Physiology Quiz 6 (Cardiovascular) Flashcards Preview

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Flashcards in Physiology Quiz 6 (Cardiovascular) Deck (102):
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Automaticity

Ability to fire action potential with no outside influence acting upon it (all heart structures have this property)

1

Ectopic center

Area of cardiac muscle which normally does not perform pacemaker function that suddenly takes up pacemaker function
Common source of arrhythmia

2

Causes of ectopic center

-Localized ionic imbalance
-high level of vagal tone to heart
-ischemia to area of the heart

3

Vasovagal response

Sudden increase in parasympathetic tone to heart (Ach), often caused by sudden, intense emotional shock; causes syncope

4

Ischemia

Decreased blood flow

5

Hypoxia

Decreased oxygen

6

How Ach acts on heart

Decreases HR
Decreases inotropic state

7

Hemodynamics

Application of physics to blood flow in the cardiovascular system

8

Equation for blood flow to an area

Q=P/R
Q= flow
P= pressure (mmHg)
R= resistance to blood flow

9

Resistance to blood flow equation

R= 8(nu)(length of pathway)/pi(radius to the 4th power)

10

Poiseuille's law

Q=P(radius to 4th power)(Pi)/8(nu)L

11

Pascals law

Relates the effects of gravity on perfusion of blood to regions as well as development of edema

12

Starling-landis relationship

(Graph with hydrostatic pressure and oncotic pressure lines criss-crossing)
Relates oncotic and hydrostatic pressures along capillary length

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Hydrostatic pressure drops the entire length due to...

Resistance to flow in capillary

14

Cause of current sink

Area becomes hypoxic
Charge approaches 0
-not producing ATP
-decreased energy for sodium potassium pump
-sodium leaks in and pump does not pump potassium out, so charge becomes more positive
Becomes current sink

15

What happens when a current sink forms?

Will start initiating spikes
Becomes new pacemaker

16

Does a current sink give a coordinated contraction ?

No

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What pathology can cause a current sink

Atherosclerosis

18

Atrial flutter

Faster than normal contraction of atria; regular pattern

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Atrial fibrillation

Aria beat irregularly and out of coordination with ventricles

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Examples of abnormal centers of pacemaker functions

Atrial fibrillation
Atrial flutter
Paroxysmal ventricular tachycardia

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What typically proceeds paroxysmal ventricular tachycardia?

Premature ventricular contraction

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Paroxysmal ventricular tachycardia

a rapid heartbeat of sudden onset and termination caused by a quick succession of discharges from an ectopic site in a ventricle

23

What happens with ventricular fibrillation

Mass, uncoordinated contraction of ventricle; no blood pumped to system
Typically fatal in about 5 min

24

Re-entry phenomenon

Causes impulse in a cardiac contractile cell to go back up toward SA node and cancels out impulse; causes SA node to lose influence

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What must you have for re-entry phenomenon to occur

Slowed conduction
Unilateral block

26

Oncotic pressure

Osmotic pressure of blood due to plasma proteins

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Hydrostatic pressure

Pressure within blood vessel due to pumping of heart

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Where hydrostatic pressure is greater than oncotic pressure, where will fluid flow?

Capillary--> tissue

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Where oncotic pressure is greater than hydrostatic, where will fluid flow?

Tissue--> capillary

30

Edema

Change in relative levels of pressure in system that cause net gain of fluid in tissue

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What increases edema

Increased hydrostatic pressure (standing, pregnancy, renal disease, congestive heart failure)
Decreased oncotic pressure(starvation, liver dysfunction)
Increased blood volume

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What will shift the hydrostatic line upward

Congestive heart failure
Renal disease
Pregnancy

33

What will shift the oncotic pressure line downward?

Chronic starvation
Liver dysfunction

34

How much atrial pressure provides adequate perfusion for brain?

80-100 mmHg

35

Venous return

Blood returned to heart

36

Venous system is responsible for

Returning blood to heart

37

Qualities of venous system that help maintain venous return

Skeletal muscle pump
Venous valves
Thoracoabdominal pump

38

Skeletal muscle pump

Mechanism by which blood is forced back toward the heart when skeletal muscle contracts

39

Venous valves

One way valves that permit flow only in one direction

40

Vericose veins

When valves are damaged, blood is allowed to flow back to muscle
-happens in pregnancy
Eg. Hemoroids

41

Toracoabdominal pump

Blood is pulled to the heart by negative pressure in chest caused by breathing
Positive pressure in abdomen pushes blood toward thoracic cavity
-most influential during exercise

42

Factors to consider for how BP in CV system is regulated/influenced

Cardiac output
Total peripheral resistance (diameter)
Distensibility of vessels- influences, but will not control BP
Viscosity of blood-influences, but will not control BP
Blood volume available

43

Factors that act rapidly

Cardiac output
Total peripheral resistance

44

Factors that are slow acting

Changes in blood volume

45

Cardiac output

Amount of blood propelled by heart into systemic circulation per minute

46

Total peripheral resistance

Resistance to blood flow into systemic circulation

47

Blood volume

Total volume of blood in cardiovascular system

48

What are blood volume changes mediated by

Hormones

49

What % of body weight is blood?

