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Physiology > Physiology Exam 3 - Cardiovascular System > Flashcards

Physiology Exam 3 - Cardiovascular System Flashcards

1
Q

What makes up the cardiovascular system?

A

heart and blood vessels

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2
Q

What makes up the circulatory system?

A

heart, blood vessels, and blood

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3
Q

What systems affect cardiovascular function?

A

endocrine, nervous, and urinary

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4
Q

Pulmonary circulation

A

carries deoxygenated blood from the right ventricle to the lung for gas exchange and back (right side of heart)

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5
Q

Systemic circulation

A

supplies oxygenated blood from the left ventricle to all tissues of the body and returns it to the heart (left side of heart)

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6
Q

Right and left ventricles

A
  • two inferior chambers
  • pump blood into the arteries
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7
Q

Right and left atria

A
  • two superior chambers
  • receive blood returning to the heart
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8
Q

Arteries

A

carry blood away from the heart

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9
Q

Veins

A

carry blood back to the heart

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10
Q

Capillaries

A

connect smallest arteries to smallest veins to create a circuit

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11
Q

What type of blood do arteries carry?

A

oxygenated blood

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12
Q

What type of blood do veins carry?

A

deoxygenated blood

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13
Q

What type of blood does the pulmonary artery carry?

A

deoxygenated blood

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14
Q

What type of blood does the pulmonary vein carry?

A

oxygenated blood

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15
Q

Where is the majority of the blood distributed in the body?

A

abdominal organs - small intestine and liver

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16
Q

Pressure

A

the force exerted by the blood, measured in mmHg

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17
Q

How does blood flow according to pressure?

A

from higher pressure to lower pressure

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18
Q

Flow

A

the volume of blood moved per unit time, measured in mL/min

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19
Q

Resistance

A

how difficult it is for blood to flow between two points at any given pressure difference; the measure of friction that impedes flow

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20
Q

F = change in P/R

A

flow rate is directly proportional to the pressure difference and inversely proportional to the resistance

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21
Q

What are factors that determine resistance?

A

blood viscosity, total blood vessel length, and blood vessel radius

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22
Q

Blood viscosity

A

friction between molecules of a flowing fluid; affected by water volume and total number of erythrocytes

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23
Q

Blood vessel length

A

remains constant

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24
Q

Blood vessel radius

A

not constant, inversely proportional to resistance; dilated vessels decrease resistance, while constricted vessels increase resistance

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25
Q

What are the layers of the heart wall (outer to inner)?

A

epicardium, myocardium (contains cardiomyocytes), endocardium

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26
Q

Cardiomyocytes

A

cardiac muscle cells arranged in layers

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27
Q

What happens to cardiomyocytes with every heart beat?

A

they contract in unison (no resting - 3 billion during lifespan)

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28
Q

Can the human body replace cardiomyocytes?

A

limited ability by specialized stem cells - only about 1% ability

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29
Q

Specialized cardiomyocytes

A

1% of cells, excitable but do not contract

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30
Q

Pacemaker cells

A

constitute a network, conducting system, electrical contact through all cardiomyocytes via gap junctions; initiate the heartbeat and spread an action potential rapidly throughout the entire heart

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31
Q

Sympathetic fibers

A

innervate the entire heart, release norepinephrine

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32
Q

Parasympathetic fibers

A

innervate special cells in the atria, release primarily acetylcholine

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33
Q

What is the order of cardiac rhythmic electrical signals?

A
  1. Sinoatrial (SA) node
  2. Atrioventricular (AV) node
  3. Atrioventricular (AV) bundle (bundle of His)
  4. Subendothelial conducting networks
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34
Q

What is another name for the SA node?

A

the pacemaker

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35
Q

What does the SA node do?

A

stimulates the two atria to contract almost simultaneously (reaches AV node in 50 ms)

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36
Q

What is the AV node structure?

A

thin cardiomyocytes with few gap junctions

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37
Q

What happens as the signal travels through the AV node?

A

it slows down (delayed 100 ms) to allow ventricles to fill

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38
Q

What happens as the signal reaches the AV bundle (bundle of His)?

A
  • the bundle splits into right and left branches that pass through the interventricular septum toward the apex
  • signals quickly travel through right and left AV bundle and reach the subendothelial conducting network
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39
Q

What is another name for the subendothelial conducting network?

A

Purkinje fibers

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40
Q

What is another name for the AV bundle?

