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Physiology > Cardiovascular System > Flashcards

Cardiovascular System Flashcards

1
Q

The secondary functions of the CVS (3)

A
  1. Thermoregulation
  2. Distribution of hormones to target cells
  3. Immunity (distribution of body’s defense mechanisms)
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2
Q

Intercalated discs are something unique to ___ muscle

A

Cardiac

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3
Q

Cardiac muscle has these things in common with skeletal muscle (3)

A
  1. Striated appearance
  2. Troponin and tropomyosin present
  3. T-tubule system and associated Ca2+-loaded sarcoplasmic reticulum
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4
Q

Cardiac muscle has these 2 things in common with smooth muscle

A
  1. Gap junctions

2. Single nucleus

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5
Q

A structure in cardiac muscle by which two adjacent cells are attached (Hint: Cell type thing)

A

Desmosomes

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6
Q

The connection of cardiac muscle cells by intercalated discs, gap junctions, and desmosomes forms a ____

A

Functional syncytium

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7
Q

The cardiac cycle consists of these two elements

A

Diastole (Ventricles relax, atria fill w/blood)

Systole (Ventricles contract - pump blood to aorta/pulmonary arteries)

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8
Q

The conduction system of the heart consists of these 5 elements:

A
  1. Sinoatrial node (SA)
  2. Atrioventricular node (AV)
  3. Bundle of His (AV bundle)
  4. Right and Left bundle branches
  5. Purkinje fibers
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9
Q

The resting membrane potential of cardiac muscle cells is approximately ___

A

-85 mV (millivolts)

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10
Q

Something unique to ___ muscle cells is that their action potential is of long duration

A

Cardiac

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11
Q

Action potential duration varies from 150 msec in ___, to 250 msec in ____, to 300 msec in ____

A

Atria, ventricles, purkinje fibers

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12
Q

What is mainly responsible for the “plateau” phase of the cardiac action potential?

A

The prolonged opening of slow calcium-sodium channels

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13
Q

The threshold potential in cardiomyocytes is approximately ___

A

-70 mV

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14
Q

Phase 4 (the return to resting membrane potential) is completed by these 3 things:

A
  1. Ca2+-ATPase
  2. Na+/Ca2+ exchanger
  3. Na+/K+-ATPase (pump)
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15
Q

The velocity of conduction of the excitatory action potential along cardiac muscle cells is very ___ (Fast or slow)

A

FAST

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16
Q

Inside the muscle cell, calcium binds to ___ exposing myosin-binding sites to prepare for crossbridge cycle

A

Troponin

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17
Q

The calcium release channels in cardiac muscle fibers are known as ____ receptors

A

Ryanodine

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18
Q

The T tubules of cardiac muscle have a diameter __ times that of the T tubules in skeletal muscle

A

5x

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19
Q

The strength of a cardiac muscle contraction depends greatly on the concentration of ____ ions in the extracellular fluid

A

Calcium

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20
Q

In cardiac muscle, the conductance to K+ at rest is ___ and the conductance to Na+ is ____

A

High, low

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21
Q

The 3 subtypes of voltage-gated potassium channels we discussed are:

A
  1. Transient outward (lto)
  2. Delayed rectifier (lKr)
  3. Inward rectifier (lir or lKI)
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22
Q

What subtype of voltage-gated potassium channels contributes to phase 1 (initial repolarization) in cardiac muscle cells?

A

Transient outward (lto)

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23
Q

What subtype of voltage-gated potassium channels contributes to phase 3 (fast repolarization) in cardiac muscle cells?

A

Delayed rectifier (lKr)

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24
Q

What subtype of voltage-gated potassium channels contributes to phase 4 (maintaining of RMP) in cardiac muscle cells?

A

Inward rectifier (lir or lKI)

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25
Q

In skeletal muscle, the action potential signals a ____ receptor on the plasma membrane, which then opens the Ryanodine receptor of the sarcoplasmic reticulum for release of Ca2+

A

Dihydropyridine

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26
Q

In cardiac muscle, the action potential reaches a ______, which allows extracellular Ca2+ to flow into the cell to bind the Ryanodine receptor on the sarcoplasmic reticulum to then release more Ca2+ from the SR

A

Voltage-gated Ca2+ channel (L-type)

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27
Q

In cardiac muscle cells, there is a cleft of roughly ___nm for the Ca2+ to cross before it can bind to the Ryanodine receptor on the SR

A

12

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28
Q

The 2 types of cardiac muscle cells

A

Contractile, conducting

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29
Q

____ cells constitute the majority of atrial and ventricular tissues, and are the WORKING cells of the heart

A

Contractile

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30
Q

____ cells function to rapidly spread action potentials over the entire myocardium

A

Conducting

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31
Q

This is known as the “pacemaker” of the heart

A

Sinoatrial node (SA)

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32
Q

Slow conduction through the ____ ensures that the ventricles have enough time to fill with blood before being activated to contract

A

AV node

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33
Q

Conduction through the _____ system is extremely fast to allow for efficient contraction and ejection of blood

A

Bundle of His-Purkinje

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34
Q

In an electrocardiogram (ECG, EKG), the P wave is reflecting what?

