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Anatomy and Physiology II > Chapter 30 > Flashcards

Chapter 30 Flashcards

1
Q

What is hemodynamics?

A

-mechanisms that influence the changing circulation of blood to maintain the body’s internal environment

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2
Q

What must the mechanisms of hemodynamics accomplish?

A
  • maintain circulation

- vary the volume and distribution of blood circulated

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3
Q

How does blood move?

A

-from high-pressure area to low-pressure area

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4
Q

Which of Newton’s laws apply to circulation? What do they mean?

A
  • 2nd laws of motion
  • fluid does not flow when the pressure is the same throughout
  • high to low pressure
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5
Q

Where is blood pressure at its highest? Lowest?

A
  • Highest: aorta

- Lowest: superior and inferior vena cava

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6
Q

Why does blood pressure change in this direction?

A
  • flow resistance

- resistance to flow increases away from the aorta

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7
Q

Where does the biggest change in blood pressure occur?

A

-arterioles

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8
Q

What influences blood pressure?

A
  • cardiac output

- peripheral resistance

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9
Q

What is cardiac output?

A

-the amount of blood that flows out of a ventricle of the heart per unit of time

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10
Q

What is resting cardiac output?

A
  • 5000 ml per min

- 5 liters per min

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11
Q

What determines cardiac output?

A
  • stroke volume

- heart rate

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12
Q

What is stroke volume?

A

-the volume of blood pumped out by each beat

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13
Q

What influences stroke volume?

A
  • inotropic factors
  • stretch of heart
  • neural factors
  • endocrine factors
  • cardiac afterload
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14
Q

What is contractility?

A

-strength of contraction

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15
Q

What is cardiac afterload? How does it affect stroke volume?

A
  • the work required to push blood into the arteries

- reduces stroke volume

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16
Q

What normally controls heart rate?

A

-SA node

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17
Q

What does the parasympathetic nervous system do to heart rate?

A
  • decreases the heart rate

- acetylcholine

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18
Q

What does sympathetic nervous system do to heart rate?

A
  • increases the heart rate

- norepinephrine

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19
Q

What are baroreceptors?

A
  • they detect blood pressure

- detect stretch

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20
Q

What are cardiac pressoreflexes?

A

-receptors sensitive to changes in pressure

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21
Q

Where do you find the baroreceptors for cardiac pressoreflexes?

A
  • aortic baroreceptors

- carotid baroreceptors

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22
Q

How does the carotid sinus reflex work?

A
  • small dilation at the beginning of the internal carotid artery
  • detects an increase in blood pressure
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23
Q

How does the aortic reflex work?

A
  • contains baroreceptors in the wall of the aorta
  • send afferent fibers to the cardiac control center via the vagus nerve
  • detects an increase in blood pressure
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24
Q

What other factors influence heart rate?

A
  • exercise
  • emotions
  • hormones
  • blood temperature
  • pain (slows)
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25
Q

How do you calculate cardiac output?

A

-stroke volume x heart rate

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26
Q

What is peripheral resistance?

A
  • resistance to blood flow due to friction between blood and the walls of the vessels
  • partially due to viscosity and small diameter of arterioles and capillaries
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27
Q

How does an increase in peripheral resistance affect blood pressure?

A

-the more resistance, the higher the blood pressure

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28
Q

What influences peripheral resistance?

A
  • blood viscosity: increased hematocrit and protein molecules
  • diameter of capillaries and arterioles
  • vasoconstriction and vasodilation
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29
Q

What is viscosity?

A

-blood thickness

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30
Q

How does viscosity affect peripheral resistance?

A

-increase in viscosity causes increase in peripheral resistance causes increase in blood pressure

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31
Q

What is the viscosity of blood in someone who is severely anemic?

A

-lower due to the low levels of hematocrit in their blood

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32
Q

What is the vasomotor mechanism?

A
  • smooth muscle control over the diameter of vessels

- changes the amount of resistance

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33
Q

What is vasoconstriction?

A
  • reduction in vessel diameter

- 1/2 cm

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34
Q

How does vasoconstriction affect peripheral resistance?

