Blood Vessel Histology

Question 1

How are the walls of blood vessels innervated in general terms?

Answer 1

by postanglionic, unmyelinated sympathetic nerve fibers which cause vsoconstriction

Question 2

What are the examples of elastic (conducting) arteries?

Answer 2

aorta, common carotid, sublcavian, common iliac, pulmonary trunk

Question 3

Why do the elastic conducting arteries appear yellowish in fresh state?

Answer 3

because they have an abdunance of yellow elastin

Question 4

In the elastic conducting arteries, which way are the endothelial nuclei oriented? smooth muscle nuclei?

Answer 4

endothelium - longitudinally

smooth muscle - circumferentially

Question 5

What are the membrane-bound inclusions contained in arterial endothelial cells?

Answer 5

weibel-palade bodies

Question 6

What do the weibel-palade bodies contain?

Answer 6

von willebrand factor, which facilitates coagulation of platelets during clot formation

Question 7

What is the tunica medial comprised of in elastic conducting arteries?

Answer 7

many fenestrated lamellae of elastin - like swiss cheese lasagna

Question 8

What is the dominant component of the tunica medial in elastig conducting arteries?

Answer 8

elastin

Question 9

What’s special about the ECM in the elastic conducting arteries?

Answer 9

it’s secreted by smooth muscle cells, not fibriblasts

Question 10

What blood vessle is contained int he tunica dventitia in the elastic conducting arteries?

Answer 10

vasa vasorum - blood vessel to the vlood vessles

Question 11

Most of the named arteries fall into what cateogy of artery?

Answer 11

muscular distributing arteries

Question 12

What is the chief characteristic of the musculuar distributing arteries?

Answer 12

thick tunica media comprised primarily of smooth muscle cells

Question 13

Although the tunica intima is htinner than that observe in elastic arteries, what layer of it is more prominent?

Answer 13

the internal elastic lamina - it’s the boundary between the intima and media

Question 14

What do the outermost endothelial cells of the intima made gap junctions with?

Answer 14

the outermost smooth muscles cells of the tunica media - via gap jucnitons

Question 15

What is the range in # of smooth muscle cell layers in the musclar arteries?

Answer 15

small ones - only 3-4 layers

large ones - up to 40 layers

Question 16

What is the boundary between the media and adventitia in muscular arteries?

Answer 16

external elastic lamina

Question 17

What is the typical diameter of the arterioles?

Answer 17

less than 0.1 mm

Question 18

What controls blood flow into the capillary bed by encircling the vessel where a capillary springs from?

Answer 18

metarterioles - smooth muscle cells that act as sphincters

Question 19

what do the carotid sinuses sense?

Answer 19

blood pressure changes - they’re barorectpros

Question 20

Where are the carotid sinuses?

Answer 20

in the wlalls of the internal carotid artery (just above the bifurcation of the common carotid arteries)

Question 21

What nerve endings are involved in the carotid sinuses?

Answer 21

glossopharygneal

Question 22

What are the carotid bodies and aortic bodies?

Answer 22

chemoreceptors that sense changes in oxygen, carbon dioxide and protons in the blood and send the signal via the glossopharyngeal and vagus nerves

Question 23

What is the typically diameter of capillaries?

Answer 23

8-10 micrometers

Question 24

What type of vesicles are associated with eh ppasmalemma of capillaries? what are they for?

Answer 24

pinocytic vesicles used to transport substance across the membrane

Question 25

What cells are found outside the capillaries and small venules with primary and secondary processes which run longitudinally and circumferentally along and around the capillary

Answer 25

pericytes

Question 26

What is the likely function of pericytes

Answer 26

they're probably contractile and help regulate blood flow through the capillaries upon damage they probably give rise to smooth muscle and endothelial cells

Question 27

What are the three types of capillaries?

Answer 27

conitnuous capillaries fenestrated capillaries sinusoidal capillaries

Question 28

Where are continuous capillaries found?

Answer 28

muscle, nervous and CT

Question 29

What makes fenestrated capillaries different from continuous capillaries?

