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AU17: Physiology > Cardio Physiology > Flashcards

Cardio Physiology Flashcards

1
Q

What is hematocrit?

A

Percent of blood volume that is composed of RBCs

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2
Q

If the plasma is 55% what is the hematocrit?

A

45%

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3
Q

________ carry blood away from the heart. ______ carry blood back to the heart.

A

Arteries; veins

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4
Q

What is the equation for flow?

A

Flow = Change in pressure/resistance

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5
Q

What has the biggest effect on resistance?

A

The radius of the tube.

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6
Q

What happens to resistance with more hematocrit?

A

Higher resistance

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7
Q

What are the three roles of valves?

A
  1. Provide rigidity
  2. Don’t allow back flow
  3. Electrically isolate atria from ventricles
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8
Q

How are muscle cells electrically coupled?

A

Via gap junctions

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9
Q

T/F: Cardiac muscle cells can be recruited.

A

FALSE

Each fiber contracts with each beat

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10
Q

Describe the parasympathetic innervation of the heart.

A

Vagus nerve innervates the ATRIA only. Uses ACETYLCHOLINE to activate muscarinic receptors.

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11
Q

Describe the sympathetic innervation of the heart.

A

Thoracic spinal nerves innervate the ATRIA and VENTRICLES. They release EPINEPHRINE and NOREPINEPHRINE to activate BETA receptors.

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12
Q

_________ innervation controls stroke volume and heart rate while _________ innervation only controls heart rate.

A

Sympathetic; parasympathetic

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13
Q

What is the flow of electric current through the heart?

A

SA node -> AV node -> bundle of HIS -> L and R bundles -> purkinje fibers

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14
Q

How are the nerve branches of the heart backed up in case things stop working?

A

All of the nerve fibers can spontaneously fire if the previous set of nerves don’t fire

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15
Q

What is the only method of communication between the atria and ventricles?

A

AV node

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16
Q

The electric signal goes slowly through which part of the nerve system?

A

From SA through the AV bundle

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17
Q

What is responsible for the rapid depolarization phase of myocardial muscles?

A

Rapid opening of voltage-gated Na channels

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18
Q

What causes the plateau phase of the myocardial ventricular cell contraction?

A

Calcium channels and K channels are open. Ca enters while K slowly leaves the cell.

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19
Q

What causes the repolarization of myocardial cells?

A

K rapidly leaving the cell

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20
Q

T/F: Myocardial ventricular cells have a true resting potential.

A

TRUE

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21
Q

Explain why autorhythmic cardiac nodal cells do not have a true resting potential?

A

Na ions are constantly leaking into the cell through FUNNY CHANNELS

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22
Q

Describe the process of an action potential in a nodal cell.

A

Slow entry of Na followed by slow entry of Ca -> threshold -> Ca rapidly enters (depolarization) -> K channels open and Ca close (repolarization)

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23
Q

T/F: Cells of the SA node have less funny channels than cells in the AV node.

A

FALSE

Less funny channels further down the cascade

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24
Q

What do P, QRS, and T waves represent?

A 
P = atrial depolarization
QRS = ventricular depolarization
T = ventricular repolarization
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25
Q

How does the electrical signal trigger muscle contraction?

A

Calcium channels open -> trigger calcium enters -> calcium induced calcium release -> contraction

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26
Q

Why do cardiac muscle cells have a long refractory period?

A

To allow for the ventricles to fill

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27
Q

What is the first heart sound?

A

Closure of AV valves

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28
Q

What is the second heart sound?

A

Closure of aortic and pulmonary valves

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29
Q

_________ is the narrowing of the valves. ________ is when the valves are insufficient.

A

Stenosis; regurgitation

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30
Q

Systemic and pulmonary circulations are in __________. Organs in systemic circulation are in __________.

A

Series; parallel

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31
Q

What causes the aortic valve to open?

A

Pressure in ventricle > pressure in aorta

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32
Q

When the heart is in diastole, the ventricles are _________.

A

Relaxed

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33
Q

Describe the process of the heart from diastole through systole.

A
  1. Passive filling
  2. SA node -> atrial kick
  3. Ventricles begin to contract
  4. Isovolumic contraction: both valves closed
  5. Ventricular pressure becomes greater than aortic pressure and aortic valve opens
  6. Ejection and repolarization
34
Q

T/F: The left heart creates more pressure than the right heart.

35
Q

What is cardiac output?

A

The volume of blood each ventricle pumps per minute

36
Q

What is the equation for Cardiac output?

A

CO = heart rate x stroke volume

37
Q

T/F: Parasympathetics speed up the heart rate.

A

FALSE

Slow down

38
Q

What are the two ways to increase stroke volume?

A
  1. Increase Preload/End diastolic volume: volume of blood in ventricles
  2. Increase sympathetic input
39
Q

What is the Frank-Starling mechanism?

