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314 Exam 2 > The Physiology of Circulation > Flashcards

The Physiology of Circulation Flashcards

1
Q

pumping action of the heart causes

A

blood flow

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2
Q

blood flow is measured as the

A

amount of blood traveling through any organ, tissue, or blood vessel in a given period of time (mL/minute)

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3
Q

velocity of blood flow depends on

A

cross sectional area through which it flows

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4
Q

blood perfusion describes

A

the flow of blood through a given volume or mass of tissue per unit of time

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5
Q

the total blood flow in a resting individual is

A

constant and equal to his or her cardiac output, but blood flow through any particular organ varies from minute to minute as blood gets redirected through different organ systems

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6
Q

hemodynamics are based on

A

blood pressure and resistance

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7
Q

blood flow is directly proportional to the

A

difference in pressure between two points

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8
Q

blood flow is inversely proportional to the

A

resistance it encounters

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9
Q

blood pressure is

A

the force exerted by blood against the walls of a blood vessel when it encounters resistance as it flows

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10
Q

blood pressure is determined by

A

cardiac output, blood volume, and resistance

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11
Q

cardiac output is the product of

A

stroke volume and heart rate

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12
Q

systolic blood pressure occurs during

A

ventricular contraction

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13
Q

diastolic blood pressure occurs during

A

ventricular relaxation

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14
Q

pulse pressure is

A

the difference between the systolic blood pressure and the diastolic blood pressure

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15
Q

mean arterial blood pressure propels blood to

A

the tissues and measures the stress on blood vessels based upon diastolic pressure and pulse pressure

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16
Q

peripheral resistance describes

A

the opposition to blood flow because of friction between blood and the walls of the blood vessels

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17
Q

resistance is directly proportional to

A

blood viscosity

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18
Q

blood viscosity depends on

A

ratio of erythrocytes to plasma volume and concentration of proteins in blood plasma

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19
Q

any reduction in number of erythrocytes

A

reduces viscosity, so it decreases resistance

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20
Q

any reduction in concentration of plasma proteins

A

reduces viscosity, so it decreases resistance

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21
Q

any increase in number of erythrocytes

A

increases viscosity, so it increases resistance

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22
Q

dehydration increases

A

blood viscosity, so it increases resistance

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23
Q

resistance is directly proportional to

A

vessel length

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24
Q

longer blood vessels provide more

A

friction and greater peripheral resistance

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25
Q

adjusting ____________ has the greatest short term influence on blood flow

A

BLOOD VESSEL RADIUS

because viscosity is relatively stable and vessel length does not change over short periods of time

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26
Q

vasoconstriction

A

reduces radius of blood vessel

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27
Q

vasodilation

A

increases radius of a blood vessel

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28
Q

resistance is inversely proportional to

A

vessel radius

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29
Q

blood typically exhibits laminar flow by moving

A

faster near center of a blood vessel due to less friction, and slower near walls of blood vessel due to more friction

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30
Q

decreasing radius of a blood vessel by half increases resistance by

A

16 times

31
Q

because of differences in cross-sectional areas

A

blood flow declines from arteries to capillaries, but increases from capillaries to veins

32
Q

autoregulation describes

A

ability of an organ to regulate its own blood supply by varying the resistance of the arterioles in order to meet the metabolic demands for oxygen, nutrients, and waste removal

33
Q

warming promotes

A

vasodilation

34
Q

cooling promotes

A

vasoconstriction

35
Q

vasoactive chemicals by platelets, leukocytes, or endothelial cells alter

A

blood vessel radius

36
Q

lactic acid, histamines, and nitric oxide are examples of

A

vasodilators

37
Q

the cardiovascular center in the medulla oblongata contains a

A

cardiac center and a vasomotor center, which exerts neural control over blood vessels by transmitting impulses to maintain vasomotor tone

38
Q

vasomotor tone describes

A

a state of moderate constriction that varies from organ to organ

39
Q

baroreflexes are

A

negative feedback responses to changes in blood pressure that get detected by receptors in aorta and carotid arteries

40
Q

increase in blood pressure stimulates

A

baroreflexes, to send signals to vasomotor center to reduce vasomotor tone and cause vasodilation