A

Atrial depolarization

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35
Q

In an ECG, the QRS complex is reflecting what?

A

Ventricular depolarization

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36
Q

In an ECG, the T wave is reflecting what?

A

Ventricular repolarization

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37
Q

In an ECG, S-T segment depression may suggest what?

A

Myocardial ischemia (coronary artery disease - fat/plaque buildup in coronary arteries)

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38
Q

This specialized part of the conducting system can generate action potentials spontaneously without neural input. It also has an unstable resting membrane potential

A

SA node

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39
Q

In SA nodal cells, the upstroke (phase 0) is a result of _____, rather than the fast influx of Na+ in most muscle and neural cells

A

Fast inward Ca2+ currents

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40
Q

The slow Na+ influx in SA nodal cells that “drifts” the cell to threshold potential is known as ____

A

Pacemaker potential

41
Q

Pacemaker potential, or phase 4, of the SA nodal cells is also known as ____

A

Spontaneous depolarization

42
Q

Threshold potential in an SA nodal cell is approx. ____

A

-30 to -40 mV

43
Q

The slow Na+ inflow current (spontaneous depolarization) is also known as ____

A

“Funny current” or lf

44
Q

In SA nodal cells, when the membrane potential reaches approx. -50mV ______ open, allowing the fast depolarization (upstroke) of the action potential

A

T-type Ca2+ channels (transient)

45
Q

The rate of phase 4 depolarization (in SA nodal cells) sets the ___

A

Heart rate

46
Q

At the end of phase 3 (in SA nodal cells), the membrane potential reaches it’s most negative value (approx. -60 to -65 mV). This is known as ____

A

Maximum diastolic potential

47
Q

The AV node, Bundle of His and Purkinje fibers also have the availability for automaticity, but it is not usually expressed. These are known as _____

A

Latent pacemakers

48
Q

Override suppression

A

When the SA node sets the heart rate, the latent pacemakers are suppressed

49
Q

If a latent pacemaker becomes the pacemaker of the heart it is called ____

A

Ectopic pacemaker

50
Q

____ is the capacity of myocardial cells to generate an action potential in response to inward, depolarizing current

A

Excitability

51
Q

During _____ it is impossible to evoke another action potential

A

Absolute Refractory Period

52
Q

During the _____ a stronger than usual stimulus is required to generate and action potential

A

Relative refractory period

53
Q

____ muscle cannot undergo tetanic contractions (sustained muscle contraction)

A

Cardiac

54
Q

____ in the aortic arch and carotid arteries monitor blood pressure

A

Baroreceptors

55
Q

Cardioregulatory and vasomotor centers are in the ______

A

Medulla oblongata

56
Q

The cranial nerve innervating the heart tissue is ____

A

Vagus (X) - Parasympathetic

57
Q

A ____ effect changes the heart rate and rhythm by affecting the electrical conduction system of the heart

A

Chronotropic

58
Q

A ____ chronotropic effect increases the heart rate, while a ____ decreases it

A

Positive, negative

59
Q

Activation of B1 receptors for a positive chronotropic effect is reliant on what hormone?

A

Norepinephrine

60
Q

Activation of B1 receptors promotes an increase in ____, causing faster phase 4 depolarization

A

lf, “funny current” (Na+ flow - in SA nodal cells)

61
Q

Positive Inotropic effect

A

Increased strength of muscular contraction

62
Q

An increase in cardiac contractility (positive inotropic effect) would cause a ______ in cardiac relaxation (negative lusitropic effect)

A

Decrease

63
Q

_____ chronotropic effects involve acetylcholine and muscarinic (M2) receptors in the SA node

A

Negative

64
Q

Activation of the M2 receptors in the SA node will lead to:

A

A decreased lf (funny current), which is a decreased rate of phase 4 depolarization…slower heart rate

65
Q

M2 receptors a coupled to a type of G-protein (Gk). Gk increases the conductance for _____

A

Potassium (K+)

