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OSSF > Cardio > Flashcards

Cardio Flashcards

1
Q

What is the purpose of the cardiac valves?

A

to ensure unidirectional flow

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2
Q

What are the two valves on the left side of the heart? (systemic circulation)

A

mitral valve and aortic valve

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3
Q

What are the two valves on the right side of the heart? (pulmonary circulation)

A

tricuspid valve and pulmonic valve

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4
Q

what is the main function of pulmonary circulation?

A

gas exchange

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5
Q

what is the main function of the systemic circulation?

A

transport O2 to and from organs/tissues

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6
Q

The two circulatory systems are in ____

A

series

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7
Q

Define a portal system

A

when blood passes through two consecutive capillary networks

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8
Q

List the three main adult portal systems

A

-hepatic
-kidneys
-anterior pituitary

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9
Q

What is the major blood supply to the liver? ~75%

A

the hepatic portal vein

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10
Q

of the total blood volume, what percent is in the systemic circulation at a time?

A

85%

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11
Q

True/False: distribution of cardiac output is proportional with organ mass at rest

A

false

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12
Q

What is the major site of arterial pressure regulation?

A

arterioles

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13
Q

What vessel serves as the major blood reservoir?

A

veins

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14
Q

Capillaries have the ____ cross sectional diameter per vessel, but the ______ cross sectional diameter when combines

A

smallest, largest

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15
Q

Why are pulmonary circulatory pressure lower than systemic?

A

to ensure gas diffusion

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16
Q

True False: fetal lungs don’t perform gas exchange

A

true

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17
Q

What are the two shunts in a fetal heart

A

ductus arteriosis and foramen ovale

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18
Q

Why does the heart have to have autoregulation to maintain coronary blood flow during high heart rates?

A

because during systole, the coronary arteries are compressed and blood flow decreases

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19
Q

Where does the cardiac action potential originate?

A

the SA node

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20
Q

Describe how cardiac muscle contraction differ from skeletal?

A

-linked end to end by intercalated discs which contain gap junctions
-shorter and branched
-action potentials can be propagated from cell to cell

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21
Q

How are action potentials propagated from atria to ventricles?

A

funneled through the AV node

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22
Q

True/False: nerves are required for conduction of electrical activity through the heart

A

false

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23
Q

What is the importance of myocyte bifurcation?

A

as AP are conducted from cell to cell activity spreads throughout the cells of the heart

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24
Q

What are the two types of cardiac muscle cells?

A

-Contractile
-Conductiong

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25
Q

What is autorhythmicity of conduction myocytes?

A

generation of spontaneous APs by undergoing slow depolarization until threshold is reached

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26
Q

What are the three components of the conduction system in the heart?

A

-AV node, the bundle of His, and purkinje fibers

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27
Q

What are the two main functions of the conduction system

A

-Delays impulse conduction from the atria to the ventricles which allows the ventricles to fill properly
-faster conduction that through gap junctions, so the whole ventricular mass can contract simultaneously

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28
Q

What is the annulus fibrosus? what is its function?

A

it acts like an electrical insulator, it enforces the passage of the electrical signal through the AV node which slows them down

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29
Q

Briefly describe the sequence of activation of the heart

A

-first cells reach threshold in the SA node
-APs are conducted to the AV node through atrial myocytes
-conduction slowly through the AV node
-from the AV node, APs are conducted through purkinje fibers to the bottom of the ventricles
-the bundle splits into right and left branches and activates myocytes in the left and right ventricles
-ventricles contract from apex to base

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30
Q

Describe the generation of action potentials in the SA node

A

-f channels are open and permeable to Na and K, Na flows in
-the membrane slowly depolarizes, the f channels close, the voltage gated Ca channels open, Ca flows into the cell, cell depolarizes further, threshold is reached
-another type of Ca channel opens, Ca flows into the cell, causing steep depolarization
-Ca channels close, K channels open, K leaves cell, repolarization occurs
-K channels close at ~65mV

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31
Q

What is the plateau phase of the cardiomyocyte due to?