6%
Better conditioned athletes, pregnancy ^ BV

50

Cardiac output and total peripheral resistance are changed by altering...

Neural activity

51

Cardiac output equation

CO=SV x HR

SV= stroke volume

52

Stroke volume

mL of blood propelled with each ventricular contraction (dependent on body size)

53

Ejection fraction

% of total volume in ventricle that is expelled in one beat
(Usually 60-67% @ rest)
Increases with exercise due to increased inotropic force

54

Increased papasympathetic tone to heart causes...

Decreased HR
Decreased inotropic state

55

Increased sympathetic tone to heart causes...

Increased HR
Increased inotropic state

56

Autonomic influence on the heart is determined by

Hypothalamus

57

Arterial pressure equation

AP= CO x TPR
(Want to act upon TPR to change AP; mostly controlled by radius of vessels)

58

Total peripheral resistance is under exclusive control of what autonomic system?

Sympathetic

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Control of TPR occurs primarily at the level of the_____ and is mediated by ______

Arteriole; vascular smooth muscle

60

Only places arteriolar vascular smooth muscle is innervated by parasympathetics are

Salivary glands
External genitalia

61

Local control of TPR is exerted by

Metabolic byproducts
K, H, lactic acid

62

Intrinsic control predominates over these systems

Muscle
Heart

63

Extrinsic control predominates over these systems

GI
Skin
Kidneys

64

Blood flow received by an area is a result of what system?

Balance between local and extrinsic control

65

Local/intrinsic control

Metabolic byproducts

66

Extrinsic control

Autonomic nervous system

67

When is skin a priority for circulation

In hot weather (because it is a thermoregulator)

68

How much cardiac output does the average person have at est

5-6 L/min

69

What type of control will exercising muscle be under during exercise?

Intrinsic
Will be given priority over several other circulations

70

Kidneys receive ___% of cardiac output at rest

25

71

Why do kidneys receive so much cardiac output?

Needs BF for filtering
Essential for controlling
-pH
-ionic levels
-fluid balance

72

What control will non-exercising muscle be primarily under when exercising?

Extrinsic

73

Decreased tone to smooth muscle causes

Dilation

74

Increased tone to smooth muscle causes

Constriction

75

Kidney primarily under______control at all times

Extrinsic

76

Arterial barorecepors

Pressure receptors that monitor average level of arterial pressure and its rate of change

77

Where are arterial baroreceptors located?

Carotid sinus
Aortic arch

78

Where does info from aortic baroreceptors go?

Nucleus tractus solitarius in medulla

79

What does nucleus tractus solitarius do with info from arterial baroreceptors?

Compares it to set point for atrial pressure
If measured pressure is different from set point, hypothalamus alters autonomic outflow to bring pressure closer to set point

80

Arterial baroreceptors are (slow/fast) control

Fast

81

Left atrial receptors

Mechanoreceptors that monitor stretch of left atrial wall

82

Pressure in left atrial wall is directly proportional to

Blood volume

83

Decreased rate of firing of left atrial receptors is perceived as

Less blood volume

84

Where is info from left atrial receptors sent?

Centers like nucleus tractus solitarius in medulla and compares to normal set point for blood volume

85

If measured blood volume is different from set point....

Hypothalamus will change output of ADH (anti diuretic hormone)
- decreased blood volume will lad to increased release of ADH

86

Way does ADH do

Acts upon kidney to conserve water

87

Congestive heart failure

Left atrial exceptions are damaged, or set point changes

88

Renal sympathetic response in left atrial feedback loop is an exception to what?

Sympathetic system being divergent; this is point to point control

89

Renin-angiotensin

Hormone system entirely within kidney which has significant effect upon controlling BP, especially when arterial pressure drops
Looked at as a mechanism to protect renal blood flow, but also seems to be significant in protecting systemic arterial pressure

90

JGA stimulates release of

Renin

91

Renin

Enzyme produced by kidney
More released when kidney senses drop in arterial pressure at level of kidney

92

Angiotensinogen

Protein in blood that comes from liver

93

What does renin do

Acts upon angiotensinogen and produces angiotensin I

94

Angiotensin I

Has no physiological effects

95

What does angiotensin I do?

Converted to angiotensin II in lungs by converting enzyme

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Angiotensin II

Most potent vasoconstrictor in body, also stimulates retention of sodium in kidney

97

What happens to angiotensin II

Converted to angiotensin III by enzyme in blood plasma

98

Angiotensin III

Same effects as angiotensin II, but better at release of aldosterone

99

What does angiotensin III do

Releases aldosterone

100

Converting enzyme inhibitors

Drug class to block converting enzyme for hypertension patients

101

Hypertensive patients have..

Faulty JGA