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Systems Physiology > Control of Blood Flow w/ Neural Regulation and Action Potential > Flashcards

Control of Blood Flow w/ Neural Regulation and Action Potential Flashcards

1
Q

In a graph comparing cardiac output and venous return to right atrial pressure, how do you find cardiac output/ venous return?

A

It’s at the intersection of the lines, straight over to the y axis.

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2
Q

In a graph comparing cardiac output and venous return, how do you find the mean systemic filling pressure?

A

It’s at the x-axis at value of intersection

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3
Q

What is the normal plateau level of a cardiac function curve?

A

13 L/min

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4
Q

What decreases the plateau level of a cardiac function curve?

A

Cardiac failure

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5
Q

What increases the plateau level of a cardiac function curve?

A

Sympathetic stimulation

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6
Q

What percentage of total cardiac output goes to the heart itself?

A

5%

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7
Q

What increases local blood flow?

A

Increased adenosine or decreased oxygen

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8
Q

Which is the most potent vasodilator?

A

Adenosine

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9
Q

What kind of heart has the best blood supply?

A

A well-conditioned one

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9
Q

Why does the heart have the best blood supply when well conditioned?

A

Local control of blood flow is more important than the autonomic nervous system

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10
Q

What effect does exercise have on the coronary system?

A

Dilates it

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11
Q

Why does exercise dilate the coronary system?

A

Increased adenosine

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12
Q

When will the excitation signal from the sinus node arrive at the AV node?

A

.03 seconds

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13
Q

When will the signal from the AV node leave and arrive at the AV septa (beginning of bundle of his)?

A

.12 seconds

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14
Q

The sinoatrial node had a sinus rhythm of:

A

60-80 beats/min

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15
Q

The Atrioventricular node has a rhythm of:

A

40-60 beats/min

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16
Q

Purkinje fibers have a nodal rhythm of:

A

15-40 beats/min

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17
Q

Where does heart conduction start?

A

SA node

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18
Q

Where does conduction travel through from the SA node?

A

Internodal pathway

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19
Q

From the SA node, where will the conduction pause next?

A

AV node

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20
Q

Where is the AV bundle of His located?

A

Atrial ventricular septum

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21
Q

Where does conduction arrive after bundle of His?

A

Bundle branches

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22
Q

Where are the bundle branches?

A

Interventricular septum

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23
Q

Where does conduction travel from the interventricular septum?

A

Purkinje fibers

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24
Q

Where do Purkinje fibers begin and run?

A

Begin in apex of heart and run back up to the base of the heart

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25
Q

What time does conduction end in the left heart?

A

.22 seconds

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26
Q

What time does conduction end in the right heart?

A

.21 seconds

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27
Q

Where are the SA and AV nodes and internodal pathways located?

A

Posterior wall of right atrium

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28
Q

At what point is the conduction rate the slowest?

A

Between the AV node and the AV bundle of His

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29
Q

Can heart conduction go backwards?

A

No

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30
Q

What are the excitatory components of the heart?

A

SA node, AV node, purkinje fibers

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31
Q

Which excitatory component of the heart discharges at the fastest rate?

A

SA node

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32
Q

Which excitatory component of the heart has the highest rate of conductance?

A

Purkinje fibers

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33
Q

Which excitatory component of the heart is responsible for sinus rhythm/ is the “pacemaker” of the heart?

A

SA node

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34
Q

What has the slowest rate of conduction of the cardiac action potential?

A

AV bundle of His

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35
Q

What is responsible for the drifting resting membrane potential in the nodes?

A

Leaky sodium channels

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36
Q

What happens in the nodes when threshold is reached?

A

Slow calcium channels open (in)

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37
Q

What causes the beginning of repolarization in the nodes?

A

Potassium channels open more (out)

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38
Q

What is the threshold for SA discharge?

A

-40mv

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39
Q

What is resting membrane potential of the heart?

A

-55 to -40 mV

40
Q

What does an ECG show?

A

The sum of action potentials in many cardiac cells

41
Q

What does the PR interval represent?

A

Atrial depolarization followed by atrial contraction

42
Q

What does the QT interval represent?

A

Ventricular depolarization followed by contraction

43
Q

What does the T wave represent?

A

Ventricular repolarization

44
Q

Why is atrial repolarization not seen on an ECG?

A

It is hidden by ventricular depolarization

45
Q

What does the RR interval represent?

A

Heart rate

46
Q

What is the equation for determining heart rate? How do you find X?

A

60sec/min divided by X seconds/beat
X is the boxes counted between Rs and multiplied by .04

47
Q

Describe the leads, locations, and charges of Einthoven’s Triangle

A

Right wrist, negative charge has lead 1 to left wrist, positive charge
Right wrist, negative charge has lead 2 to left ankle, positive charge
Left wrist, negative charge has lead 3 to left ankle, positive charge

48
Q

What law describes the intrinsic regulation of the heart?

A

Frank-Starling’s law

49
Q

What is Frank-Starling’s law?

A

Venous return = cardiac output (what goes in must come out)

50
Q

What is responsible for extrinsic regulation of the heart?

A

Autonomic nervous system

51
Q

What does increased sympathetics to the heart cause?

A

Increased heart rate and increased stroke volume

52
Q

What is the mechanism of sympathetics to the heart?

A

Increased Na/Ca coming in increases conduction velocity (depolarizing nodes)

53
Q

What is the origin of sympathetics to the heart?

A

T2-T4

54
Q

What sympathetic neurotransmitter is released in the heart and what receptors respond?