A

opening of Ca channels which slows repolarization

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32
Q

What are two main differences between excitation-contraction coupling in cardiomyocytes and skeletal muscle?

A

-Ca release from the SR is induced by Ca in the cytosol not directly due to the action potential
-the long depolarization leads to an absolute refractory period that lasts for almost as long as the contraction.

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33
Q

what is chronotropy

A

heart rate

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34
Q

what is inotropy

A

contractility

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35
Q

What neurotransmitter is released by the SNS and what is its affect on the heart rate

A

Norepinephrine, SA node is depolarized to threshold more frequently

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36
Q

What neurotransmitter is released by the PNS? what is its affect on the heart rate? why what two mechanisms?

A

Acetylcholine. SA node depolarizes to threshold less frequently. it does so by decreasing f-channel current, and increases conductance of K out of the cell which hyperpolarizes the cell

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37
Q

How does the SNS affect inotropy?

A

Ca2+ channel open time is prolonged which means more Ca entering the cell, which yields more forceful contraction

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38
Q

How do cardiac glycosides affect contractility? how?

A

digitalis increases the force of cardiac contraction by slowing the removal of Ca2+ from the cytosol

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39
Q

What is circulating troponin I and T a biomarker for?

A

cardiac injury

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40
Q

How do ECGs work?

A

measures the tiny potential differences on the surface of the body that reflect the electrical activity of the heart.

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41
Q

Where should electrodes be placed in animals to get the largest amplitude ECG recording?

A

The net depolarization moving through the ventricles is moving toward the left hind leg

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42
Q

What is the physiological basis of the P wave?

A

depolarization of the atria

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43
Q

What is the physiological basis of the QRS complex?

A

depolarization of the ventricles

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44
Q

What is the physiological basis of the Q wave?

A

depolarization of the ventricle septum

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45
Q

What is the physiological basis of the S wave

A

depolarization of the base of the left ventricle

46
Q

What is the physiological basis of the T wave

A

repolarization of the ventricles

47
Q

What cardiac events are not visible on ECG?

A

repolarization of the atria and depolarization/repolarization of the conducting system

48
Q

What does the PQ interval represent?

A

the time it takes an AP to go from the SA node to the ventricle. aka conduction time through the AV node

49
Q

What does the QT interval represent?

A

time from onset of ventricular depolarization to end of ventricular repolarization

50
Q

When are AV valves open?

A

when Patria> Pventricle

51
Q

When do AV valves close?

A

Pventricle > Patria

52
Q

When is the aortic valve closed?

A

Paorta > Pventricle

53
Q

When is the aortic valve open?

A

Pventricle > Paorta

54
Q

What are the two main phases of the cardiac cycle? and what events are they in reference to?

A

Diastole: ventricular relaxation
Systole: ventricular contraction

55
Q

What are the 3 parts of diastole?

A

First 1/3:rapid filling with blood that has accumulated in the atria
Middle 1/3: filling with blood flowing straight from the venous return
Final 1/3: filling with blood from atrial contraction

56
Q

Define isovolumetric contraction

A

the brief moment where the pressure n the aorta is higher than the ventricle, so the aortic and pulmonic valves are closed and the ventricles contract against a fixed volume

57
Q

Define isovolumetric relaxation

A

once the ventricle starts to relax and the pressure falls below the aorta/pulmonary artery, the aortic/pulmonic valves close, and once again both valves are closed for a brief moment

58
Q

Describe the cardiac cycle

A

Blood fills the artia, the pressure causes the AV valves to open, ventricles fill and the pressure causes AV valves to close, then once the ventricular pressure exceeds the aortic/pulmonary artery pressures the corresponding valves open and blood is pumped out of the ventricles

59
Q

What is the difference in resting heart rates in individuals due to?

