lecture 4: guyton chapter 14

Question 1

where is conduction in the heart initiated

Answer 1

SA node

Question 2

when there is conduction at the SA node explain the depolar

Answer 2

1) signal initiated at the SA node (1 cell depolarizes and reaches the rest through synsitium
2) Sign travels to AV node and is slowed down (to allow atrial contraction first)
3) Signal passes through the bundle of His (allows the signal to pass through atria to ventricles
4) Purkinje fibers

Question 3

Why and how is conduction slowed down at AV node

Answer 3

it has less gap junctions
slowed to allow atria to contract befroe ventricles (max blood filling)

Question 4

why does conduction begin at the SA node

Answer 4

1) it has a more positive resting membrane potential (can reach threshold faster)
2) has leaky sodium channels (sodium easily flows from the outside to the interior of the cells to reach threshold)

Question 5

parasympathetic nerves release

Answer 5

acetylcholine

Question 6

which nerve only affects heart rate

Answer 6

parasympathetic

Question 7

parasympathetic nerves release signals where and what does that mean for the heart

Answer 7

released only at SA and VA node (on the atrial side) which means it only decreases heart rhythm
=SLOWS THE SIGNAL DOWN (signal no longer transmitted to ventricles)

Question 8

sympathetic nerves release signals where and what does that mean for the heart

Answer 8

released through the atrial and ventricles which means it affects heart rate and contractility
=speeds signal-up

Question 9

what NT do sympathetic nerves release

Answer 9

norepinephrin

Question 10

What are the 2 reasons that HR increases after sympathetic activation

Answer 10

1) cells are more slightly depolarized (more positive membrane potential = easier to reach membrane potential)
2) stimulates sodium entry into the cell (steeper slope)

Question 11

what are the 2 reasons that HR decreases after parasympathetic activation?

Answer 11

1) cells are slightly hyperpolarized (more negative membrane potential=harder to reach potential)
2) slow is not as steep, less sodium entering in the xell

Question 12

what are the 5 functions of the cardiovascular system

Answer 12

1) Rapid substance transport to and from the tissues and organs of the body.
2) Rapid removal of metabolic waste (carbon dioxide, urea).
3) Distribution of hormones to the tissues/organs of destination.
4) Immune protection.
5) Temperature regulation.

Question 13

explain the function of temperature regulation in CV system

Answer 13

Blood vessels deliver heat from the core to the peripheral areas. Temperature regulation is done by the alteration of the blood flow through the skin. Vasodilation (dilation of arterioles and small arteries) and vasoconstriction (the opposite process) determines temperature locally.

Question 14

explain the function of immune protection of the CV system

Answer 14

Specialized blood cells called leucocytes (white blood cells) are used for antibody production.

Question 15

explain the function of the distribution of hormones to the tissues/organs of the destination in the CV system

Answer 15

Hormones are secretions of the endocrine glands that have specific effects on the functioning of other tissues/organs.
(ex: insulin is made in pancrease but needs to be delivered all over the body)

Question 16

explain the function of Rapid substance transport to and from the tissues and organs of the body in the CV system

Answer 16

transporting things like Oxygen, glucose, amino-acids, fatty acids, water, vitamins, drugs are carried along blood.

Question 17

explain the function of rapid removal of metabolic waste (carbon dioxide, urea) in the CV system

Answer 17

The circulatory system collects the metabolic waste products and delivers them to the excretory organs - e.g., the kidneys, lungs

Question 18

what are the 5 vessels of the circulatory system

Answer 18

1) conduction
2) distributing
3) resistance
4) exchange
5) capacitance

Question 19

true or false: the pump has an electrical system for regular running

Answer 19

true

Question 20

what permits rapid exchange between the tissues and the vascular channels

Answer 20

extensive system of thin vessels

Question 21

which is thicker and why: artery or vein

Answer 21

artery because it deals with more pressure

Question 22

what are the special features of the artery

Answer 22

muscular, highly elastic

Question 23

what are the special features of the arteriole

Answer 23

muscular, well innervation

(only 1 monolayer of muscle cells(

Question 24

what are the special features of capillaries

Answer 24

thin walled, highly permeable

only 1 single layer of endothelial cells where excahange happens

Question 25

what are the special features of venules

Answer 25

thin walled, with some smooth muscle

Question 26

what are the special features of veins

Answer 26

thin-walled (compared to arteries), fairly muscular, and distensible 1 or 2 layers or smooth muscles

