Chapter 19 powerpoint Flashcards


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1

Tunica intima

- Innermost layer

- Contains endothelium: runs uninterrupted through entire cardiovascular system

2

Internal, external elastic lamina

Present only in arteries

3

Tunica media

Contains smooth muscle fibers (vasoconstriction)

4

Tunica externa

Connective tissue that stabilizes blood vessels

5

Structure and function of arteries

- Need to handle larger amounts of pressure from the heart

- Have thicker walls, smaller lumens than veins

6

Elastic arteries aka:

Conducting arteries

7

Elastic arteries

- Includes aorta and its principal branches

- Have large lumens to collect large volumes of blood from the heart

8

Muscular arteries aka:

Distributing arteries

9

Muscular arteries

- Have the largest tunica media of any blood vessel type; possess a great ability to vasoconstrict

- Branch extensively to deliver blood to arterioles throughout the body

10

Arterioles

Smallest artery type

11

Largest arterioles

- Still contain all three tunics

- Resemble small muscular arteries

12

Tiniest aerterioles

Simply endothelium surrounded by 1-2 fiber layers of smooth muscle

13

___ of arterioles regulates blood flow into capillary beds

Diameter

14

Resistance vessels

Arterioles that change their diameter to allow more or less blood flow

15

Metabolic responses

Adjust blood flow based on specific demands of local tissue

- Ex: increased NO release during exercise

16

Myogenic responses

Occur reflexively within smooth muscle of tunica media

- Ex: increased pressure causes contraction

17

Capillaries

- Smallest blood vessel type, so erythrocytes flow in single file

- Site of gas and nutrient exchange: only tunic intima is present, and is permeable

18

Continuous capillaries

- Most common type

- Lining does not contain pores

- Exchange occurs through intercellular clefts and pinocytic vessels

19

Fenestrated capillaries

- Endothelial cells dotted with pores

- More readily allows passage of fluid and larger molecules

20

Sinusoid capillaries

- Have larger fenestrations and a discontinuous basement membrane

- Allow movement of entire cells through barrier

21

Organization of capillaries into capillary beds

- Precapillary sphincters

- Terminal arteriole

- Metarteriole

- True capillaries

- Thoroughfare channel

- Vascular shunt

- Postcapillary venule

22

Precapillary sphincters

Bands of smooth muscle that encircle each true capillary at its origin from a metarteriole

23

Terminal arteriole

Delivers blood to capillary bed

24

True capillaries

Vessels of exchange: branch off the metarteriole, converge upon the thoroughfare channel

25

Postcapillary venule

Drains blood away from capillary bed

26

Vascular shunt

Directly connects the terminal arteriole to the postcapillary venule

27

Thoroughfare channel

Arises from the metarteriole; returns blood to postcapillary venule

28

Metarteriole

Arises from the terminal arteriole

29

Venules

- Smallest of vessels carrying blood back to the heart

- Have all three tunics, but very thin

- Have large lumens: blood reservoirs or capacitance vessels

30

Venyles converge to form ___

Veins

31

Systemic veins- blood volume

64%

32

Systemic arteries- blood volume

13%

33

Systemic capillaries- blood volume

7%

34

Pulmonary circulation- blood volume

9%

35

Heart- blood volume

7%

36

Veins contain ___

Valves

37

Veins experience much lower pressure than ___

Arteries

38

To ensure blood returns to heart:

- Large lumens offer less resistance to blood flow

- Venous valves (specialized foldings of the tunica intima) ensure unidirectional blood flow

39

Large lumens offer ___ resistance to blood flow

Less

40

Venous valves (specialized foldings of the tunica intima) ensure ___ blood flow

Unidirectional

41

What are varicose veins?