A

difference in vagal tone (PNS mediated control of the heart)

60
Q

What is end diastolic volume?

A

the vol of blood in the ventricles at the end of diastole

61
Q

What is end systole volume?

A

the volume of the ventricle at the end of systole

62
Q

True/False: up to a certain limit, increase in EDV automatically results in a proportional increase in SV

A

true

63
Q

What is Starlings Law of the Heart?

A

The intrinsic regulatory mechanism that enables the two ventricles to continuously adjust their stroke volumes to match each other. “more in=more out”

64
Q

What is the main function of arterioles?

A

vasoconstriction/dilation to regulate blood flow into capillaries

65
Q

What is the only thing that can be regulated to influence vascular resistance?

A

radius of the blood vessels

66
Q

Where is the highest and slowest speed of flow in tube during laminar flow?

A

the slowest moving molecules are closest to the wall and the fastest is in the center of the tube

67
Q

What is Reynolds number?

A

a dimensionless number that is used to predict whether blood flow will be laminar or turbulent

68
Q

define MAP

A

mean arterial pressure is the pressure driving blood trough the tissues

69
Q

define TPR

A

the resistance to blood flow exerted by the entire systemic circulation is called the total peripheral resistance

70
Q

When is MAP closest to diastolic pressure?

A

at rest

71
Q

When is MAP closest to systolic pressure?

A

at high heart rates because the diastolic phase is shortened more than the systolic phase when heart rate increases

72
Q

Define pulse pressure

A

the difference between systolic and diastolic pressures

73
Q

What is the amplitude of the pulse pressure dependent on?

A

heart rate and stroke volume, the elasticity of the arteries, and the total peripheral resistance

74
Q

What are 4 factors that can affect arterial blood pressure?

A

-cardiac output
-total peripheral resistance (TPR)
-elasticity of the blood vessels
-blood volume (acute changes)

75
Q

What 3 ways is can arteriolar diameter be regulated?

A

-Sympathetic innervation
-Neurohormonal regulation
-Autoregulation

76
Q

Describe sympathetic regulation of arteriolar diameter

A

ending of nerve fibers release Norepinephrine, bind to alpha adrenergic receptors, depolarization, Ca2+ influx, vasoconstriction

77
Q

Describe neurohormonal regulation of arteriolar diameter

A

occurs mainly via epinephrine and angiostensin II
-angeotensin II causes constriction of arterioles except in the brain and heart
-epinephrine constricts the arterioles in most organs through activation of alpha adrenergic receptors

78
Q

What are the two types of autoregulation of arteriolar diameter?

A

metabolic and pressure

79
Q

Describe metabolic autoregulation of arteriolar diameter

A

metabolic by products cause local vasodilation

80
Q

Describe pressure autoregulation of arteriolar diameter

A

when arterial pressure falls, vascular smooth muscle cells in some organs relax and vice versa. only some organs are very sensitive to acute changes in blood flow

81
Q

What are the roles of endothelial cells in arteriolar diameter autoregulation?

A

When the cells are affected by local changes such as pO2 and stretch, they release substances that act locally such as nitric oxide and prostacylin

82
Q

capillaries contain what percent of circulating blood?

A

5%

83
Q

why do capillaries have the slowest velocity of blood flow?

A

to allow sufficient time for gas exchange

84
Q

What two things constitute the capillary wall?

A

basal lamina and a single layer of epithelium

85
Q

What does capillary density correlate with?

A

rate of metabolism of the tissue

86
Q

What is a pericyte and what is its purpose?

A

a cell that wraps around capillaries and communicate with the endothelial cells. they secrete substances that stimulate the endothelial cells to differentiate, multiply, and angiogenesis, they also regulate glomerular blood glow and store vit A in the liver

87
Q

What are the 3 types of capillaries and where are they?

A

-Continuous: most common type
-Fenestrated: occurs in organs whose functions depend on extensive movement of material across capillary walls
-Discontinuous: large diameter capillaries with fenestrae large enough for cells and large proteins to pass through.