A

-increases resistance

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35
Q

How does vasoconstriction affect the blood flow to that area?

A

-the blood flow to that area will decrease

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36
Q

What controls vasoconstriction or vasodilation?

A
  • vasomotor control mechanism

- medulla

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37
Q

What is vasodilation?

A
  • increase in vessel diameter

- 2 cm

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38
Q

How does vasodilation affect peripheral resistance?

A

-decreases resistance

39
Q

How does vasodilation affect the blood flow to that area?

A

-the blood flow to that area will increase

40
Q

What are blood reservoirs?

A
  • venous networks and sinuses in the skin and abdominal organs (liver and spleen)
  • NOT in skeletal muscle, heart, or brain
41
Q

What is the importance of blood reservoirs?

A

-serves as a slowly moving reserve of blood

42
Q

What activates the vasomotor mechanism?

A
  • change in blood pressure (vasomotor pressoreflexes)

- blood’s oxygen or carbon dioxide content (vasomotor chemoreflexes)

43
Q

Where are vasomotor pressoreflexes found?

A

-in the internal carotid and aorta

44
Q

What do vasomotor pressoreflexes detect?

A

-sends information about blood pressure to the medulla

45
Q

What happens if vasomotor pressoreflexes detect high/low blood pressure?

A
  • high bp = inhibition of sympathetic fibers = vasodilation

- low bp = more sympathetic fibers = vasoconstriction

46
Q

Where are vasomotor chemoreflexes found?

A

-located in the aortic and carotid bodies

47
Q

What are vasomotor chemoreflexes most sensitive to?

A
  • hypercapnia

- excess of carbon dioxide in the blood

48
Q

What is it called when there is a decrease of oxygen in the blood?

A

-hypoxia

49
Q

What affect will these vasomotor chemoreflexes have if they detect hypercapnia?

A
  • constrict reservoir vessels
  • increase heart rate
  • increase stroke volume
50
Q

What is the medullary ischemic reflex?

A

-when blood flow to the brain drops below normal

51
Q

What can manipulate the vasomotor centers in the medulla?

A
  • cerebral cortex
  • hypothalamus
  • in response to fear or anger
52
Q

What is venous return?

A

-the amount of blood returned to the heart by veins

53
Q

What influences venous return?

A
  • reservoir function of veins
  • blood pressure
  • gravity
54
Q

What is the orthostatic effect?

A

-when blood remains in the veins of limbs due to too low of a blood pressure

55
Q

What are venous pumps?

A

-promotes the return of venous blood

56
Q

What mechanisms work as a venous pump?

A
  • respiration

- skeletal muscle contractions

57
Q

How do respirations work as a venous pump?

A
  • each time the diaphragm contracts, the thoracic cavity becomes larger
  • pressure alternates between the abdominal and thoracic cavity
58
Q

How do skeletal muscle contractions work as a venous pump?

A
  • as each skeletal muscle contracts, it squeezes the soft veins scattered within it
  • blood moves towards the heart
59
Q

What is total blood volume?

A
  • the total amount of blood flowing through the body

- affected by the amount of water in your blood and osmolarity

60
Q

What is capillary exchange?

A

-the exchange of materials between plasma in the capillaries and surrounding interstitial fluid of systemic tissues

61
Q

What influences capillary exchange?

A
  • osmotic pressure

- hydrostatic pressure

62
Q

What is hydrostatic pressure?

A

-the pressure the blood exerts against a blood vessel wall

63
Q

How does hydrostatic pressure in arteries differ than that in veins? How does this affect capillary exchange?

A
  • arteries have a really high blood pressure = high hydrostatic pressure
  • veins have a lower blood pressure = low hydrostatic pressure but high osmotic pressure
  • loses water but everything else stays; reabsorbs at end of the capillary
64
Q

What is osmotic pressure?

A
  • the concentration of solutes in one solution vs another solution that doesn’t
  • causes water to want to move to the highly concentrated area
65
Q

How does osmotic pressure in arteries differ than that in veins?

