Lecture 23: Heart Vessels Microstructure, Content (1/2) Flashcards Preview

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Flashcards in Lecture 23: Heart Vessels Microstructure, Content (1/2) Deck (47):
1

flow of blood, from capillary to vein

capillary >
poscapillary venule >
venule >
small (muscular) vein >
medium (muscular) vein >
large vein

2

walls of arteries/large veins

3 concentric layers, called tunics

3

tunics of blood vessel walls

tunica intima (inner)
tunica media (middle)
tunica adventitia (out)

4

characteristics of tunica intima

endothelium and its basement membrane

subendothelial CT

internal elastic lamina

5

tunica media characteristics

elastic fiber - external elastic lamina; collagen fiber, ground substance, smooth muscle cells

6

vasa vasorum

vessels of the vessel
associated with walls of arteries

7

what mediates vasoconstriction of the vessel wall?

smooth muscles in the t. media's postganglionic sympathetic nerves

8

laminae

sheaths/layers of fenestrated elastic membrane that make up artery wall

9

elastic artery (i.e. aorta) characteristics

40-70 sheets of fenestrated elastic membranes (laminae)

external and internal elastic lamina, not conscpicious

vasa vasorum and nerves in t. adventitia

10

what has thinner t. media- elastic artery or large vein?

large vein

11

what can be described as physiologically conducting vessels?

elastic arteries

12

how elastic arteries work, physiologically

aorta and its major branches

lots of elastic tissue in wall --> distend as fill with blood during systole

during diastole (while heart fills), elastic recoil of artery --> blood moves along vessels --> maintains arterial pressure

13

examples of large veins

superior venae cavae, inferior venae cavae

14

what could be called reservoir vessels or compliance vessels?

veins

15

how veins work, physiologically

pressure in venous system is low, continues to drop as veins go to heart

vein walls are thin, distensible, compliant; they act as reservoir for blood collected from other vasculature

16

neurovascular bundle

artery, vein, nerve together

17

what type of artery/vein tend to go together?

muscular artery, medium muscular vein

18

does muscular artery or medium vein have thicker wall?

artery

19

does muscular artery or medium vein t. media have more elastic fiber?

vein

20

how many layers of smooth muscle in t. media of muscular artery?

up to 40

21

muscular artery or medium vein have larger t. adventitia?

muscular artery

22

examples of muscular arteries

brachial, femoral, coronary arteries

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characteristics of muscular arteries

large proportion of muscle, low resistance to blood flow, allows rapid blood distribution to tissues

24

divisions of muscular arteries

branching muscular arteries > small muscular arteries > arterioles

25

medium veins characteristics

companion veins of muscular arteries

have valves

are collecting vessels (from arterial system)

26

distributing arteries

muscular arteries

27

what tissue layer forms valve of medium veins?

t. intima

28

how does valve of medium vein work?

valve opens; pushes blood upstream; gravity causes blood to backflow; backflow facilitates valve's closing

29

IEL

internal elastic lamina

outermost part of t. intima

elastic tissue

30

how many smooth muscle layers in t.media of small (muscular) artery?

3-10

31

how many smooth muscle layers in t.media of small (muscular) vein?

few smooth muscles in wall

32

how many smooth muscle layers in t.media of small (muscular) arteriole?

1-3

33

how many smooth muscle layers in t.media of small (muscular) venule?

few
(has very irregular lumen)

34

what do arterioles control?

systemic blood pressure

35

what controls arteriole diameter?

contraction of smooth muscle in response to sympathetic neural and non-neural stimuli

36

what does arteriole contraction cause?

increases resistance to blood flow; pressure in muscular and elastic arteries rule

37

what are resistance vessels?

arterioles

38

microcirculation flow

from heart > artery > arteriole > capillary bed > venule > vein > to heart

39

how many RBC can capillary lumen accommodate?

1

40

characteristics of postcapillary venules

10-25 um diameter; 3x capillary

endothelium more permeable than capillary

where WBC emigrate from blood circulation, esp during inflammation

41

what vessels handle inflammation?

postcapillary venules

42

what are pericytes

replace smooth muscle cells in postcapillary venules, capillaries

contractile proteins (actin, myosin, tropomyosin)

regulates blood flow through capillaries

can differentiate into smooth muscle, endothelial cells in response to injury or stimulation by growth factors

43

capillaries

site of gas, fluid, nutrient, metabolic waste exchange between blood/tissue

are metabolic exchange vessels

44

continuous capillaries

muscles, brain, lungs, bone

45

fenestrated capillaries

intestines, endocrine glands, kidneys

fenestrations in endothelial cells, continuous basal lamina

rapid transport of fluid, nutrients, hormones from tissue of cell/organ into circulation

46

discontinuous (sinusoids) capillaries

liver, bone marrow, spleen

47

what does liver sinusoid have

fenestrated endothelium so have bidirectional flow between hepatocyte and cytosol

no basement membrane