Vascular Physiology Flashcards
what % of blood volume in arteries/veins/caps?
5% in capillaries. 30% in arteries/heart. 65% in veins (like capacitance vessels)
3 main layers in every blood vessel
tunica intima, media and adventitia aka serosa
what is tunica intima made out of?
thin layer separating blood from wall tissue, 1 endothelial layer
what is in tunica media? adventitia?
media: smooth muscle layer, thicker in high pressure arterial vessels. smooth muscle cells + elastin. adventitia = connective tissue outer lining
high pressure aorta and arteries have a lot of? which allows for?
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
endothelium: what? not just what? controls what?
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
when endothelium activated, what happens? glycocalyx?
release of chemical mediators. anticoagulant factors in the glycocalyx.
smooth muscle activation sequence
calcium enters in response to depolarization, binds calmodulin, activates myosin light chain kinase
calcium contraction of smooth muscle is ____? which means?
graded = more calcium available = greater contraction
connective tissue: cells adhere via? then adhere to ECM via?
cadherins. integrins
ECM is what? contains what?
non cell parts of the vessel = collagen, glycoproteins, proteoglycans, matrix metalloproteinases
vessel remodeling: vessels are not ___? they can?
not static, they can change thickness of walls, internal diameter in response to stimuli aka vessel can grow and shrink as needed
endothelium: resting state vs. activated?
resting = anti clotting, vasodilatory, anti inflammatory. activated = pro clotting, pro inflammatory, vasoconstricting
endothelium releases what vasodilatory factors?
NO, PGI2, EDHF (endothelial dependent hyperpolarizing factor. serotonin, adenosine, PTH rP, CO, H2S
endothelium: release what vasoconstrictors when activated?
most potent = endothelin. also: angiotensin II, thromboxanes, histamine, loses glycocalyx
Ohm’s law equivalent for blood pressure
pressure = heart rate X stroke volume X vascular resistance (pressure = flow aka cardiac output X resistance)
vascular resistance: proportional to?
inversely proportional to r^4
does the body maintain flow or pressure?
pressure –> body tries to keep BP constant and allows each organ to change resistance (and thus change flow)
how do we maintain BP?
pressure sensors aka baroreceptors in carotid sinus and aortic arch sense inadequate pressure = activity increases, activates sympathetic system = increase heart rate/contractility/vessel tone
why does pressing on carotids = fainting?
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
