gravity

Question 476

In lungs, as pulmonary arterial pressure increases, resistance ____________________. Why?

Answer 476

Decreases due to high compliance of pulmonary

Question 477

Describe recruitment in terms of passive control of pulmonary vascular resistance

Answer 477

In the lungs, all vessels are open but not all have flowing blood because pressure is not high enough to force blood through them As pressure rises, these vessels begin to fill with blood Happens in the apex of the lung

Question 478

Following recruitment of vessels in the lung ,there is distention for passive pulmonary resistance control. What is the distension?

Answer 478

After the capillaries are all recruited, these vessels can easily stretch to increase amount of blood flowing through them

Question 479

Where in the lung is there the greatest blood flow? Why is it not uniform?

Answer 479

In the base Due to gravity. Since the pulmonary artery is below the apex of the lung, most of blood flows toward the base

Question 480

Where is vascular pressure highest in the lung?

Answer 480

At the base again because blood flow is the greatest here

Question 481

When is alveolar pressure = to atm?

Answer 481

Between breaths when the trachea is open

Question 482

Explain the pressure difference between arterial pressure, alveolar pressure and venous pressure in Zone 1 (Apex) of the lung. How does this affect pulmonary vessels

Answer 482

Alveolar pressure is greatest Arterial pressure is greater than venous pressure Pulmonary vessels are squished with no blood flow

Question 483

Explain the pressure difference between arterial pressure, alveolar pressure and venous pressure in Zone 2 of the lung. How does this affect pulmonary vessels

Answer 483

Arterial pressure is largest Alveolar pressure is larger than venous pressure Some blood flow through vessels but limited due to alveolar pressure being higher than venous pressure, so resistance is high enough to reduce blood flow

Question 484

Explain the pressure difference between arterial pressure, alveolar pressure and venous pressure in Zone 3 (base) of the lung. How does this affect pulmonary vessels

Answer 484

Arterial pressure greatest Alveolar pressure larger than venous pressure Arterial pressure high enough to push blood flow entirely through the vessel

Question 485

What are 2 conditions where in Zone 1 would exist in the lung. FYI zone 1 does not normally exist under normal circumstances

Answer 485

1.) Positive pressure ventilation 2.) During hemorrhage

Question 486

What is the most important factor mediating active control of pulmonary circulation is:

Answer 486

Oxygen

Question 487

_____ Partial pressure of oxygen in the alveolar air causes: This is termed hypoxic pulmonary vasoconstriction

Answer 487

Low vasoconstriction of small pulmonary arteries

Question 488

When would hypoxic pulmonary vasoconstriction exhibit preserving effects?

Answer 488

I.e. if something is obstructing part of the lung, the blood flow will be directed AWAY from that area since it cannot participate in gas exchange

Question 489

At high altitude what happens to partial pressure of oxygen? How does this affect physiology?

Answer 489

The partial pressure of oxygen is lowered so vasoconstriction occur which increases pulmonary arterial pressure

Question 490

High partial pressure of ______ and low pH in the alveolus can promote vasoconstriction

Answer 490

CO2 Importantly, this acts on SMALL level compared to active control based in O2 partial pressure

Question 491

Describe normal pulmonary capillary fluid balance.

Answer 491

Since the overall arterial pressure is low, the hydrostatic pressure is low and little fluid is exchanged in pulmonary capillaries. What little amount is pushed out is removed via lymphatic system

Question 492

How might heightened arterial pressure effect pulmonary capillary fluid balance?

Answer 492

If the arterial pressure increases the hydrostatic pressure in capillaries then too much fluid may be pushed into interstitial space that the lymphatic system is not able to remove Pulmonary edema

Question 493

Describe the early stage (interstitial edema)

Answer 493

fluid between capillary and alveolus increases diffusion distance between oxygen and carbon dioxide between alveoli and plasma reducing gas exchange in the lung

Question 494

What is happening in late stage edema?

Answer 494

The alveoli are filled with fluid so gas exchange cannot take place

Question 495

The _____________ contributes a large amount of Angiotensin I conversion. Why?

Answer 495

Angiotensin I converted to Angiotensin II via ACE Because the lung receives such a high volume of blood, the entire circulation

Question 496

Hemodynamics: Pressure difference drives _________________. Amount of flow is determine by:

Answer 496

Flow ΔP and resistance

Question 497

What is the equation to calculate Ohm's law

Answer 497

ΔP = Flow * resistance Flow may also be represented as Q or Q.

Question 498

Hemodynamics: Resistance = k/ radius ^ _____

Answer 498

power of four So if P same, as radius INCREASES, resistance decreases As radius DECREASES, resistance INCREASES

Question 499

Hemodynamics: How do resistance and length relate to each other.

