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BRS Physiology > Cardio > Flashcards

Cardio Flashcards

1
Q

Name the vessel - thick walled, extensive elastic and smooth muscle, under high pressure

A

Arteries

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2
Q

Name the vessel - site of highest resistance in the cardiovascular system

A

Arterioles

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3
Q

Name the vessel - largest total cross sectional and surface area

A

Capillaries

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4
Q

Name the vessel - low pressure, highest proportion of blood in the cardiovascular system

A

Veins

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5
Q

Express velocity as an equation

A

V = Q/A

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6
Q

Express blood flow as an equation

A

Q = delta P/ R OR CO = MAP - RAP / TPR

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7
Q

What drives blood flow?

A

pressure gradient - flows from high pressure to low pressure

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8
Q

Poiseuille’s Equation

A

R = 8nl / pie r^4

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9
Q

systemic circulation illustrates what type of resistance?

A

parallel resistance (1/Rtotal = 1/Ra + 1/Rb + ….. 1/Rn)

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10
Q

Arteries added in parallel causes total resistance to….

A

decrease

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11
Q

arrangement of blood vessels within an organ illustrates what type of resistance?

A

series resistance (R total = R artery + R arterioles + R capillaries)

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12
Q

What is the same in each parallel artery?

A

pressure

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13
Q

Each blood vessel or set of blood vessels in series receives the ________ amount of total blood flow

A

same

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14
Q

What does Reynold’s number predict?

A

whether blood flow will be laminar or turbulent

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15
Q

Velocity of blood is ___ at the wall of a vessel and highest at the _____ of the vessel

A

0; center

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16
Q

Shear is highest at the _____ of the blood vessel

A

wall

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17
Q

Compliance is inversely related to _____

A

elastance (higher elastance = lower compliance)

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18
Q

Express compliance as an equation

A

C = V/P

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19
Q

Compliance is greatest for what type of vessels?

A

Veins

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20
Q

What happens to pressure as blood flows through the systemic circulation?

A

pressure decreases progressively b/c of the resistance to blood flow

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21
Q

The largest decrease in pressure occurs across which vessels?

A

Arterioles (b/c they have the highest resistance; recall Q = delta P / R)

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22
Q

Pulse pressure is defined as

A

Systolic pressure - diastolic pressure

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23
Q

The most important determinant of pulse pressure is ?

A

Stroke volume

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24
Q

Define Mean arterial pressure

A

average arterial pressure with respect to time (MAP = diastolic + 1/3 pulse pressure)

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25
Q

How can left atrial pressure be estimated?

A

by pulmonary wedge pressure

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26
Q

PR interval

A

beginning of R wave to beginning of Q wave

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27
Q

What causes variation of the PR interval?

A

conduction velocity through the AV node

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28
Q

A decreased PR interval (increased conduction velocity through the AV node) can be caused by the stimulation of ?

A

the sympathetic nervous system

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29
Q

QT interval

A

beginning of Q wave to end of T wave; entire period of depolarization and repolarization of the ventricles

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30
Q

ST segment

A

end of S wave to beginning of T wave; period when ventricles are depolarized

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31
Q

T wave represents?

A

ventricular repolarization

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32
Q

Phase 0, the upstroke of the ventricular AP is caused by?

A

transient increase in Na+ conductance; INWARD Na+ current depolarizes membrane

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33
Q

Phase 1, the initial repolarization of the ventricular AP is caused by what two factors?

A

movement of K+ ions OUT of the cell and decrease in Na+ conductance INWARD

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34
Q

Phase 2, the plateau of the ventricular AP is caused by ?

A

transient increase in Ca2+ conductance – INWARD Ca2+ current and increase in K+ conductance OUT; balanced causing plateau

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35
Q

Phase 3, repolarization of the ventricular AP is caused by?

A

Ca2+ conductance decreases and K+ conductance predominates - large OUTWARD K+ current

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36
Q

Phase 0, upstroke of SA node AP is caused by?

A

increase in Ca2+ conductance – INWARD current

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37
Q

Phase 3, repolarization of SA node AP is caused by?

A

increase in K+ conductance – OUTWARD current

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38
Q

Phase 4, slow depolarization of the SA node AP is caused by?

A

increase in Na+ conductance – INWARD Na+ current (If)

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39
Q

Phase 4 of the SA node AP accounts for?

A

pacemaker activity of the SA node

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40
Q

What two phases are not present in the SA node AP?

A

Phase 1 and 2

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41
Q

Conduction velocity depends on what?

A

size of the inward current during the upstroke of the AP

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42
Q

Where is conduction velocity the fastest and slowest?

A

Purkinje system; AV node (to allow ventricals to fill)

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43
Q

What is the absolute refractory period? when does it begin and end?

A

Begins with upstroke of AP and ends after plateau; time during which no AP can be initiated regardless of inward current supplied

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44
Q

What is the effective refractory period?

