Chapter 19 - The Cardiovascular System: Blood Vessels

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1

what are the three major types of blood vessels?

arteries, veins, capillaries

2

In the systemic circulation, arteries always carry ___________ blood and veins always carry __________ blood.

oxygenated, oxygen poor

3

In the pulmonary circulation, arteries always carry ___________ blood and veins always carry __________ blood

oxygen poor, oxygenated

4

which blood vessel type has intimate contact with tissue cells and directly serve cellular needs?

capillaries

5

tunics

"coverings" layers of the blood vessels, the walls of blood vessels have 3 tunics

6

lumen

cavity inside blood vessel, blood containing space

7

what are the three tunics of the blood vessels?

tunica intima
tunica media
tunica externa

8

innermost tunic

tunica intima, contains endothelium

9

endothelium

single layer of simple squamous cells that line the lumen of all vessels, minimizes friction as blood moves through the lumen

10

subendothelial layer

in vessels larger than 1mm diameter, layer consisting of basement membrane and loose connective tissue that supports the endothelium

11

middle tunic layer

tunica media

12

describe the tunica media

circularly arranged smooth muscle cells and sheets of elastin, activity of the smooth muscle is regulated by sympathetic vasomotor nerve fibers of the autonomic nervous system

13

vasoconstriction

narrowing of blood vessel, lumen diameter decreases as the smooth muscle of the tunica media contracts

14

vasodilation

relaxation of the smooth muscle of the blood vessel, producing dilation, lumen diameter decreases as smooth muscle relaxes

15

bulkiest layer of the arteries

tunica media

16

which layer of the blood vessels has the chief responsibility of maintaining blood pressure and circulation?

tunica media

17

outermost layer of the blood vessel wall

tunica externa (tunica adventitia)

18

describe the tunica externa

loosely woven collagen fibers that protect and reinforce the vessel, and anchor it to its surrounding structures

19

function of each layer of the blood vessel walls

tunica intima- forms a slick surface that minimizes friction as blood passes through the lumen
tunica media- maintains blood pressure and circulation by controlling the constriction and dilation of the blood vessel
tunica externa- protects the blood vessel, anchors it to its surroundings

20

vasa vasorum

nourish the most external tissues of the blood vessel wall, system of tiny blood vessels in the tunica externa of larger vessels

21

three types of arteries

elastic arteries, muscular arteries, and arterioles

22

elastic arteries

thick walled arteries near the heart (aorta and major branches) largest in diameter, conducting arteries (conduct blood from heart to medium-sized arteries), contain elastin (mostly in tunica media), inactive in vasoconstriction

23

muscular arteries

deliver blood to specific organs, distributing arteries, thickets tunica media

24

what type of artery has the thickest tunica media?

muscular arteries

25

arterioles

smallest type of artery, blood flow into capillaries determines by arteriole diameter, constriction=less blood flow, dilation=more blood flow

26

smallest type of artery

arterioles

27

capillaries

smallest type of blood vessel, contain pericytes, rbc's slip through in single file, 3 different types

28

smallest type of blood vessel

capillaries

29

pericytes

smooth muscle-like cells that stabilize the capillary wall and help control capillary permeability

30

3 different types of capillaries

continuous
fenestrated
sinusoid

31

most common type of capillary

continuous

32

fenestrated capillaries

endothelial cells pierced with small pores, much more permeable to fluids and small solutes than continuous capillaries,

33

intercellular clefts

gaps of unjoined membrane

34

sinusoid capillaries

sinusoids, highly modified, leaky capillaries found only in the liver, bone marrow, spleen, and adrenal medulla, irregular shaped lumen and are fenestrated, allow large molecules to pass between blood and surrounding tissue, incomplete basement membrane

35

stellate macrophages

found in sinusoids, remove and destroy bacteria

36

least permeable capillary

continuous

37

capillaries found in areas of active absorption and filtration (kidney, small intestine)

fenestrated

38

most permeable capillary, found in specific locations such as the liver, bone marrow, spleen, etc.

sinusoids

39

capillary beds

interweaving network, connect arterioles to venules, enable exchange of nutrients

40

venule

allows blood to return from capillary beds to veins

41

mircocirculation

flow of blood from arterioles to venules

42

how many types of vessels does a capillary bed consist of?

2

vascular shunt- short vessel that directly connects the arterioles to venules at opposite ends of the bed
true capillaries- the actual exchange vessels

43

terminal arteriole

feeds capillary beds

44

capacitance vessels or blood reservoirs: veins or arteries?

veins

45

venous valves

folds of tunica intima, most abundant in the limbs, usually absent in veins of the thoracic and abdominal cavities

46

varicose veins

twisted and dilated vein because of leaky valves

47

venous sinuses

highly specialized flattened veins with extremely thin walls composed of only endothelium, coronary sinus is an example

48

vascular anastomoses

joining of blood vessels

49

collateral channels

alternative pathways for blood

50

blood flow

volume of blood flowing through a vessel, organ, or entire circulation in a given period

51

blood pressure

the force per unit area exerted on a vessel wall by the contained blood, systemic arterial blood pressure in the largest arteries near the heart

52

pressure gradient

the different in BP within the vascular system, provides the driving force to keep blood moving from an area of high pressure to an area of low pressure

53

resistance

opposition to flow, measure of the amount of friction blood encounters as it passes through the vessels

54

peripheral resistance

most friction occurs in the peripheral (systemic) circulation, well away from the heart, so this term is commonly used