66
Q

Increased K+ outflow would lead to ______, a more negative membrane potential and larger threshold potential

A

Hyperpolarization

67
Q

Describe the RIGHT cardiac circuit

A
  1. Deoxygenated blood is carried to the right atrium via the superior and inferior vena cava
  2. This blood is pushed into the right ventricle through the TRICUSPID valve
  3. Blood is pushed through the pulmonary semilunar valve
  4. Blood travels to the lungs through the pulmonary arteries
68
Q

Describe the LEFT cardiac circuit

A
  1. Oxygenated blood is brought from the lungs to the left atrium via the pulmonary veins
  2. Blood is pushed into left ventricle via the MITRAL (Bicuspid) valve
  3. Blood is pumped through the aortic semilunar valve
  4. Blood is carried to branches/tissues via the aorta
69
Q

The volume of blood pumped from the left ventricle per beat

A

Stroke volume

70
Q

Stroke volume is determined by three factors:

A
  1. Preload
  2. Afterload
  3. Contractility
71
Q

____ is the end-diastolic volume created by venous return

A

Ventricular preload

72
Q

____ is the sum of factors that oppose ejection of blood during systole

A

Ventricular afterload

73
Q

______ is the intrinsic vigor of muscle contraction related to the biochemical state of the cell

A

Contractility

74
Q

The stroke volume of the heart increases in response to an increase in the volume of blood filling the heart (the end-diastolic volume) when all other factors remain the same. What’s this called?

A

Frank-Starling mechanism

75
Q

The major component of afterload is the resistance to _____ created by the circulation

A

Blood flow

76
Q

The sympathetic nervous system _____ the heart rate and ____ the threshold potential

A

Increases, decreases (norepinephrine, B1 receptors)

77
Q

The parasympathetic nervous system ____ the heart rate and ____ the threshold potential

A

Decreases, increases (acetylcholine, M2 receptors)

78
Q

When the heart rate increases the tension of each beat increases in a stepwise fashion until it reaches a maximum value

A

Positive staircase effect

79
Q

Cardiac glycosides are ____ inotropic agents

A

Positive

80
Q

What effect do cardiac glycosides have on the Na+/K+ pump?

A

Inhibition - leads to less sodium exiting the cell, so less sodium entering the cell for the Ca2+/Na+ exchanger, more intracellular Ca2+ remains

81
Q

Describe the length-tension relationship

A

Basically, if there is an increase in end-diastolic volume (more blood) there will be an increase in tension and length on the muscle cells

82
Q

An increased preload would cause the stroke volume to _____

A

Increase

83
Q

An increased afterload would cause the stroke volume to _____ and the end-systolic volume to ______

A

Decrease, increase

84
Q

Increased contractility would cause the stroke volume to _____ and the end-systolic volume to _____

A

Increase, decrease

85
Q

The two types of cardiac minute work are:

A
  1. Volume work (cardiac output)

2. Pressure work (aortic pressure)

86
Q

Which type of cardiac minute work is more costly in terms of O2 consumption?

A

Pressure work (aortic pressure)

87
Q

Aortic stenosis would cause the left ventricle to have to generate _____ (higher/lower) pressures

A

Higher

88
Q

The point at which you can hear the 1st heart sound (“Lubb”) is _____

A

Isovolumetric ventricular contraction (ventricles contract, but valves are closed so no blood is released yet)

89
Q

The point at which you hear the 2nd heart sound (“Dubb”) is _____

A

Isovolumetric ventricular relaxation (ventricles relax, pressure falls, aortic semilunar valve closes)

90
Q

The principles that govern blood flow in the cardiovascular system

A

Hemodynamics

91
Q

The highest velocity of blood flow should be in the ____, and the lowest in the ____

A

Aorta, arterioles/capillaries

92
Q

The resistance of the entire systemic vasculature is called ____

A

Total peripheral resistance

93
Q

_____ is accomplished by vasodilation and vasoconstriction in the arterioles

A

Flow regulation

94
Q

The factors that determine the resistance of a blood vessel to blood flow are expressed by the _____ equation

A

Poiseuille

95
Q

The two types of blood flow in vessels:

A
  1. Laminar

2. Turbulent

96
Q

In laminar blood flow, the flow in the middle of the vessel is _____, while the flow next to the vessel wall is ____

A

Highest, lowest (zero)

97
Q

Turbulence increases the ____ required to drive blood flow

A

Energy

98
Q

Capacitance, or compliance, of ____ are highest, while ____ are lowest

A

Veins, arteries (aging, specifically)

Physiology (10 decks)

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