Answer 499

They are proportional where, Resistance = k * Length If Length increases so does resistance

Question 500

Why is it important for terminal arterioles to be the primary resistance vessels of the body?

Answer 500

Because by increasing the resistance at terminal arterioles, and decreasing radius, the flow slows down to allow time for gas and nutrient exchange at the capillary beds

Question 501

What is the equation representing the la of LaPlace?

Answer 501

Wall tension (T) = P (hydrostatic pressure) * R (radius) Wall tension=force pulling vessel apart

Question 502

In the law of LaPlace, the increase in radius increase wall tension, why is this?

Answer 502

B/c if the radius is bigger, there is more surface area for the hydrostatic pressure to interact with thus increasing the wall tension

Question 503

If terminal arteriole resistance is high, why is total peripheral resistance not correspondingly high?

Answer 503

Because the parallel arrangement of the vasculature reduces the overall resistance

Question 504

The mean arterial pressure is:

Answer 504

Average pressure OVER TIME (between systolic and diastolic)

Question 505

How to calculate Mean Arterial pressure:

Answer 505

MAP = 1/3 (systolic pressure) + 2/3 (diastolic pressure)

Question 506

T/F: Velocity is the same as blood flow

Answer 506

False, flow is a component comprising velocity

Question 507

If wanting to relate flow and velocity of blood, what must be accounted for? How are all 3 components related?

Answer 507

Velocity = Flow/total area (cross sectional area)

Question 508

Where does Ca+ bind in skeletal muscle during excitation contraction?

Answer 508

Binds to troponin C

Question 509

What happens after Ca+ binds to troponin C?

Answer 509

The troponin moves the associated tropomyosin towards the cleft which allows exposure of the myosin binding site of the actin filament

Question 510

In the resting state, what is connected to the myosin heads?

Answer 510

ADP and Phosphate

Question 511

When Pi is released from myosin, what happens?

Answer 511

The power stroke, the myosin heads rotate down which moves the actin filament on top of itself After ADP is released

Question 512

What is attached to myosin and thin filament during rigor state?

Answer 512

Nothing, the ADP and Pi have been released

Question 513

What is ATP role in cross-bridge cycling

Answer 513

ATP promotes the release of myosin heads from thin filaments but still bent Myosin will convert the ATP to ADP and Pi to return to upright orientation They hydrolysis of ATP to ADP and P on thick filament sets up for power stroke

Question 514

How is cross bridge cycling ceased?

Answer 514

Ca+ is "sequestered" aka pulling Ca back into the sarcolemma via SERCA

Question 515

What is SERCA?

Answer 515

Calcium ATPase that pulls Ca from the sarcomere back into the sarcolemma

Question 516

What is the most abundant protein in the sarcoplasmic reticulum of skeletal muscle?

Answer 516

SERCA

Question 517

SERA transports ____ molecules of Ca+ for each _______ hydrolyzed

Answer 517

2 molecules Ca+ re-sequestered for every ATP hydrolyzed

Question 518

Where is calcium stored in skeletal muscle?

Answer 518

Calsequestrin stores the calcium in SR so Ca is ready to flow through RyR

Question 519

How does arterial compliance impact circulation?

Answer 519

Arteries are relatively non-compliant. There is some stretch, so during systole the small stretch build ability for elastic recoil that is engaged during diastole to further expel blood

Question 520

How does blood flowing through vessel walls seemingly decrease viscosity?

Answer 520

The RBC flowing through the vessel interact with the wall which optimizes flow

Question 521

What is "shear thinning" and how does it impact blood viscosity?

Answer 521

The tendency for erythrocytes to move to center of the tube where higher flow rate occurs Higher velocity causes shear thinning Aggregation decreases in this state and such blood viscosity decreased

Question 522

T/F: As vessel diameter decreases, viscosity decreases. If so, why?

Answer 522

T As blood vessels become smaller with the same volume flowing through increases velocity

Question 523

List the 5 components that affect blood visocity

Answer 523

Hct Plasma proteins Shape of RBC Velocity of flow Vessel Diameter

Question 524

What is Renyolds number used for?

Answer 524

Used to predict if blood flow will be turbulent of laminar

Question 525

Which type of flow is preferred, turbulent or laminar? Why?

Answer 525

Laminar Organization of flow is in parallel Blood flow toward the center is fastest while the blood flow on the wall is slowest Most efficient

Question 526

Why can turbulent flow be heard?