55

blood viscosity

thickness of blood

56

true of false: the longer the blood vessel, the greater the resistance

true

57

true or false: when BP increases, blood flow speeds up, and when it decreases it declines

true

58

true or false: if resistance increases, so does blood flow

false

59

F = BP/R

-

60

true or false: blood moves from higher pressure to lower pressure areas

true

61

systemic blood pressure is highest in the____

aorta

62

BP reaches 0mm Hg in the _____

right atrium

63

The steepest drop of blood pressure occurs in the ___

arterioles which offer the greatest resistance to blood flow

64

Arterial BP depends on what two factors?

how much the elastic arteries close to the heart can stretch, and the volume of blood forced into them at any time

65

True or false: if the amount of blood entering and leaving the elastic arteries in a given period were equal, arterial pressure would be constant

true

66

pulsatile

rises and falls in a regular fashion

67

systolic pressure

pressure exerted by blood on blood vessel wall during ventricular contraction

68

average systolic pressure

120 mm Hg

69

diastolic pressure

lowest level of any given cardiac cycle, arterial blood pressure reached during or as a result of diastole

70

average diastolic pressure

70-80 mm Hg

71

pulse pressure

the difference between the systolic and diastolic pressure

72

why does atherosclerosis chronically increase pulse pressure?

elastic arteries become less stretchy

73

MAP (mean arterial pressure)

the pressure that propels the blood into the tissues

74

which last longer, diastole or systole?

diastole

75

true or false: the MAP is equal to the diastolic pressure plus one third pulse pressure?

true

MAP = diastolic pressure + pulse pressure/3

76

true or false: MAP and pulse pressure increase with increasing distance from the heart

false, MAP and pulse pressure decrease with increasing distance from the heart

77

blood pressure when first reaches capillaries and when leaving capillary beds

35 mm Hg - 17 mm Hg

78

why are low capillary pressures desirable?

they are fragile and extremely permeable

79

true or false: venous blood pressure is relatively stable and unchanging

true

80

three functional adaptions critical to venous return

muscular pump
respiratory pump
sympathetic venoconstriction

81

three factors that maintain blood pressure

CO, PR, BV

82

how to BP, CO, and PR relate to each other in formulas

F = BP/PR

BP= F x PR

83

CO = ?

CO = SV x HR

84

vasomotor fibers

sympathetic nerve fibers that cause the contraction of smooth muscle in the walls of blood vessels, therefore regulation blood vessel diameter

85

vasomotor tone

state of moderate constriction

86

baroreceptors

a sensory nerve ending in the wall of the carotid sinus or the aortic arch sensitive to vessel stretching

87

when stretched, baroreceptors _____

send a stream of impulses to the cardiovascular center, decreasing blood pressure

88

three mechanisms that bring about a decrease in blood pressure

arteriol vasodilation
venodilation
decreased CO

89

rapidly responding baroreceptors protect the circulation against_____

short term changes in BP

90

chemoreceptors

sensitive to various chemicals in a solution, most prominent are carotid and aortic bodies, play a larger role in regulating respiratory rate

91

reflexes that regulate BP are located in the ____

medulla oblongata

92

two adrenal medulla hormones

epinephrine and norepinephrine

93

effect of epinephrine and norepinephrine on BP

increase BP, increase CO and promote vasoconstriction

94

When blood pressure of volume is low, kidneys release _____

renin

95

Angiotensin II affect on BP

increases BP, stimulates vasoconstriction, promoting a rise in systemic BP, also stimulates release of aldosterone and ADH, which act in long term regulation of BP by enhancing BV

96

Atrial Natriuretic peptide (ANP) affect on BP

decreases BP, reduces BV and causes vasodilation

97

Antidiuretic hormone (ADH) affect on BP

increases BP, stimulates kidneys to preserve water, not usually important in short term regulation, vasoconstriction

98

Aldosterone affect on BP

increases BP

99

long term regulation mechanisms alter ___

BV

100

true of false: increase BV = increased BP

true

101

direct renal mechanisms

alter blood volume independently of hormones

when BP or BV rises, speed of fluid filtering from the blood stream to the kidney speeds up so more of it leaves in urine therefore BV and BP fall. and BP or BV is low, water is conserved to the bloodstream so BP and BV rise

102

hormones that increase BP

epinephrine and NE, ADH, & angiotensin

103

hormones that decease BP

ANP

104

indirect renal regulation of blood volume involves what hormonal mechanism

renin-antiotensin-aldosterone mechanism

105

explain indirect renal mechanism

when BP falls, the kidneys release renin, which triggers the formation of angiotensin II. angiotensin II causes:
1) release of aldosterone, stimulation salt and water retention
2) vasoconstriction
3) release of ADH
4) thirst

106

hypertension

high BP

107

what BP would be considered hypertension?

140/90

108

prehypertension

blood levels elevated but not in hypertension range

109

prolonged hypertension is the major cause of ___

heart failure, vascular disease, renal failure, and stroke

110

what enlarges as a result of hypertension

myocardium because it has to work harder to pump

111

primary hypertension

no underlying cause, cant be cured, 90% cases
suspected causes:
heredity
diet
obesity
age
diabetes
stress
smoking

112

secondary hypertension

10% cases, due to identifiable conditions, cured by curing problem that caused it

113

hypotension

low blood pressure 90/60

114

true or false: low blood pressure is associated with long life and an old age free of cardiovascular disease

true

115

when is low blood pressure a concern?

if it leads to inadequate blood flow to tissue

116

orthostatic hypotension

temporary drop in BP from rising suddenly

117

tissue perfusion

blood flow through tissue

118

blood flow is involved in _____

delivering oxygen and nutrients to tissue cells
exchanges gases in the lungs
absorb nutrients from digestive tract
form urine in the kidneys

119

autoregulation

the local adjustment of blood flow to individual organs based on their immediate requirement