A

The fuller the ventricles are the harder they will contract due to stretch-tension

40
Q

T/F: Increased sympathetics cause a more rapid contraction AND relaxation of myocardial cells.

41
Q

How do increased sympathetics ultimately cause greater cardiac output?

A

Increase Ca

42
Q

Is it possible to increase just one of the two possible determinants of cardiac output?

A

No. Increasing one will increase the other

43
Q

Which vessels are adjusted to regulate blood pressure?

A

Arterioles

44
Q

Does blood push through the arteries in a pulsating fashion with each heartbeat?

A

No! At systole it stretches the arteries and the recoil continues to push during diastole

45
Q

What determines organ blood flow?

46
Q

How is the intrinsic tone of arterioles controlled?

A

Local controls: active hyperemia and flow autoregulation

Extrinsic: Sympathetics

47
Q

Sympathetic stimulation of _____________ receptors causes vasoconstriction to decrease blood flow. While _____________ receptors leads to vasodilation to cause an increase in blood flow.

A

Alpha-adrenergic; beta-adrenergic

48
Q

What are some vasodilators?

A
  1. No

2. PGI2

49
Q

What is a vasoconstrictor?

A

Endothelin-1

50
Q

Increased capillary hydrostatic pressure and increased interstitial protein concentration will both lead to __________.

A

Filtration

51
Q

Increased interstitial hydrostatic pressure and increased protein concentration in the plasma will lead to __________.

A

Absorption

52
Q

At rest approx _____ of the total blood volume is in the veins.

53
Q

Alterations in venous return can alter __________, which can in turn increase stroke volume and cardiac output.

54
Q

Among all blood cells, only the _________ are true cells with nuclei.

A

Leukocytes

55
Q

What is the major breakdown product of hemoglobin?

56
Q

When an RBC is destroyed, the iron is bound by __________ and delivered to bone marrow.

A

Transferrin

57
Q

What happens when the kidneys sense low O2 levels?

A

Kidneys produce and secrete more erythropoietin -> production of RBCs in bone marrow -> more O2 carrying capacity

58
Q

Clotting can occur in the absence of all cellular elements except __________.

59
Q

Factors II, VII, IX and X are all __________ proteins.

A

Coagulation

60
Q

Proteins C and S are __________ proteins.

A

Anticoagulation

61
Q

Protein C, TFPI, and Antithrombin III all function to ________ clot formation.

62
Q

_________ mediates the process of dissolving fibrin clots.

63
Q

What is the best way to get more blood flow to a specific organ?

A

The arteries leading to the organ will decrease their resistance

64
Q

What constitutes the change in pressure through most capillary beds and in the organs?

65
Q

What is the equation for MAP?

A

MAP = cardiac output x total peripheral resistance

66
Q

What determines organ blood flow?

67
Q

Decrease in blood volume will lead to a drop in _______.

68
Q

What two factors can the body increase if there is a drop in MAP?

69
Q

What neurons function as sensors in the homeostatic maintenance of MAP?

A

Baroreceptors

70
Q

Where are baroreceptors located?

A

Aortic arch and carotid sinuses

71
Q

What will cause baroreceptors to fire more frequently?

A

An increase in MAP

72
Q

What is the result of baroreceptors firing?

A

Decreased sympathetic outflow to hear

Increased parasympathetic outflow to heart

Reduced CO

73
Q

T/F: Baroreceptors cause an autonomic response that has all its effect in the heart.

A

FALSE

Also effects arterioles and veins

74
Q

Describe the events that will lead to a stabilization of MAP after a hemorrhage.

A

Sympathetics increase to the heart, arterioles and veins

Heart: heart rate and stroke volume increase

Veins: veins constrict -> higher venous pressure and venous return -> higher EDV -> increase stroke volume

Arterioles: constrict leading to increased TPR

75
Q

Describe what happens to blood volume when MAP increases.

A

Squeezes more fluid out of blood and into the urine -> reduction in blood volume -> decrease in MAP

76
Q

During a hemorrhage, which factors instantly increase?

A

Heart rate and TPR

The rest drop abruptly before increasing

77
Q

At capillaries, reduced MAP increases ___________ and reduces ____________ to help protect blood volume.

A

Absorption; filtration

78
Q

Does plasma volume or erythrocyte volume have a more exaggerated recovery 18 hours after a hemorrhage?

A

Plasma volume

79
Q

During exercise, what happens to resistance in skeletal muscles?

A

Decreases due to vasodilation

80
Q

What factor determines maximal oxygen consumption?

A

Cardiac output

81
Q

What is the difference between diastolic and systolic dysfunction in heart failure?

A

Diastolic: reduced ventricular compliance -> lower EDV -> decreased stroke volume

Systolic: decrease in cardiac contractility -> lower stroke volume at any EDV

82
Q

What is the Frank-Starling mechanism?

A

The heart will pump harder if its filled with more blood.

To increase stroke volume increase venous return

AU17: Physiology (12 decks)

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