Answer 29

fenestrated have pores in the wall while continuous don't

Question 30

What are the pores covered by ?

Answer 30

a thun diaphragm probably made with glycocalyx

Question 31

Where in the body are fenestrated capillaries found/

Answer 31

pancreas, intestine and endocrine glands

Question 32

Of the three types of capillaries, which have small diameters and which have bigger diamaters?

Answer 32

continuous and fenestrated are small | sinusoidal is large

Question 33

What makes the fenetrates of the sinusoidal capillaries different from the fenestrated capillaries found?

Answer 33

they're larger and don't have diaphragms

Question 34

What organs are the sinusoidal capillaries found/

Answer 34

``` bone marrow liver spleen lmphoic organs some endocrine organs ```

Question 35

What are the two ways we regulate blood flow into a capillary bed?

Answer 35

1. ateriovenous anastomoses | 2. central channels

Question 36

What is an arteriovenous anastomosis? How does it work?

Answer 36

it's where an artery joins a venous channel if the shunt is open, blood will bypass the capilary bed through the anastomosis If the shunt is closed, the blood passes into the capillary bed

Question 37

What is the important role of the arteriovenous anastomoses?

Answer 37

temperature regulation on the skin

Question 38

What is the central channel?

Answer 38

It's the straight shot from arteriole to venule composed of a metarteriole on the arteriole side and a thoroughfar channel on the venous side blood will pass thorugh the central channel if the sphincters are closed

Question 39

What molecules are expressed on the luminal side of capillaries to bind leukocytes and help them pass through

Answer 39

1. selectins (P and E) help the leukocytes to stop roling | 2. Integrins bind them even more strongly and help them diapedese

Question 40

What are some of the general functions that endothelial cells can do?

Answer 40

1. produce prostacyclin, plasminogen activator, IL-1, growth factors, etc. 2. have enzymes that convert angiotensin I to II (and other activating enzymes) 3. adipose tissue endothelium have enzymes on the luminal surface of capillaries to break down lipoprotiens into fatty acids and triglycerides for storage

Question 41

Which are greater in number - veins or arteries?

Answer 41

veins - they hold almost 70% of th total blood volume

Question 42

What sort of capillary are the postcapullary venules potentially mistaken for if you don't know what tissue you're in?

Answer 42

sinusoidal

Question 43

What replaces the pericytes in larger venules?

Answer 43

smooth muscle cells

Question 44

Which is the preferred site for leukocytes migration - capillaries or post capillary venules? why?

Answer 44

postcapillary venules because the walls are more permeable than those of capillaries

Question 45

What are high endothelial venules and how are they different from regular venules?

Answer 45

they ser specialized venules in lymphatic organs where the endothelium is cuboidal rather than squamous

Question 46

Which is the thickest layer in medium veins?

Answer 46

the adventitia. NOT the media!

Question 47

What are examples of alrge veins?

Answer 47

venae cavae, pulmonary veins, portal, renal, internal jugular, iliac, azygous

Question 48

Describe the tunica media in large veins

Answer 48

not well developed - often not apparent at all

Question 49

What is unique about the tunica adventitia in large veins?

Answer 49

the smooth muscle cells are located here instead of in the meda and they're oriented longitudinally, no circumferentially

Question 50

What are vericose veins?

Answer 50

abnormally large and tortuous veins- usually the superficial leg veins of older people due to loss of muscle tone, wall degeneration and valvular incompetence

Question 51

What veins have valves -

Answer 51

many small and medium-sized veins, but only some large veins | most in the limbs, some in the throax and abdomne, none in the brain and spinal cord

Question 52

What are the valves composed of?

Answer 52

folds of intima endothelium with connective tissue core rich in elastic fibers

Question 53

How do lymph capillaries differ from blood capillaries?

Answer 53

1. larger diameter 2. end blindly in tissue 3. have scanty basement membrane 4. endothelial cells are separated by substantial spaces and held together by few tight junctions

Question 54

How do lymph collecting vessels differ from veins?

Answer 54

walls are thinner | valves ar emore closely spaced because of the passive nature of lymph flow