88
Q

What is hydrostatic pressure in capillaries determined by?

A

by arterial and venous pressures and decreases along the length of the capillary

89
Q

What is effective osmotic pressure (oncotic) of capillary blood due to?

A

presence of large plasma proteins

90
Q

Why does capillary oncotic pressure oppose filtration?

A

because proteins cannot cross the endothelial wall of the capillary

91
Q

normally, do capillaries favor filtration or absorption?

A

filtration

92
Q

Under what capillary conditions will you have edema?

A

dilation of the arterioles (increasing hydrostatic pressure) or reduction in plasma proteins (decrease in oncotic pressure)

93
Q

Under what capillary conditions is absorption favored?

A

constriction of the arterioles or reductions in arterial pressure

94
Q

why is ~90% of the filtered fluid reabsorbed by the capillary eventually?

A

because hydrostatic pressure decreases down the length of the capillary but oncotic pressure remains the same so absorption is favored

95
Q

What is the purpose of lymphatics?

A

overall function of the lymphatic system is to regulate the distribution of the extracellular fluid

96
Q

how do lymphatics perform their functions?

A

lympatic capillaries possess one way flap valves that permit interstitial fluid and macromolecules to enter but not leave

97
Q

where do lymphatic capillaries drain?

A

they eventually merge into the thoracic duct which empties lymph into large veins usually the internal jugular

98
Q

Why must MAP remain within a relatively narrow range?

A

to preserve blood supply to vital organs and prevent damage to the heart and blood vessels

99
Q

What is the SNS and PNS affects on chronotropy

A

(HR) occurs at the SA node
SNS: increases
PNS: decreases

100
Q

What is the SNS and PNS affects on dromotropy

A

(conduction velocity) at the AV node
SNS: increases
PNS:decreases

101
Q

What is the SNS affects on inotropy

A

(contractility) in the atria/ventricles
SNS: increases amount of Ca2+ on so a stronger contraction

102
Q

What is the SNS affect on lusitropy?

A

(relaxation) in the atria/venticles
SNS: quicker Ca2+ resequestration

103
Q

How does the baroreceptor reflex regulate arterial blood pressure?

A

allows for dynamic, moment-to-moment regulation

104
Q

what two subsequent steps in the baroreceptor reflex allows for return to homeostasis of arterial blood pressure?

A

-change of radius of arteries (vascoconstriction/dilation)
-increase/decrease cardiac output

105
Q

baroreceptors are mechanoreceptors that mainly operate at high pressure, which sensors are active at low pressure or small changes in pressure?

A

volume sensors

106
Q

stimulation of volume receptors will result in what 3 effects?

A

-Direct effect: release atrial natriuretic peptide from atrial myocytes which increases natiuresis which reduces blood volume
-Direct effect:renal vasodilation, increased diuresis, reduced blood volume
- signal hypothalamus to decrease the production of vasopressin (aka antidiuretic hormone)

107
Q

What occurs in the CV system when chemoreceptors are activated?

A

Primary effects is to increase pulmonary activity
Secondary effects is to stimulate CV activity, so increase SNS and thus increase MAP

108
Q

what three hormonal pathways are involved in the long term regulation of MAP and blood volume?

A

-Renin-angiotensin-aldostrone
-ADH (vasopressin)
-Natriuretic peptides

109
Q

Describe the short term and long term regulatory mechanisms of hemorrhage

A

-Initially arterial pressure drops so responses are aimed at maintaining perfusion to vital organs and normalize arterial pressure
-long term goal is to restore normal blood volume

110
Q

what are the effects of vasopressin?

A

causes vasoconstriction and water reabsorption in kidney

111
Q

what are 7 locally acting factors governing blood flow though capillary beds?

A

-Histamine
-bradykinin
-PGI2
-PGE2
-TXA2
-LTs
-NO

OSSF (37 decks)

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