41
Q

decrease in blood pressure promotes

A

vasoconstriction

42
Q

baroreflexes correct momentary drops in

A

blood pressure

43
Q

chemoreflexes are

A

autonomic responses to changes in pH, oxygen concentration, or carbon dioxide concentration defected by aortic bodies and/or carotid bodies

44
Q

acidosis, hypoxia, or hypercapnia stimulate

A

chemoreceptors to cause widespread vasoconstriction to increase blood pressure

45
Q

hormones influence

A

blood pressure

46
Q

angiotensin II is a

A

vasoconstrictor that raises blood pressure when kidney perfusion is inadequate

47
Q

angiotensin converting enzyme (ACE) can be

A

blocked by drugs to reduce angiotensin II levels, which reduces BP

48
Q

aldosterone promotes

A

the retention of sodium ions, which promotes water retention and raises BP

49
Q

antidiuretic hormone (vasopressin) is a

A

vasoconstrictor released from posterior lobe of pituitary gland, which causes kidneys to conserve water and raise BP

50
Q

epinephrine and norepinephrine are

A

vasoconstrictors that raise BP

-they bind to adrenergic receptors on smooth muscle to stimulate contractions

51
Q

capillary exchange describes

A

the movement of substances into and out of capillaries

52
Q

diffusion is

A

an important exchange mechanism used to move glucose and oxygen between the blood and tissues and to move wastes and carbon dioxide between the tissues and blood

53
Q

transcytosis occurs when

A

endothelial cells transport fluid-filled vesicles that contain albumin, fatty acids, or insulin across capillaries

54
Q

bulk flow is a

A

passive process by which dissolved substances move from blood into the interstitial fluid by filtration, and from the interstitial fluid into the blood by reabsorption

55
Q

filtration results from

A

blood hydrostatic pressure and interstitial fluid osmotic pressure

56
Q

blood hydrostatic pressure (BHP) is generated by

A

the hearts pumping action

  • is higher at arterial end of capillary bed than at venous end
  • because of solutes present in interstitial fluid
57
Q

interstitial fluid osmotic pressure (IFOP)

A

draws water out of the capillaries

58
Q

reabsorption results from

A

colloid osmotic pressure and interstitial fluid hydrostatic pressure

59
Q

blood colloid osmotic pressure (BCOP)

A

draws water into capillaries

60
Q

interstitial fluid hydrostatic pressure (IFHP)

A

is negligible

61
Q

net filtration pressure

A

NFP= (BHP + IFOP) - (BCOP + IFHP)

62
Q

BHHP is higher at

A

arterial end of capillary bed

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63
Q

BCOP is higher at

A

the venous end of capillary bed

-there is net inward pressure and fluid moves into capillary from interstitial space

64
Q

about 85% of the 20 liters of fluid filtered out of the capillaries each day gets

A

reabsorbed into blood

65
Q

remaining fluid gets absorbed by the

A

lymphatic system to prevent fluid from accumulating in tissues, which is then returned to blood

66
Q

there is a pressure gradient from the venules to the vena cavae that favors

A

blood flow back to the right atrium, even though blood pressure remains steady at 15 mm Hg and changes very little during the cardiac cycle

67
Q

gradient will increase when blood volume

A

increases or when veins dilate

68
Q

gradient will decrease when veins constrict

A

or if pressure increases in right atrium due to leaky tricuspid valve

69
Q

skeletal muscle “pumps” in limbs

A

squeeze blood out of veins toward the heart

70
Q

at rest, both valves in a venous segment are

A

open and blood flows toward heart

71
Q

muscle contraction compresses the vein which

A

forces blood through proximal valve

72
Q

muscle relaxation causes the proximal valve to

A

close and blood enters venous segment through open distal valve

73
Q

a thoracic (respiratory) pump

A

aids in blood flow toward the heart because differences in pressure during inhalation and exhalation “squeeze” in the inferior cava

74
Q

physical activity increases

A

venous return because the heart beats faster and harder, blood vessels dilate, muscle contractions increase, and respiratory rate and depth increases

314 Exam 2 (7 decks)

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