A

bundle of His

41
Q

What is the subendothelial conducting network and what does it do?

A
  • nerve-like processes spread throughout ventricular myocardium
  • cardiomyocytes then pass the signal from cell to cell through gap junctions.
42
Q

What happens after the cardiomyocytes pass the signal from cell to cell?

A
  • ventricular systole occurs, progressing up from the apex of the heart (spiral arrangement of myocardium twists ventricles slightly)
43
Q

Sinus rhythm

A

normal heartbeat triggered by the SA node (typically 70 - 80 bpm)

44
Q

How often does the SA node fire?

A

every 0.8 sec (resting heartbeat = 75 bpm)

45
Q

Ectopic focus

A

a region of spontaneous firing other than the SA node (can govern heart rhythm if SA node is damaged) (20 - 40 bpm - cannot sustain life)

46
Q

Nodal rhythm

A

if the SA node is damaged, the heart rate is set by the AV node (set at 40 - 50 bpm)

47
Q

What is the resting potential of cardiomyocytes?

A

-90 mV

48
Q

What are the phases of cardiomyocyte potential?

A

depolarization, plateau, repolarization, and baseline

49
Q

What happens during the depolarization phase of cardiomyocytes?

A
  • voltage-gated Na+ channels open
  • Na+ rushes into the sarcoplasm
  • membrane rapidly depolarizes
  • action potential peaks at +30 mV
  • Na+ channels close quickly
50
Q

What happens during the plateau phase of cardiomyocytes?

A
  • voltage-gated Ca2+ channels open (slow); L-type channels (long lasting)
  • Ca2+ enters, triggering opening of Ca2+ channels on sarcoplasmic reticulum
  • Ca2+ (from SR) binds to troponin, triggering contraction
  • sustains contraction from expulsion of blood from the heart
51
Q

What happens during the repolarization phase of cardiomyocytes?

A
  • Ca2+ channels close
  • K+ channels open
  • rapid exit of K+ out of cell returns membrane to resting potential
52
Q

Why does the ventricular action potential have a long absolute refractory period?

A

to prevent wave summation and tetanus, which would stop the pumping of the heart

53
Q

What are the phases of SA node action potential?

A
  • pacemaker potential
  • depolarization
  • repolarization
54
Q

What occurs during the pacemaker potential?

A
  • starts at -60 mV
  • potential drifts upward from slow Na+ inflow through non-specific cation F-type channels (“funny” current)
  • pacemaker potential provides the SA node with automaticity (can induce themselves their own signal)
55
Q

What occurs during the depolarization of the SA node?

A
  • when the membrane reaches -40 mV, voltage-gated Ca2+ channels (T-type transient) and other types of Na+ channels open
56
Q

What occurs during the repolarization of the SA node?

A
  • voltage-gated K+ channels open
  • K+ leaves the cell
  • once K+ channels close, the pacemaker potential starts over
57
Q

What are artificial/cardiac pacemakers?

A

electronic devices that are implanted in the body to monitor heart rate and rhythm; gives heart electrical stimulation when it does not beat normally

58
Q

What is the most common sustained arrhythmia observed in the clinic?

A

A-fib

59
Q

What are the phases of the cardiac cycle?

A
  1. ventricular filling
  2. isovolumetric contraction
  3. ventricular ejection
  4. isovolumetric relaxation
60
Q

What is the cardiac cycle?

A

one complete contraction and relaxation of all four chambers of the heart

61
Q

What happens when ventricles relax?

A
  • they expand and the internal pressure falls
  • AV values (tricuspid and mitral) open, and blood flows into the ventricles
62
Q

What happens when ventricles contract?

A
  • they constrict and the internal pressure rises
  • AV valves close and the semilunar valves (aortic and pulmonary) open and blood flows into the aorta or pulmonary trunk
63
Q

What determines the opening and closing of valves?

A

changes in pressure

64
Q

What are the AV valves like when ventricles are relaxed?

A

limp

65
Q

What are the semilunar valves like when the ventricles are relaxed?

A

under pressure from blood in vessels

66
Q

Auscultation

A

listening to sounds made by the body

67
Q

What is the first heart sound called?

A

S1

68
Q

What is the second heart sound called?

A

S2

69
Q

What are two other heart sounds besides S1 and S2?

A

S3 and S4

70
Q

What describes the first heart sounds (S1)?

A
  • louder and longer “Lub”
  • occurs with the closure of AV valves
71
Q

What describes the second heart sounds (S2)?

