Vascular Physiology

Question 1

what % of blood volume in arteries/veins/caps?

Answer 1

5% in capillaries. 30% in arteries/heart. 65% in veins (like capacitance vessels)

Question 2

3 main layers in every blood vessel

Answer 2

tunica intima, media and adventitia aka serosa

Question 3

what is tunica intima made out of?

Answer 3

thin layer separating blood from wall tissue, 1 endothelial layer

Question 4

what is in tunica media? adventitia?

Answer 4

media: smooth muscle layer, thicker in high pressure arterial vessels. smooth muscle cells + elastin. adventitia = connective tissue outer lining

Question 5

high pressure aorta and arteries have a lot of? which allows for?

Answer 5

elastic mixed inside the media. expand with systolic pressure surge and rebound when arterial pressure drops = helps smooth arterial pressure and decreases difference between systole and diastole

Question 6

endothelium: what? not just what? controls what?

Answer 6

single layer of cells with minor amount of sub cellular thickness. not just passive coating of arteries, it has major vessel altering functions. controls nutrients in/waste out of vessels

Question 7

when endothelium activated, what happens? glycocalyx?

Answer 7

release of chemical mediators. anticoagulant factors in the glycocalyx.

Question 8

smooth muscle activation sequence

Answer 8

calcium enters in response to depolarization, binds calmodulin, activates myosin light chain kinase

Question 9

calcium contraction of smooth muscle is ____? which means?

Answer 9

graded = more calcium available = greater contraction

Question 10

connective tissue: cells adhere via? then adhere to ECM via?

Answer 10

cadherins. integrins

Question 11

ECM is what? contains what?

Answer 11

non cell parts of the vessel = collagen, glycoproteins, proteoglycans, matrix metalloproteinases

Question 12

vessel remodeling: vessels are not ___? they can?

Answer 12

not static, they can change thickness of walls, internal diameter in response to stimuli aka vessel can grow and shrink as needed

Question 13

endothelium: resting state vs. activated?

Answer 13

resting = anti clotting, vasodilatory, anti inflammatory. activated = pro clotting, pro inflammatory, vasoconstricting

Question 14

endothelium releases what vasodilatory factors?

Answer 14

NO, PGI2, EDHF (endothelial dependent hyperpolarizing factor. serotonin, adenosine, PTH rP, CO, H2S

Question 15

endothelium: release what vasoconstrictors when activated?

Answer 15

most potent = endothelin. also: angiotensin II, thromboxanes, histamine, loses glycocalyx

Question 16

Ohm’s law equivalent for blood pressure

Answer 16

pressure = heart rate X stroke volume X vascular resistance (pressure = flow aka cardiac output X resistance)

Question 17

vascular resistance: proportional to?

Answer 17

inversely proportional to r^4

Question 18

does the body maintain flow or pressure?

Answer 18

pressure –> body tries to keep BP constant and allows each organ to change resistance (and thus change flow)

Question 19

how do we maintain BP?

Answer 19

pressure sensors aka baroreceptors in carotid sinus and aortic arch sense inadequate pressure = activity increases, activates sympathetic system = increase heart rate/contractility/vessel tone

Question 20

why does pressing on carotids = fainting?

Answer 20

press = raise pressure on carotid bodies = mimics too high BP. reflex decrease sympathetic and increase parasympathetic = decrease CO/vascular resistance = decrease BP = decrease brain blood flow