Circulatory System

Question 1

what does the circulatory system consist of?

Answer 1

heart, blood vessels, & lymphatics

Question 2

what layers do blood vessels have?

Answer 2

tunica intima, tunica media, tunica adventitia

Question 3

vasa vasorum

Answer 3

small branched blood vessels through adventitia & outer part of media (veins have more)

Question 4

nervi vascularis

Answer 4

larger vessels have nerves & lymphatics in adventitia

Question 5

tunica intima

Answer 5

endothelium, underlying subendothelial CT, internal elastic lamina in large vessels

Question 6

tunica media

Answer 6

primarily smooth muscle cells & also external elastic lamina

Question 7

tunica adventitia

Answer 7

fibroelastic CT (dense irregular CT with small amounts of elastic fibers)

Question 8

elastic (conducting) arteries

Answer 8

arteries that conduct blood to muscular arteries; aorta, pulmonary, brachiocephalic, common carotid, subclavian, common iliac

Question 9

characteristics of elastic arteries

Answer 9

incomplete internal elastic lamina, thick tunica media, thin adventitia; no distinct external elastic lamina

Question 10

muscular (distributing) arteries

Answer 10

delivers blood to organs; innervated by postganglionic sympathetic nerve fibers

Question 11

characteristics of muscular arteries

Answer 11

well developed internal elastic lamina, thick external elastic lamina

Question 12

arteriole

Answer 12

small artery, tunica media has 1-3 layers of smooth muscle & some elastic fibers

Question 13

capillaries

Answer 13

• very small arteries that drain blood into organ and into veins
• single layer of endothelial cells
• surrounded by pericytes, reticular/collagenous fibers

Question 14

continuous (somatic) capillary

Answer 14

• continuous endothelium & basal lamina (no fenestrae)
• pinocytotic
• location: muscle, CT, CNS, exocrine pancreas, gonads

Question 15

in CNS, what type of tight junction do continuous capillaries have that contributes to the BBB?

Answer 15

occluding junction

Question 16

fenestrated (visceral) capillaries

Answer 16

• attenuated endothelium with large windows with diaphragms covering them (continuous basal lamina)
• location: mucosa of GI tract, endocrine glands, renal, kidney, choroid plexus, & ciliary body

Question 17

where do fenestrated endothelium have no diaphragms?

Answer 17

glomerular capillaries

Question 18

discontinuous (sinusoidal) capillaries

Answer 18

• location: liver & hemopoietic organs such as bone marrow and spleen
• wide gaps between cells (incomplete basal lamina)

Question 19

veins

Answer 19

vessels that return deoxygenated blood to heart (start as venules)

Question 20

layers of veins

Answer 20

• intima: endothelial cells
• media: 1-2 layers of smooth muscle
• adventitia: collagen fibers

Question 21

postcapillary venules

Answer 21

• receive blood from capillaries
• incomplete layer of pericytes
• vasoactive compounds such as histamine & serotonin

Question 22

muscular venules

Answer 22

no pericytes

Question 23

small/medium veins have?

Answer 23

• intima: thin subendothelial CT
• media: reticular/elastic fibers with smooth muscle cells
• adventitia: well developed with smooth muscle & elastic fibers

Question 24

large veins

Answer 24

• superior/inferior vena cava, portal trunk
• thin intima & media
• thick adventitia

Question 25

venous valves

Answer 25

- small to medium size veins have valves to prevent retrograde blood flow (mostly in lower limb) - semilunar folds of intima

Question 26

arteriovenous anastomoses

Answer 26

connections between arterioles & venules with specialized tunica media with a sphincter

Question 27

what controls the amount of blood flowing into capillaries?

Answer 27

precapillary sphincters

Question 28

lymphatic vessels

Answer 28

plasma proteins, fluid, enzymes, lipids, antibodies, hormones etc leak from blood vessels & bathe tissues & interstitial spaces

Question 29

where is lymph recycled to?

Answer 29

back into venous circulation at the base of the neck

Question 30

what are lacteals important for?

Answer 30

important route of fat absorption in intestine

Question 31

where do lymphatic vessels originate?

Answer 31

in CT as closed end anastomosing capillaries

Question 32

what layer do lymphatic vessels do NOT have?

Answer 32

basal lamina

Question 33

what tissues have no lymphatic system?

Answer 33

CNS & bone marrow

Question 34

what prevents the back flow of lymph?

Answer 34

paired cusp valves

Question 35

where are the lymphatics in skeletal muscle located?

Answer 35

only in perimysium

Question 36

atherosclerosis

Answer 36

lipid laden macrophage formation & fatty deposits in intima that may block the vessel

Question 37

restenosis

Answer 37

smooth muscle cell proliferation that follows angioplasty procedure that may occlude vessel

Question 38

aneurysm

Answer 38

ballooning of artery/weakness in artery wall caused by atherosclerosis, syphilis, CT disorders such as ehler's danlos & marfan's

Question 39

varicose veins

Answer 39

tortuous, dilated veins mostly in older people caused by decrease in muscle tone and failure of venous valves

Question 40

prostacyclin

Answer 40

- from arachidonic acid that functions in the regulatory role of endothelial cells - inhibits platelet adhesion & clot formation

Question 41

endothelial cells secrete what compound that causes smooth muscle in tunica media to relax?

Answer 41

nitric oxide (vasodilation)

Question 42

maternal-fetal circulation

Answer 42

maternal blood is NOT continuous with fetal blood except at placenta/umbilical cord