A

Norepinephrine is the neurotransmitter
Beta 1 adrenergic receptors respond

55
Q

How do sympathetics increase heart rate?

A

Increasing the rate of SA/AV node firing

56
Q

How do sympathetics increase stroke volume?

A

Stimulating cardiac myocytes which increases contractility

57
Q

When sympathetics increase stroke volume, what is the result?

A

Increased EDV and decreased ESV

58
Q

What does decreased sympathetics cause in the heart?

A

Decreases heart rate and stroke volume

59
Q

What effect do parasympathetics have on the heart?

A

Decreases heart rate

60
Q

What is the mechanism of parasympathetics in the heart?

A

Hyperpolarizes nodes by increased K out

61
Q

What is the origin of parasympathetics to the heart?

A

Vagus nerve

62
Q

What parasympathetic neurotransmitter is released on the heart and what receptors respond?

A

Acetylcholine is the neurotransmitter
Muscarininc receptors respond

63
Q

Why don’t parasympathetics decrease contractility?

A

They do not go to cardiac myocytes

64
Q

What has the most impact on cardiac output?

A

Sympathetics

65
Q

Name 6 metabolic vasodilators

A
  1. adenosine
  2. AMP, ADP
  3. CO2
  4. H+
  5. K+
  6. lactic acid
66
Q

Name six “other” vasodilators

A
  1. NO
  2. bradykinin
  3. substance P
  4. histamine
  5. leukotrienes
  6. lack of oxygen
67
Q

Name six vasoconstrictors

A
  1. serotonin
  2. norepinephrine
  3. epinephrine
  4. angiotensin II
  5. vasopressin (ADH)
  6. endothelin
68
Q

Blood flow is proportional to…

A

blood pressure

69
Q

What is active hyperemia?

A

Increase in blood flow and pressure, brings more nutrients and oxygen into the tissue

70
Q

What is reactive hyperemia?

A

Increase in blood flow and pressure, brings an increase in oxygen to the tissues, which causes a rebound vasoconstriction back to normal size.

71
Q

Describe autoregulation theory of blood vessels

A

Blood vessels react to the vessel’s size, constricting if too large and dilating if too small

72
Q

How much of blood volume is in the systemic circulation? How much is in the systemic veins?

A

84% in systemic circulation
64% in the systemic veins

73
Q

How much of blood volume is in the cardio-pulmonary system?

A

16%

74
Q

___ have the largest compliance

A

Veins

75
Q

Venous return is determined by what three factors?

A
  1. skeletal muscle pump
  2. respiratory pump
  3. sympathetic nervous system
76
Q

Backflow in veins is prevented by ___. Problems with this leads to ___.

A

prevented by valves
problems lead to varicose veins

77
Q

Central venous pressure=

A

right atrial pressure (0 - +4 mmHG)

78
Q

Mean arterial pressure=

A

2/3 diastolic pressure + 1/3 systolic pressure

79
Q

Pulse pressure=

A

Systolic pressure - diastolic pressure

80
Q

The factors that increase systolic/pulse pressure:

A
  • increased SV
  • increased heart rate
  • decreased aorta compliance
81
Q

What are Korotkoff sounds?

A

Sounds heard when blood pressure is measured with a cuff

82
Q

What effect does high blood pressure have on baroreceptors?

A

Increases the rate of firing

83
Q

Increased rate of firing of baroreceptors causes what?

A

The vasomotor center (vasoconstrictor area) turns off which decreases sympathetic nervous system

84
Q

As vasomotor center turns off, decreasing sympathetic nervous system, what happens to blood pressure? What happens to heart rate? What happens to cardiac output?

A

Blood pressure decreases to normal by increasing vagus to heart to decrease the heart rate and force of contraction, thereby decreasing cardiac output.

85
Q

Where are baroreceptors located?

A

Carotid sinus and aortic arch

86
Q

Chemoreceptors connect ___ to ___

A

breathing to heart rate

87
Q

Where are chemoreceptors?

A

Carotid bodies

88
Q

What do chemoreceptors respond to? What is the result of their response?

A

Respond to decreased oxygen or increased CO2, which increases breathing rate and turns on sympathetic nervous system

89
Q

Name the circulation reflexes

A
  • orthostatic hypotension
  • bainbridge
  • CNS ischemic response
  • cushing reaction
90
Q

Describe orthostatic hypotension

A

From supine/sitting position to standing up, gravity causes blood pressure to drop to feet, decreasing blood to baroreceptors

91
Q

What is the effect of orthostatic hypotension?

A

Increase in sympathetic stimulation

92
Q

Describe bainbridge circulation reflex

A

To prevent damming of blood in veins, increases heart rate in response to increased blood pressure

93
Q

What is the effect of bainbridge circulation reflex?

A

Increased blood pressure leads to increase in heart rate

94
Q

Describe CNS ischemic response

A

When BP is <60 or there is lack of oxygen or blood to the brain, there is a last ditch effort to get more blood to the brain

95
Q

What is the effect of CNS ischemic response?

A

Mass sympathetic discharge to increase BP to brain leads to organ failure

96
Q

Describe cushing reaction

A

If CSF pressure is greater than BP to brain and causes the collapse of blood vessels leading to a CNS ischemic response

97
Q

What is the effect of cushing reaction?

A

Mass sympathetic discharge to increase BP to brain leads to organ failure due to high CSF pressure (special type of CNS ischemic response)

Systems Physiology (11 decks)

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