Answer 526

Because the turbulent flow is not energy efficient, and energy lost is converted to sound

Question 527

Central venous pressure is synonymous to:

Answer 527

Right atrial pressure

Question 528

When cardiac output is normal (5 L/min) the central venous pressure is low, why?

Answer 528

The cardiac output is pulling blood out of the veins, lower volume decreases pressure, which allows for more volume to enter the veins

Question 529

How does increasing volume increase central venous pressure and vice versa?

Answer 529

Increasing the overall volume increases Cardiac output, if overall cardiac output increases the central venous pressure increases OVERALL

Question 530

Why does vasodilation (decreased resistance) increase cardiac output when volume and central venous pressure are the same?

Answer 530

The resistance is lowered so the blood returns to heart faster. For each central venous pressure increases cardiac output due to increased flow back to heart

Question 531

Why does vasoconstriction (increase resistance) of central venous pressure decrease cardiac output

Answer 531

The resistance reduces blood flow back to the heart so for each venous pressure, the flow returning to heart is less and cardiac output is lowered

Question 532

How does gravity negatively affect cardiac output?

Answer 532

Gravity causes blood to pool in veins and venous pressure to increase in legs and ankles

Question 533

What are 4 components that drive venous return?

Answer 533

1.) Valves 2.) Skeletal muscle contraction 3.) Respiration 4.) Heart beat

Question 534

Describe the thoracic pump and how contributes to venous return

Answer 534

When inspiring, the pressure surrounding the lungs is decreased which pulls blood back toward the heart

Question 535

Describe how heart beats contribute to venous return

Answer 535

Each heartbeat pulls blood into the atria during systole due to high pressure in ventricles

Question 536

Maintenance of blood pressure at a minimum value is monitored: Maintenance of blood pressure at a maximum value is monitored:

Answer 536

Moment to moment Over time

Question 537

What is the most important neural reflex mechanism controlling blood pressure on a minute to minute basis?

Answer 537

Arterial baroreceptor reflex

Question 538

What do Atrial receptor reflexes do?

Answer 538

Considered low pressure receptors, sense volume Regulate effective circulating blood volume and cardiac output Indirect control In place during dehydration and blood loss

Question 539

What are the 2 reflexes that maintain cerebral blood flow?

Answer 539

Cerebral ischemia reflex Cushing reflex

Question 540

The arterial baroreceptor reflex provides ______________ feedback

Answer 540

Negative, so more stretching increases afferent activity to tell the brain decreases effector action

Question 541

Where are baroreceptors found?

Answer 541

Aortic arch and carotid sinus

Question 542

When arterial baroreflexes are stretch and afferent neurons are stimulated, when the response from brain goes to efferent neurons, the sympathetic and parasympathetic system are activated. Where is the Sympathetic system signaled? Where is the Parasympathetic system signaled?

Answer 542

From the nucleus of solitary tract: Nucleus ambiguous corresponds to Parasympathetic Caudal ventral lateral medulla to regulate sympathetic activity

Question 543

The carotid sinus and aortic arch have baroreceptors and chemoreceptors called:

Answer 543

Carotid bodies and aortic bodies

Question 544

Arterial chemoreceptors are activated by changes in: 1.) Decreased partial pressure ______ 2.) Increased partial pressure ____ 3.) _______ pH Their stimulation causes an _______________ in blood pressure

Answer 544

O2 CO2 low Increase

Question 545

Increasing the activity of the Nucleus ambiguous will increase _________________________. Which will: 1.) 2.) 3.)

Answer 545

Parasympathetic nervous system 1.) increase vessel diameter 2.) Decrease contractility 3.) Decrease HR

Question 546

Increase in BP: 1.) 2.) Increase afferent signaling to nucleus of the solitary tract 3.) 4.) Decrease rostral ventrolateral medulla 5.) Decrease sympathetic activity

Answer 546

1.) Stretches baroreceptors 2.) 3.) Increase activity to caudal ventral lateral medulla 4.) 5.)

Question 547

Why does chemoreceptor activation increase contractility, decrease vessel diameter with varied effects on heart rate?

Answer 547

Because activation of the chemoreceptors activates NTS which activates the Nucleus ambiguous so increase parasympathetic nervous system AT THE SAME TIME The RVLM is also increased directly so sympathetic activation is also increased

Question 548

The sympathetic nervous system innverates: 1.) 2.) 3.) 4.) 5)

Answer 548

Heart Kidneys vessels adrenal medulla arterioles

Question 549

T/F: The parasympathetic system innervates vessels to constrict vessel diameter

Answer 549

False Parasympathetic does not innervate vessels

Question 550

Parasympathetic efferent neurons synapse:

Answer 550

Vagus nerve to induce heart changes

Question 551

Ach is release by POST ganglions of _________________________ to act on _______________________ receptors Norepinephrine is released by POST ganglions of _____________________________________ in ___________________.

