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

Question 1

flow of blood, from capillary to vein

Answer 1

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

Question 2

walls of arteries/large veins

Answer 2

3 concentric layers, called tunics

Question 3

tunics of blood vessel walls

Answer 3

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

Question 4

characteristics of tunica intima

Answer 4

endothelium and its basement membrane

subendothelial CT

internal elastic lamina

Question 5

tunica media characteristics

Answer 5

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

Question 6

vasa vasorum

Answer 6

vessels of the vessel

associated with walls of arteries

Question 7

what mediates vasoconstriction of the vessel wall?

Answer 7

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

Question 8

laminae

Answer 8

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

Question 9

elastic artery (i.e. aorta) characteristics

Answer 9

40-70 sheets of fenestrated elastic membranes (laminae)

external and internal elastic lamina, not conscpicious

vasa vasorum and nerves in t. adventitia

Question 10

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

Answer 10

large vein

Question 11

what can be described as physiologically conducting vessels?

Answer 11

elastic arteries

Question 12

how elastic arteries work, physiologically

Answer 12

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

Question 13

examples of large veins

Answer 13

superior venae cavae, inferior venae cavae

Question 14

what could be called reservoir vessels or compliance vessels?

Answer 14

veins

Question 15

how veins work, physiologically

Answer 15

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

Question 16

neurovascular bundle

Answer 16

artery, vein, nerve together

Question 17

what type of artery/vein tend to go together?

Answer 17

muscular artery, medium muscular vein

Question 18

does muscular artery or medium vein have thicker wall?

Answer 18

artery

Question 19

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

Answer 19

vein

Question 20

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

Answer 20

up to 40

Question 21

muscular artery or medium vein have larger t. adventitia?

Answer 21

muscular artery

Question 22

examples of muscular arteries

Answer 22

brachial, femoral, coronary arteries

Question 23

characteristics of muscular arteries

Answer 23

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

Question 24

divisions of muscular arteries

Answer 24

branching muscular arteries > small muscular arteries > arterioles

Question 25

medium veins characteristics

Answer 25

companion veins of muscular arteries

have valves

are collecting vessels (from arterial system)

Question 26

distributing arteries

Answer 26

muscular arteries

Question 27

what tissue layer forms valve of medium veins?

Answer 27

t. intima

Question 28

how does valve of medium vein work?

Answer 28

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

Question 29

IEL

Answer 29

internal elastic lamina

outermost part of t. intima

elastic tissue

Question 30

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

Answer 30

3-10

Question 31

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

Answer 31

few smooth muscles in wall

Question 32

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

Answer 32

1-3

Question 33

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

Answer 33

few

has very irregular lumen

Question 34

what do arterioles control?

Answer 34

systemic blood pressure

Question 35

what controls arteriole diameter?

Answer 35

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

Question 36

what does arteriole contraction cause?

Answer 36

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

Question 37

what are resistance vessels?

Answer 37

arterioles

Question 38

microcirculation flow

Answer 38

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

Question 39

how many RBC can capillary lumen accommodate?

Answer 39

1

Question 40

characteristics of postcapillary venules

Answer 40

10-25 um diameter; 3x capillary

endothelium more permeable than capillary

where WBC emigrate from blood circulation, esp during inflammation

Question 41

what vessels handle inflammation?

Answer 41

postcapillary venules

Question 42

what are pericytes

Answer 42

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

Question 43

capillaries

Answer 43

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

are metabolic exchange vessels

Question 44

continuous capillaries

Answer 44

muscles, brain, lungs, bone

Question 45

fenestrated capillaries

Answer 45

intestines, endocrine glands, kidneys

fenestrations in endothelial cells, continuous basal lamina

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

Question 46

discontinuous (sinusoids) capillaries

Answer 46

liver, bone marrow, spleen

Question 47

what does liver sinusoid have

Answer 47

fenestrated endothelium so have bidirectional flow between hepatocyte and cytosol

no basement membrane