A
  • arteries have a low osmotic pressure

- veins have a high osmotic pressure

66
Q

What hormones influence changes in blood volume?

A
  • antidiuretic hormone
  • renin-angiotension-aldosterone system
  • atrial natriuretic hormone
67
Q

How does ADH affect blood volume?

A
  • released by the posterior pituitary gland
  • controls water movement
  • increases water absorbed = increases blood pressure
68
Q

How does the RAAS affect blood volume?

A
  • kidney detects low bp and secretes renin
  • renin circulates and causes angiotensinogen to become angiotensin 1
  • angiotensin 1 circulates to lungs
  • angiotensin-converting enzyme (ACE) converts AG1 to AG2
  • angiotensin 2 causes vasoconstriction (causes increase in bp) and causes adrenal cortex to secrete aldosterone
  • aldosterone causes reabsorption of sodium in kidneys (causes increase in osmotic pressure so water is also reabsorbed)
69
Q

How does ANH affect blood volume?

A
  • secreted by the atria of the heart
  • lowers bp
  • causes sodium loss which lowers osmotic pressure which lowers blood volume
70
Q

How do you measure blood pressure?

A
  • sphygmomanometer

- measures arterial bp

71
Q

What does the first sound mean? Second?

A
  • first: heart at work (systole); amount of ventricular contraction
  • second: heart at rest (diastole); resistance of blood vessels
72
Q

What are korotkoff sounds?

A

-the sounds that you hear while listening to bp

73
Q

What is a normal blood pressure reading?

A

-120/80

74
Q

What is hypertension?

A

-high blood pressure

75
Q

What is hypotension?

A

-low blood pressure

76
Q

What is mean arterial pressure?

A

-average blood pressure in arteries

77
Q

How do you calculate mean arterial pressure?

A

-[(2 x diastolic pressure) + systolic pressure] / 3

78
Q

What is a normal mean arterial pressure?

A

-70mm - 110mm

79
Q

What is an abnormal mean arterial pressure? What could this mean?

A
  • below 70

- hypotension; blood isn’t circulating throughout the entire body

80
Q

How does blood bleed differently in arteries, veins, and capillaries?

A
  • gushing in arteries
  • pooling in veins
  • dripping in capillaries
81
Q

What is velocity of blood flow?

A

-the rate at which blood flows in different parts of the blood vessels

82
Q

What does velocity of blood depend on?

A

-the speed of blood flow depends on the cross-sectional size of one area compared to another

83
Q

How does velocity of blood change from arteries to arterioles to capillaries to venules to veins?

A
  • fast in arteries, slow in arterioles
  • slower in capillaries than in arterioles
  • venules flow faster than capillaries
  • veins flow slower than venules
84
Q

Where is blood flowing the fastest? Slowest?

A
  • fastest: aorta or arteries

- slowest: capillaries

85
Q

What is pulse?

A

-the alternate expansion and recoil of an artery

86
Q

What causes you to feel pulse?

A
  • intermittent injections of blood from the heart to the aorta
  • elasticity of arterial walls
87
Q

What is being represented by the expansion of the arterial wall?

A

-when ventricle contracts

88
Q

What is being represented by the recoil of the arterial wall?

A

-when ventricle relaxes

89
Q

What is a pulse wave?

A

-ventricular systole starts a new pulse which proceeds as a wave of expansion

90
Q

The __________ from the heart, the ________ the interval between systole and feeling a pulse.

A
  • farther

- longer

91
Q

How does the elasticity of arteries affect circulation?

A
  • conserves energy
  • gives the arteries potential energy
  • recoil will exert pressure on the blood to keep it moving
92
Q

What are the common sites for finding a pulse?

A
  • radial
  • temporal
  • common carotid
  • facial
  • brachial
  • femoral
  • popliteal
  • posterior tibial
  • dorsalis pedis
93
Q

What are common sites for applying pressure to stop bleeding?

A
  • temporal
  • facial
  • common carotid
  • subclavian
  • brachial
  • femoral

Anatomy and Physiology II (19 decks)

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