Answer 551

parasympathetic nervous system to act on muscarinic receptors sympathetic nervous system to action on α & β adrenergic receptors

Question 552

Sympathetic preganglion that synapse in the adrenal medulla:

Answer 552

Induce release of norepinephrine and epinephrine to diffuse into blood stream for α & β adrenergic receptors

Question 553

Increased contractility:

Answer 553

Increases cardiac output

Question 554

The B 1 receptors increase: 1.) 2.)

Answer 554

Increase HR Increase contractility (inc. cardiac output)

Question 555

T/F: The parasympathetic nervous system acts in exact opposite in reduce arterial pressure by reducing heart rate and contractility.

Answer 555

False, the parasympathetic NS only can decrease heart rate at the SA node

Question 556

In humans, the ___________________________ nervous system control of heart rate predominates at rest

Answer 556

Parasympathetic

Question 557

How does the sympathetic nervous system exert vascular effects? How about parasympathetic effects on vasculature?

Answer 557

SNS: Alpha receptors are respondent to epinephrine and norepinephrine which to vasoconstrict with increases resistance PSNS: None

Question 558

The Sympathetic nervous system innervates constriction to both arteries and veins. How does this raise BP?

Answer 558

Inc resistance of arteries, Inc Pressure Increase venous tone, increases venous return to raise cardiac output

Question 559

When sympathetic NS releases norepinephrine to act on _______ receptors in the kidney, there is stimulation of ____________ secretion

Answer 559

β1 adrenergic receptors Renin secretion

Question 560

What does renin do?

Answer 560

Inc. Angiotensin II

Question 561

Increased Angiotensin II: 1.) 2.) 3.)

Answer 561

1.) Inc plasma sodium which inc blood pressure 2.) Inc aldosterone, which inc. plasma sodium 3.) Vasoconstrictor to increase total peripheral resistance 4.) stimulate neurons that project into brain to increase SNS

Question 562

What does Aldosterone do?

Answer 562

Increases plasma sodium which can increase blood pressure

Question 563

T/F: Angiotensin II can act in the brain to increase Sympathetic nerve activity

Answer 563

Partly true, it cannot cross the blood brain barrier but Angiotensin II can be made in the brain to inc. SNS

Question 564

When arterial baroreflex sense drop in blood pressure, they can cause downstream effect of increase vasopressin. How does vasopressin increase blood pressure

Answer 564

1.) The vasopressin increases water reabsorption in the collecting duct 2.) Also acts as a vasoconstrictor

Question 565

Tonic _______ activity exerts tonic vasoconstrictor activity The balance of tonic _______ and tonic ________ determines HR

Answer 565

SNS PNS & SNS

Question 566

During total spinal anesthesia, the _______________ neurons action are removed which:

Answer 566

Efferent neurons No tonic input and BP falls

Question 567

If PNS and SNS tonic activity is removed, can you increase arterial pressure?

Answer 567

Yes, by injecting norepinephrine to simulate Alpha and Beta adrenergic receptors

Question 568

How does hypertension occur if baroreceptors regulate blood pressure?

Answer 568

If there is prolonged arterial pressure increase, the baroreceptors will become tolerant to the high blood BUT minute to minute regulation will still be in place

Question 569

In dogs, if baroreceptor responses are removed, what happens to pressure and mean arterial pressure?

Answer 569

The blood pressure has wide range but the mean arterial pressure stays the same due to CNS regulation

Question 570

Where are stretch receptors, AKA atrial receptors found? What do they do?

Answer 570

Found in R atria, Type B firing Detect Volume changes

Question 571

__________________ ________________ respond when end diastolic volume is too low or too high. They also fire when cellular ischemia is present. They exert effects via parasympathetic activity

Answer 571

Ventricular receptors

Question 572

What is the cushing response?

Answer 572

Increase SNS and endocrine response to increase blood pressure when there is elevated CSP pressure that has reduces blood flow by construction of blood vessels surrounding

Question 573

Why does heart rate decline with advanced age?

Answer 573

The β adrenergic mediation of increasing heart rate and signaling declines

Question 574

Describe how stroke volume is changed with advanced age

Answer 574

Preload is reduced: stiffening=reduced filling Afterload is reduced: reduction of ejection fraction due to increased BP and widened pulse pressure

Question 575

What is ejection fraction?

Answer 575

Amount ejected from ventricle/mL contained in ventricle

Question 576

What contributes of afterload?

Answer 576

- Vascular pressure (ventricular pressure must be higher than systemic to open aorta)