A
  • softer and sharper “Dub”
  • occurs with the closure of semilunar valves
72
Q

What describes the S3 heart sound?

A
  • occurs after the S2 sound
  • called “ventricular gallop”
  • rarely heard in people over 30
73
Q

What describes the S4 heart sound?

A
  • occurs just before the S1 sound
  • called “atrial gallop”
  • results from the contraction of the atria pushing blood into a stiff or hypertrophic ventricle
  • indicates failure of the left ventricle
74
Q

When does ventricular filling occur?

A

during diastole

75
Q

When does isovolumetric contraction occur?

A

during systole

76
Q

When does ventricular ejection occur?

A

during systole

77
Q

When does isovolumetric relaxation occur?

A

during diastole

78
Q

How long does it take for the cardiac cycle to complete?

A

less than 1 second

79
Q

What happens during the ventricular filling phase of the cardiac cycle?

A
  • the ventricles expand and the pressure drops below that of the atria
  • the AV valves open and blood flows into the ventricles
80
Q

What are the phases of ventricular filling?

A

1a. Rapid ventricular filling - first one-third; S3 sound

1b. Diastasis - second one-third; slower filling; P wave starts

1c. Atrial systole - final one-third; atria contract

81
Q

What happens during the isovolumetric contraction phase of the cardiac cycle?

A
  • atria repolarize, relax and remain in diastole for the rest of the cardiac cycle
  • ventricles finish depolarizing, causing QRS complex, and begin to contract
  • AV valves close
  • S1 occurs at the beginning
82
Q

What does the term “isovolumetric” indicate in isovolumetric contraction?

A
  • pressures in the aorta and pulmonary trunk are still greater than in ventricles
  • all four valves are closed and the blood cannot go anywhere
83
Q

What happens during the ventricular ejection phase of the cardiac cycle?

A
  • begins when ventricular pressure exceeds arterial pressure and the semilunar valves open
  • pressure peaks in the left ventricle at 120 mmHg and 25 mmHg in the right
  • first: rapid ejection - blood spurts out quickly
  • then: reduced ejection - slower flow with lower pressure
  • ejection corresponds to the plateau phase of the cardiac action potential (200 to 250 ms)
  • T wave of EKG occurs late in this phase
84
Q

What happens during the isovolumetric relaxation phase of the cardiac cycle?

A
  • T wave ends and ventricles begin to expand
  • backward flow of blood from the aorta and pulmonary trunk closes the semilunar valves
  • S2 heart sound occurs
85
Q

What is the End-systolic volume?

A

60 mL

86
Q

What is the End-diastolic volume?

A

130 mL

87
Q

What is congestive heart failure?

A
  • failure of either ventricle to eject blood effectively
  • common cause: heart wall weakened by ischemia
  • symptoms depend on which ventricle is failing
88
Q

What occurs because of left ventricular failure?

A
  • the volume of blood from the right ventricle exceeds the left ventricular output
  • pressure backs up and blood backs up into the lungs causing pulmonary edema
  • shortness of breath or a sense of suffocation
89
Q

What occurs because of right ventricular failure?

A
  • volume of blood from the left ventricle exceeds the right ventricular output
  • pressure backs up and blood backs up in the vena cava causing systemic edema
  • liver enlargement, ascites (fluid in abdomen), jugular veins distension, swelling of fingers, ankles and feet
  • eventually leads to total heart failure
90
Q

What is the only treatment for total heart failure?

A

heart transplant

91
Q

What are heart rhythm and contraction controlled by?

A

cardiac centers located in the medulla oblongata

92
Q

Cardioacceleratory center

A
  • sends sympathetic innervation via that cardiac nerves
  • increases heart rate and contraction strength
93
Q

Cardioinhibitory center

A
  • sends parasympathetic innervation via the vagus nerve
  • slows heart rate
94
Q

Cardiac output

A

the amount of blood ejected by each ventricle in 1 minute

95
Q

What is the equation for cardiac output?

A

CO = heart rate x stroke volume

96
Q

What is the cardiac output at rest?

A

4 to 6 L/min

97
Q

What is the cardiac output with vigorous exercise?

A

21 L/min (fit person) or 40 L/min (world-class athlete)

98
Q

Cardiac reserve

A

the difference between a person’s maximum and resting cardiac output (increases with fitness, decreases with disease)

Physiology (6 decks)

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