Failure of venous valves, allowing blood to pool in peripheral veins of legs

42

Varicose veins- causes

Anything that impedes venous return (pregnancy, obesity, prolonged periods of standing)

43

Varicose veins- symptoms

Dilation and distension of veins, sometimes causing discomfort or pain

44

Blood flow (F)

Volume of blood moving through a vessel, tissue, organ or entire circulation per unit of time

45

Blood pressure (BP or P)

Force exerted onto a given area of the vessel wall by the blood contained within it, measured in mm Hg

46

Resistance (R)

Friction encountered by blood, impeding its flow

47

F =

Delta P/ R

48

Three variables influence resistance

- Blood viscosity

- Blood vessel length

- Blood vessel radius

49

Poiseuille's equation

Delta P = 8nLF/pi(r)4

50

Rearranging for F

F = pi(delta)(P)(r)4/8nL

51

Orignal equation

R = delta P/F

52

Substituting F with poiseuille's equation

R = 8nL/pi(r)4

53

Delta P

Difference in pressure between two points

54

n

Viscosity of the bluid

55

L

Length of the tube

56

F

Rate of flow

57

Pi

Mathematical constant

58

r

Radius of the tube

59

Total peripheral resistance (TPR)

- Used to describe forces impeding blood flow throughout the entire circulation

- Mainly due to veins, not arteries

60

Flow is normally ___, but abrupt changes in diameter can lead to ___ flow, increasing ___

Laminar; turbulent; resistance

61

Blood vessels exhibit ___

Compliance

- Ability to change structure in response to changes in pressure

62

Mean arterial pressure =

Diastolic blood pressure + Pulse pressure/3

63

Capillary blood pressure and exchange

- CHP

- IFHP

- BCOP

- IFCOP

64

CHP

Pressure exerted by blood onto capillary wall

65

- IFHP

- BCOP

Pressure opposing filtration

66

IFCOP

Pressure exerted by proteins in interstitial fluid

67

Net filtration pressure =

(CHP + IFCOP) - (IFHP + BCOP)

68

Pressure in veins is much ___ than arteries

Lower

69

Muscular pump assists venous return

During contraction, bulging muscles compress veins, forcing blood back towards the heart

70

Respiratory pump also assists venous return

During inspiration, intrathoracic pressure decreases, drawing blood towards the thoracic cavity

71

Blood pressure varies with ___ and ___

Cardiac output; peripheral resistance

72

MAP = CO x TPR

(1)

Increasing either cardiac output or peripheral resistance increases blood pressure

73

MAP = CO x TPR

(2)

CO = SV x HR

Increasing either stroke volume or heart rate increases cardiac output

74

Nervous control of blood pressure

Baroreceptors

75

Receptors (BP increased)

- Baroreceptors in various locations are stimulated

- More impulses sent to cardiovascular center

76

Control center (BP increased)

- Cardioinhibitory center is excited

- Cardioacceleratory and vasomotor centers are inhibited

77

Effectors (BP increased)

- Heart: HR and contractility decrease

- Blood vessels: vasodilation

- Lowered CO and R will lower BP

78

Receptors (BP decreased)

- Baroreceptors in various locations are inhibited

- Fewer impulses sent to cardiovascular center

79

Control center (BP decreased)

- Cardioacceleratory and vasomotor centers are excited

- Cardioinhibitory center is inhibited

80

Effectors (BP decreased)

- Heart: increased HR and contractility

- Blood vessels: vasoconstriction

- Increased CO and R will increase BP

81

Other methods of blood pressure control

- Chemoreceptors

- Higher brain centers

- Endocrine factors

82

Chemoreceptors

- Monitor oxygen, carbon dioxide, hydrogen ion contents of blood

- Objective: change cardiac output and blood pressure to meet varying metabolic needs of body

83

Higher brain centers

- Cerebral cortex and hypothalamus also relay information

- Communicate with the limbic system; cause of physical manifestation of emotions

84

Endocrine factors

- Antidiuretic hormone (ADH): aka. vasopressin; causes vasoconstriction

- Thromboxane and serotonin: cause vasoconstriction

- Epinephrine and norepinephrine: cause vasoconstriction

85

Aging effects on circulation

- Blood vessels stiffen and narrow due to loss of elasticity, decreased vessel compliance and accumulation of fatty deposits (plaques)

- Stiffened blood vessels cause heightened MAP, which further stiffens blood vessels -> vicious cycle

- Increased risk of myocardial infarction (MI)

- Cardio-protective estrogen effects are lost in post-menopausal women