Question 27

what is the function of the aorta

Answer 27

pulse dampening and distribution

Question 28

what is the function of large arteries

Answer 28

distribution

Question 29

what is the function of small arteries

Answer 29

distribution and resistance

Question 30

what is the function of arterioles

Answer 30

resistance (pressure/flow reg)

Question 31

what is the function of capillaries

Answer 31

exchange

Question 32

what is the function of the venules

Answer 32

exchange, collection and capacitance

Question 33

what is the function of veins

Answer 33

capacitance (blood vol)

Question 34

what is the function of the vena cava

Answer 34

collection

Question 35

Velocity of blood flow is BLANK related to the cross-sectional area of the vascular system

Answer 35

inversly

Question 36

is blood flow velocity slow or fast in capillaries and why

Answer 36

very slow | they have a large cross sectional area which makes conditions ideal for exchange of diffusible substances

Question 37

where is velocity of blood flow greatest

Answer 37

in the aorta

Question 38

rank these from fastest to slowest, | small veins, capillaries, aorta, aterioles

Answer 38

aorta arterioles small veins capillaries

Question 39

what is the equation for velocity of blood

Answer 39

blood flow/CSA

Question 40

what is the definition of blood flow

Answer 40

is the quantity of blood that passes a given point in the circulation in a given period of time.

Question 41

how is unit of blood flow usually expressed as

Answer 41

as milliliters (ml) or Liters (L) per minute.

Question 42

what is overall flow of an adult

Answer 42

is 5 liters/min which is the cardiac output.

Question 43

how does blood usually flow

Answer 43

streamlines with each layer of blood remaining the same distance from the wall, this type of flow is called laminar flow.

Question 44

what happens when laminar flow occurs

Answer 44

the velocity of blood in the center of the vessel is greater than that toward the outer edge creating a parabolic profile. =vectors in the same direction

Question 45

what are the causes of turbulent flow

Answer 45

high velocities sharp turns in the circulation rough surfaces in the circulation rapid narrowing of blood vessels diverstion into smaller streams

Question 46

there is more friction in laminar flow or turbulent

Answer 46

turbulent

Question 47

what type of flow is silent and which causes murmurs

Answer 47

laminar: silent turbulent: murmurs

Question 48

why are murmurs important

Answer 48

are important in diagnosing vessel stenosis, vessel shunts, and cardiac valvular lesions.

Question 49

what is blood flow to tissues controlled in relation to

Answer 49

tissue needs (at rest=equally distribution, during exercise: skeletal gets a lot of blood)

Question 50

what is cardiac output mainly controlled by

Answer 50

local tissue flow (it is the sum of all local blood flows)

Question 51

true or false: arterial pressure is controlled dependant of local blood flow control or cardiac output control.

Answer 51

false | independant

Question 52

what is the difference between blood flow and cardiac output

Answer 52

cardiac: amount of blood ejected per min blood flow: distribution of blood

Question 53

what generates blood flow

Answer 53

pumping action of the heart

Question 54

how does pressure arise

Answer 54

when flow is opposed by resistance

Question 55

what is the definition of BP and the formula

Answer 55

Blood pressure is the force exerted by the blood against any unit area of vessel wall. BP = CO x TPR

Question 56

where is systemic pressure the highest

Answer 56

aorta

Question 57

true or false: systemic pressure decreases through pathway and reaches 0 mm in right atrium

Answer 57

true

Question 58

where does the steepest drop in systemic BP occur

Answer 58

in arterioles

Question 59

the arterial blood pressure reflects what two factors of arteries close to the heart

Answer 59

Elasticity (compliance or distensibility) Volume of blood forced into them at any time

Question 60

blood pressure near the heart is called

Answer 60

pulsatile

Question 61

where does blood pressure change from pulsatile to continuous

Answer 61

arterioles

Question 62

def of systolic pressure and normal number

Answer 62

pressure exerted in aorta during ventricular contraction | Averages 120 mmHg in healthy adult

Question 63

what is the def of diastolic pressure

Answer 63

lowest level of aortic pressure

Question 64

what is pulse pressure

Answer 64

difference between systolic and diastolic pressure | Throbbing of arteries (pulse)