A

a conducted AP cannot be elicited

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45
Q

What is the relative refractory period?

A

AP can be elicited, but more than the usual inward current is required

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46
Q

Negative chronotropic effect

A

HR decreases due to decrease rate of phase 4 depolarization; decreased inward Na+ current

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47
Q

Negative dromotropic effect

A

decreases conduction velocity through the AV node; increases PR interval; decreased inward Ca2+ current and increased outward K+ current

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48
Q

Positive chronotropic effect

A

HR increases due to increase rate of phase 4 depolarization; increased inward Na+ current

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49
Q

Positive dromotropic effect

A

increases conduction velocity through the AV node; decreases PR interval; increased inward Ca2+ current

50
Q

Gap junctions in heart muscle allow it to behave as a ?

A

electrical syncytium

51
Q

T/F mitochondria is more numerous in cardiac muscle than in skeletal muscle?

A

T

52
Q

During the plateau phase of the AP Ca2+ enters through what type of calcium channels?

A

L-type calcium channels (dihydropyridine receptors)

53
Q

Ca2+ that entered through the dihydropyridine receptors in turn activate what channels?

A

triggers the release of more calcium from the SR through calcium release channels (ryanodine receptors) – Ca2+ induced Ca2+ release

54
Q

When calcium binds to troponin C what is moved out of the way?

A

tropomyosin

55
Q

inotropy refers to …

A

contractility

56
Q

How does sympathetic stimulation via B1 receptors increase the force of contraction ?

A

increases INWARD Ca2+ current during plateau of cardiac AP; also increases activity of Ca2+ pump of the SR

57
Q

How does digitalis increase force of contaction?

A

block Na/K ATPase -> intracellular Na+ increases, diminishing Na+ gradient -> Na+/Ca2+ exchange is diminished due to loss of gradient -> increase in intracellular Ca2+

58
Q

Preload can be defined as ..

A

end-diastolic volume, which is related to right atrial pressure

59
Q

Afterload is considered what for the LV and RV?

A

aortic pressure and pulmonary artery pressure

60
Q

What determines the maximum tension/force of contraction?

A

sarcomere length – determines max. number of cross-bridges that can form between actin and myosin

61
Q

increased contractility leads to what changes as shown on a pressure - volume loop

A

increased stroke volume which leads to a decrease in end systolic volume

62
Q

Mean systemic pressure is increased by …

A

an increase in blood volume or by a decrease in venous compliance (blood is shifted from the veins to the arteries)

63
Q

Mean systemic pressure is decreased by …

A

a decrease in blood volume or by an increase in venous compliance (blood is shifted from the arteries to the veins)

64
Q

The slope of the venous return curve is determined by?

A

resistance of the arterioles

65
Q

When TPR is decreased for a given RAP …

A

there is an increase in venous return (vasodilation of arterioles allows more blood to flow from arteries to veins)

66
Q

When TPR is increased for a given RAP …

A

there is a decrease in venous return to the heart (vasoconstriction of the arterioles decreases blood flow from the arteries to the veins and back to the heart)

67
Q

Affects of positive inotropic agents as seen on a cardiac output curve

A

produce increased contractility and increased CO; steady state point shifts to a higher CO and a lower RAP (due to more blood being ejected)

68
Q

Does changes in blood volume or venous compliance change the venous return curve or the cardiac output curve?

A

venous return curve

69
Q

Increases in blood volume or decreases in venous compliance leads to?

A

increase in mean systemic pressure; venous return curve shifts to the right in a parallel fashion; new equilibrium point is reached where both the cardiac output and RAP are increased

70
Q

Decreases in blood blood volume or increases in venous compliance leads to?

A

decrease in means systemic pressure; venous return curve shifts to the left in a parallel fashion; new equilibrium point is reached where both cardiac output and RAP are decreased

71
Q

Changes in TPR alters the cardiac output curve or the venous return curve?

A

both simultaneously

72
Q

Increased TPR causes …

A

a decrease in both cardiac output and venous return; right atrial pressure is unchanged

73
Q

Decreased TPR causes

A

an increase in both cardiac output and venous return; right atrial pressure is unchanged

74
Q

Express stroke volume as an equation

A

Stroke volume = end diastolic volume - end systolic volume

75
Q

Express cardiac output as an equation

A

CO = SV x HR

76
Q

What is a normal ejection fraction?

A

55%

77
Q

What is an ejection fraction?

A

fraction of end diastolic volume ejected in each stroke volume (ejection fraction = SV / EDV

78
Q

What is stroke work?

A

work the heart performs on each beat (stroke work = pressure x volume)

79
Q

What are the primary energy source for stroke work?

A

Fatty acids

80
Q

What is cardiac oxygen consumption directly related to?

A

amount of tension developed by the ventricles

81
Q

Cardiac oxygen consumption is increased by what 4 factors?

