1.4 The heart as a pump 43-58

Question 1

Cardiac muscle tissue is composed of what kind of muscle cells:

Answer 1

Striated

Question 2

How are striated heart muscles cells anchored at their ends?

Answer 2

Intercalated discs

Question 3

Why is the syncytium of cardiac muscle important?

Answer 3

Allows rapid coordinated contraction/action potential from cell to cell (slowly)

Question 4

The heart is a demanding tissue that requires:

Answer 4

Extensive capillary density within endomysium to deliver steady supply of O2

Question 5

Ischemia

Answer 5

Reduction in O2

Question 6

With would happen without syncytium?

Answer 6

Cell won’t maintain polarized state, will reach action potential and fire out of sequence

Question 7

A non-regenerating tissue with cells that are capable of hypertrophy (add new myofibrils) when worked hard

Answer 7

Cardiac muscle

Question 8

Responsive to chronic stresses

Answer 8

Cardiac muscle Ie. Pressure and/or volume loading

Question 9

Cells that abandoned much of their myofibrillar apparatus for rapid impulse conduction/propagation:

Answer 9

Purkinje cells

Question 10

What is Purkinje’s system?

Answer 10

Network of Purkinje fibers that carry cardiac impulse from AV node to ventricles of the heart and causes them to contract. Acts as a wiring to get depolarization stimulus everywhere at the right time (as opposed to the normally slower paced propagation between cells due to intercalated disks.)

Question 11

The action potential of cardiac, contrite cells is very _____ and has 3 basic phases:

Answer 11

Long

1. Depolarization
2. Plateau
3. Repolarization

Question 12

Rapid influx of Na+ as voltage gates then open Ca2+ channels

Answer 12

Depolarization

Question 13

Contraction happens at this phase:

Answer 13

Plateau AKA absolute refractory period (ARP)

Question 14

The phase when the cell is resistant to stimulation, cytosolic Ca2+ rises and induces SER release of Ca2+ reserves

Answer 14

Plateau / absolute refractory period

Question 15

This phase consists of a variable sensitivity period known as relative refractory period

Answer 15

Repolarization

Question 16

When K+ is relocated to the interior, as at rest

Answer 16

Repolarization

Question 17

The end of the relative refractory period (RRP) has a period of

Answer 17

Supranormal excitability period (SNP)

Question 18

Where stimulation easily causes another depolarization and contraction

Answer 18

Supranormal excitability period (SNP)

Question 19

As a cell is _____ during relaxation, it tends to produce a stronger contraction in the next cycle

Answer 19

Lengthened

Question 20

Action potentials are ____ depending upon the particular cardiac muscle cell examined (form, duration, timing)

Answer 20

Variable

Question 21

Nodal tissue tends to be ___ to depolarize but ___ to repolarize.

Answer 21

Slow; quick

Question 22

Spontaneous action potentials are called

Answer 22

Auto-rhythmicity

Question 23

In auto-rhythmicity, membranes are:

Answer 23

Leaky to inward movement of ions

Question 24

Are nerves needed in auto-rhythmicity?

Answer 24

No. Though may modulate action

Question 25

Cardiac muscle cells are complexly covered with

Answer 25

Receptors

Question 26

What renders cardiac cells sensitive to some hormones and neurotransmitters from the autonomic nervous system?

Answer 26

Receptors

Question 27

What two broad category receptors are on the cardiac muscle?

Answer 27

Adrenergic receptors Cholinergic receptors

Question 28

Receptors that bind adrenergic agonists such as sympathetic neurotransmitter norepinephrine and circulating hormone epinephrine

Answer 28

Adrenergic

Question 29

What Adrenergic receptor is sensitive to norepinephrine and released from the axons of sympathetic fibers?

Answer 29

β1 receptors

Question 30

What receptor increases excitability, strength and rate of contraction by hypo-polarizing the plasma membrane of the cell through G-protein signaling?

Answer 30

Adrenergic receptors (primarily β1 receptors)

Question 31

Adrenergic receptors bind to

Answer 31

Norepinephrine and epinephrine

Question 32

What receptor works by decreasing excitability, strength and rate fo contraction by tending to hyperpolarize the membranes (through G-protein signalin)

Answer 32

Cholinergic receptors

Question 33

How does cholinergic receptors work

Answer 33

Ach “muscarinic” receptors sensitive to acetylcholine released from axons of parasympathetic fibers

Question 34

Describe the flow of blood through the heart starting with the IVC/SVC

Answer 34

Right atrium —\> Right ventricle —\> Pulmonary trunk, arteries —\> lungs —\> pulmonary veins —\> Left atrium —\> left ventricle —\> ascending aorta, etc.

Question 35

Name the valves that prevent retrograde (backwards) flow of the blood

Answer 35

Atrioventricular (AV) valves Tricuspid and Bicuspid/Mitral valves Semilunar valves: aortic and pulmonic

Question 36

Both the left and right ventricles must pump the ____ amount of blood per unit time.

Answer 36

Same

Question 37

The systemic circulation is ______ while the pulmonary circulation is \_\_\_\_\_\_

Answer 37

Large; small

Question 38

Contraction and ejection of blood

Answer 38

Systole

Question 39

Relaxation and filing of blood

Answer 39

Diastole

Question 40

The full action of the heart per beat is usually presented as a classic, integrated, display of all relevant activity of the heart and is known as

Answer 40

Cardiac cycle

Question 41

In the cardiac cycle, atrial pressure supplies

Answer 41

additional filling to the ventricles (not important for us)

Question 42

In the cardiac cycle, the heart sounds are called

Answer 42

phonocardiogram, clinically important

Question 43

In the cardiac cycle, the thing that gets it all going

Answer 43

electrocardiogram (ECG)

Question 44

In the cardiac cycle, the "bottom line" product of contraction

Answer 44

ventricular volume

Question 45

In the cardiac cycle, the arterial blood pressure (left side output)

Answer 45

aortic pressure

Question 46

In the cardiac cycle, the source of most initial ∆P

Answer 46

ventricular pressure

Question 47

Memorize Wiggers diagram (sketch it out)

Answer 47

check your work

Question 48

25% of ventricular filling is done by \_\_\_\_\_. The other 75% is done by:

Answer 48

atrial systole (at rest) blood pouring straight from great veins through atria into ventricles.