Question 65

what is the pressure that propels the blood to the tissues

Answer 65

mean arterial pressure

Question 66

true or false: systolic pressure propels blood to the tissues

Answer 66

false, MAP does

Question 67

what is the formula for MAP

Answer 67

MAP=diastolic pressure + 1/3 pulse pressure

Question 68

Pulse pressure and MAP both BLANK with increasing distance from heart

Answer 68

decline/decrease

Question 69

what is the normal range of capularry blood pressure

Answer 69

17-35 mm HG

Question 70

do we want high or low capillary pressure and why

Answer 70

low | Slow capillary flow allows adequate time for exchange between blood and tissues

Question 71

explain low pressure of capillaries and the effect on permeability

Answer 71

Most capillaries are very permeable, so low pressure forces filtrate into interstitial spaces

Question 72

true or false: the venous blood pressure changes a lot during cardiac cycle

Answer 72

false it changes little

Question 73

true or false; there is a small pressure gradient in venous BP (about 15)

Answer 73

true

Question 74

why is there low pressure in veins

Answer 74

Low pressure due to cumulative effects of peripheral resistance

Question 75

where does the energy of BP loss go

Answer 75

as heat

Question 76

explain low pressure in venous BP

Answer 76

travelling through systemic circulation it loses alot of velocity (slowed down by resistance in arteriole side)

Question 77

what junction do we see a large pressure drop

Answer 77

arteriole-capillary junction

Question 78

what is the definition of resistance

Answer 78

impedes blood flow in a vessel. The measure of the amount of friction blood encounters with vessel walls, generally in peripheral (systemic) circulation

Question 79

how can you calculate resistance

Answer 79

dividing the pressure difference between two points in a vessel by the vessel blood flow resistance = delta P/flow

Question 80

true or false: its better to have serial resistance cites in circulation

Answer 80

no its better parallel

Question 81

why is parallel resistance in circulation better

Answer 81

blood will travel where there is the least resistance so if one path is blocked it will move to another =ALLOWS REDIRECTION OF BLOOD TO WHERE ITS NEEDED

Question 82

what are the 3 important sources of resistance

Answer 82

Blood vessel diameter Total blood vessel length Blood viscosity

Question 83

what is the greatest influence on resistance

Answer 83

blood vessel diameter

Question 84

frequent changes in BLANK alter peripheral resistance

Answer 84

in diameter

Question 85

resistance varies inversely with BLANK power of vessel radius

Answer 85

with. 4th power

Question 86

example the relationship between vessel radius and resistance

Answer 86

increase diameter=increase blood flow= decrease in resistance ex: if diameter does from 1 to 2 then the flow goes from 1 to 16

Question 87

the resistance is very sensitive to changes in///

Answer 87

radius of a vessel

Question 88

if there is vasoconstriction, there is an increase or decrease in resistance

Answer 88

increase

Question 89

what are the major determinants of peripheral resistance

Answer 89

small radius arterior

Question 90

abrupt changes in diameter or fatty plaques from atherosclerosis have what effect on resistance

Answer 90

increase = disrupts laminator flow and causes turbulent flow =irregular flow motion=increases resistance

Question 91

what are the 2 factors that remain constant for resistance

Answer 91

blood viscosity and blood vessel length

Question 92

explain blood viscosity effect on resistance

Answer 92

The "stickiness" of blood due to formed elements and plasma proteins Increased viscosity = increased resistance

Question 93

explain blood vessel length effect on resistance

Answer 93

longer vessel =greater resistance

Question 94

do you have higher viscosity in summer or winter

Answer 94

summer

Question 95

what is poiseuille's law

Answer 95

flow = (pie)(pressure diff)(r)^4/8nl

Question 96

what is conductance and formula

Answer 96

is a measure of the blood flow through a vessel for a given pressure difference. Units ml/min per mmHg conductance = 1/resistance

Question 97

what is the equation for flow

Answer 97

flow=change in pressure diff/resistance

Question 98

what is flow through a blood vessel determined by

Answer 98

1) The pressure difference (∆P) between the two ends of the vessel 2) Resistance (R) of the vessel

Question 99

blood flow is BLANK to blood pressure gradient

Answer 99

directly proportional (ie: if a change in pressure increases, blood flow increases)

Question 100

blood flow is BLANK proportional to peripheral resistance

Answer 100

inversly | if R increase, blood flow decrease

Question 101

what is more important in influencing local blood flow because easily changed by altering blood vessel diameter

Answer 101

resistance

Question 102

if arterial pressure and venous pressure remain contant resistance decreases what happens to flow

Answer 102

increases

Question 103

if arterial and venous pressure stay constant resistance increases what happens to flow

Answer 103

decreases