A

increased after load, increased size of heart, increased contractility, increased HR

82
Q

Fick Equation for Cardiac output is

A

Cardiac ouput = O2 consumption / [O2] pulmonary vein - [02] pulmonary artery

83
Q

What is the a wave on the venous pulse curve?

A

the increase in atrial pressure caused by atrial systole

84
Q

What is the fourth heart sound? is it normally audible?

A

filling of the ventricle by atrial systole; not audible in normal adults

85
Q

What corresponds to the first heart sound?

A

closing of AV valves (ventricular pressure becomes greater than atrial pressure)

86
Q

Why might the first heart sound be split?

A

mitral valve closes before the tricuspid valve

87
Q

What corresponds to the second heart sound?

A

closure of the aortic and pulmonic valves

88
Q

What corresponds to the third heart sound? is it normally audible?

A

rapid flow of blood from the atria into the ventricles causes the third heart sound; normal in children but in adults is associated with disease

89
Q

What is the longest phase of the cardiac cycle?

A

reduced ventricular filling

90
Q

What is responsible for the minute to minute regulation of arterial blood pressure?

A

baroreceptor reflex

91
Q

Where are baroreceptors located?

A

within the walls of the carotid sinus near the bifurcation of the common carotid arteries

92
Q

A decrease in arterial pressure will lead to what in the carotid sinus?

A

decrease stretch

93
Q

A decrease in renal perfusion pressure causes what event to occur?

A

juxtaglomerular cells of the afferent arteriole to secrete renin

94
Q

What does renin do?

A

catalyzes conversion of angiotensinogen to angiotensin I in the plasma

95
Q

What catalyzes conversion of angiontensin I to angiotensin II in the lungs?

A

Angiotensin converting enzyme (ACE)

96
Q

MOA and use of ACE inhibitors? (ex. captopril)

A

block conversion of angiotensin I to angiotensin II leading to decrease in blood pressure

97
Q

MOA and use of Angiotensin receptor (AT1) antagonists (ex. Losartan)

A

block the action of angiotensin II at its receptor and decrease blood pressure

98
Q

4 effects of angiotensin II

A

secretion of aldosterone; increases Na+/H+ exchange in the PCT; increases thirst; vasoconstriction of arterioles

99
Q

Function of aldosterone

A

increases Na+ reabsorption by the renal distal tubule

100
Q

chemoreceptors in the carotid and aortic bodies sense?

A

decreases in PO2

101
Q

2 effects of vasopressin that tend to increase blood pressure toward normal

A

potent vasoconstrictor that increases TPR by activating V1 receptors on arterioles; increases water reabsorption by the renal distal tubule and collecting ducts by activating V2 receptors

102
Q

Where and when is Atrial natriuretic peptide released?

A

released from the atria in response to an increase in blood volume and atrial pressure

103
Q

Actions of ANP

A

relaxation of vascular smooth muscle, dilation of arterioles, decreased TPR, increased excretion of Na+ and water by the kidney, inhibits renin secretion

104
Q

how do large water-soluble substances cross the capillary wall?

A

pinocytosis

105
Q

how do lipid soluble substances like O2 and CO2 cross the capillary wall?

A

simple diffusion

106
Q

how do small water soluble substances like water, glucose, and amino acids cross the capillary wall?

A

water-filled clefts between endothelial cells

107
Q

Starling equation

A

Jv = Kf [(Pc - Pi) - (piec - piei)]

108
Q

nitric oxide is one form of ?

A

endothelium-derived relaxing factor (EDRF)

109
Q

What organs exhibit autoregulation?

A

heart, brain, kidney

110
Q

What is active hyperemia?

A

blood flow to an organ is proportional to its metabolic activity

111
Q

What is reactive hyperemia?

A

an increase in blood flow to an organ that occurs after a period of occlusion of flow

112
Q

the most important mechanism of controlling blood flow in the skin

A

sympathetic control - temperature regulation

113
Q

effect of histamine on blood flow

A

arteriolar dilation and venous constriction leads to increased Pc and increased filtration out of capillaries causing edema

114
Q

effect of bradykinin on blood flow

A

arteriolar dilation and venous constriction produces increased filtration out of the capillaries causing edema

115
Q

Is thromboxane A2 a vasodilator or vasoconstrictor?

A

vasoconstrictor

116
Q

Coronary circulation is almost entirely controlled by?

A

local metabolic factors - hypoxia and adenosine

117
Q

Cerebral circulation is almost entirely controlled by?

A

local metabolic factors - CO2

118
Q

What is the primary regulator of blood flow to skeletal muscle at rest?

A

sympathetic innervation

119
Q

What type of adrenergic receptors are found on blood vessels of skeletal muscle and what effects to they have?

A

alpha 1 - vasoconstriction

beta 2 - vasodilation

120
Q

What is the primary regulator of blood flow to skeletal muscle during exercise?

A

local metabolic mechanisms - lactate, adenosine, K+

BRS Physiology (1 decks)

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