Question 49

Ventricular diastole subphases:

Answer 49

1. isovolumetric relaxation 2. rapid inflow (75% passive filling) 3. diastasis 4. atrial systole (25% active filling)

Question 50

Ventricular systole subphases:

Answer 50

1. isovolumetric contraction 2. ejection

Question 51

end-diastolic volume (EDV) = the volume at end of diastole

Answer 51

~130 ml

Question 52

end-systolic volume (ESV) = volume end of systole

Answer 52

~60 ml

Question 53

stroke volume (SV) equation

Answer 53

SV = EDV - ESV

Question 54

average stroke volume

Answer 54

~70 ml

Question 55

a useful indicator of heart performance

Answer 55

ejection fraction

Question 56

ejection fraction equation

Answer 56

SV/EDV

Question 57

an event occurring in early systole during which the ventricles contract with no corresponding volume change

Answer 57

period of isovolumetric contraction (AKA isovolumic or isometric)

Question 58

once ventricular pressure exceeds aortic pressure, then aortic valve opens and the ____ begins

Answer 58

period of ejection

Question 59

systolic pressure (systolic BP) should be

Answer 59

~120 mm Hg

Question 60

diastolic pressure (diastolic BP) should be

Answer 60

~80 mm Hg

Question 61

a secondary upstroke in the descending part of a pulse tracing corresponding to the transient increase in aortic pressure upon closure of the aortic valve

Answer 61

dicrotic notch

Question 62

2 principle heart sounds, S1 is described as the:

Answer 62

LUB

Question 63

2 principle heart sounds, S2 is described as the:

Answer 63

DUB

Question 64

S1 is the closure of __________ while S2 is the closure of \_\_\_\_\_\_\_\_\_\_\_

Answer 64

AV valves; semilunar valves

Question 65

What is the valvular abnormality due to difficulty pushing blood through aortic valve. Loud and strong murmur during LEFT ventricular ejection heard throughout systole that is sometimes be felt as a "thrill."

Answer 65

aortic stenosis

Question 66

What is the valvular abnormality that is regurgitation, when the valve fails to prevent backflow into the left ventricle. Often heard as a "blowing" murmur or higher pitch swishing sound through diastole.

Answer 66

aortic insufficiency

Question 67

What is the valvular abnormality that is due to difficulty pushing blood through mitral valve? Creates a weak/low-pitched murmur sound heard in the 2nd half of diastole but especially the later aspect (atrial systole)

Answer 67

mitral stenosis

Question 68

What is the valvular abnormality that is regurgitation, occurring when the valve allows blood back into the left atrium? Creates a blowing, swishing murmur heard throughout systole.

Answer 68

mitral insufficiency

Question 69

All valvular abnormalities due to stenosis or insufficiency usually _________ the net stroke volume

Answer 69

reduce

Question 70

extra strain due to stenosis, the cardiac muscle will usually

Answer 70

hypertrophy

Question 71

serious overload on the heart leads to chamber \_\_\_

Answer 71

dilation

Question 72

cardiac output for resting adult is about

Answer 72

5000 ml/min

Question 73

name the 2 basic mechanisms to regulate cardiac output

Answer 73

intrinsic autoregulation (self-regulated) reflex / extrinsic control (nervous)

Question 74

The law states that the stroke volume of the heart increases in response to an increase in the volume of blood in the ventricles, before contraction (the end diastolic volume), when all other factors remain constant

Answer 74

law of the heart AKA frank-starlin mechanism

Question 75

law of the heart is sometimes stated simply as _____ in venous return leads to _____ in cardiac output

Answer 75

an increase; an increase

Question 76

peripheral factors, which affect returning blood flow, are more important than

Answer 76

cardiac factors

Question 77

blood pressure does/does not normally affect cardiac output

Answer 77

does not

Question 78

sympathetic innervation include numerous nerves from

Answer 78

spinal sympathetic chain

Question 79

parasympathetic innervation includes

Answer 79

2 vagus cranial nerves

Question 80

conduction speed

Answer 80

dromotropic effect

Question 81

rate of contraction

Answer 81

chronotropic effect

Question 82

strength of contraction

Answer 82

inotropic effect

Question 83

What serves as landing site for neurotransmitter norepinephrine from sympathetic innervation on the heart? (also epinephrine from adrenal glands)

Answer 83

β1 adrenergic receptors

Question 84

How do β1 adrenergic receptors affect dromotopism, chronotropism and inotropism?

Answer 84

positive (by opening Na+ and Ca2+ channels)

Question 85

a heart rate greater than or equal to 100 bpm is perfectly normal in many situations but not at rest

Answer 85

tachycardia

Question 86

some cardiac myocytes respond to this parasympathetic neurotransmitter ____ because it displays receptors for it

Answer 86

acetylcholine

Question 87

how does acetylcholine affect dromotropism (conduction speed), chronotropism (rate of contraction), inotropism (strength of contraction)?

Answer 87

makes them negative

Question 88

a heart rate less than or equal to 60 bpm is sometimes perfectly normal, sometimes abnormal

Answer 88

bradycardia

Question 89

reflex control is

Answer 89

rapid and anticipatory