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Cardiovascular Ch 21
| Question | Answer |
|---|---|
| capillaries | site of exchange with tissues; substances move thru by diffusion |
| continuous capillaries | no gaps between endothelial cells, no fenestrae; less permeable to large molecules. (muscle and nervous tissue) |
| fenestrated capillaries | porous and endothelial cells have fenestrae; highly permeable; |
| sinusoidal capillaries | large diameter w/large fenestrae & less basement membrane, allow large molecules to pass (endocrine glands) |
| sinusoids | larger diameter sinusoidals; (liver, bone marrow) |
| capillary network | blood flows from arterioles thru meatarterioles then thru cap. network; sphincters and smooth muslce regulate flow |
| elastic artery | conductors; largest diameter; high pressure that fluctuates between systolic and distolic |
| muscular artery | smooth muscle regulates blood flow by constricting or dialating; most smaller unnamed arteries |
| arterioles | transfer blood from small arteries to capillaries; like smalll arteries |
| venules | drain capillary network |
| medium veins | go between small and large veins |
| large veins | thin tunica intima |
| tunica intima | internal elastic membrane |
| tunica media | smooth muscle cells around blood vessel; vasoconstriction and dilation |
| tunica externa | connective tissue |
| valves | formed by overlapping flaps in intima; any vein over 2mm has them; more found in veins of lower extremities |
| nerve supply | unmyelinated sympathetic nerve fibers form plexi in tunica adventia :vasoconstriction; parasympathetic inervate penis and clitoris |
| arteriosclerosis | degeneratiopnal changes in arteries making them less elastic |
| artheriosclerosis | plaque deposited in walls |
| pulmonary circulation | from R ventricle to pulmonary trunk->divides into pulmonary arteries; 2 pulm arteries exit each lung and enter L atrium |
| systemic circulation | aorta exits left ventricle and devides into ascending aorta (coronary arteries branch out), aortic arch, and descending aorta and blood flows to body. Veins return blood to heart from body |
| laminar flow | streamline, interior of blood vessel is smooth and equal diameter; outer layer moves slowest and inner fastest |
| turbulent flow | interrupted, flow rate exceeds critical velocity; fluid passes a constriction, sharp turn; contributes to heart sounds |
| blood pressure | measure of force exerted by blood against the wall; moves blood thru vessels; measure by listening to korotkoff sounds: turbulent flow in arteries as pressure is released from blood pressure cuff |
| flow formula | (p1-p2)/r-pie(p1-p2)r4/8vl |
| poiseuille's law | flow decreases when resistance increases |
| resistance | size of blood vessel diameter |
| viscocity | resistance of liquid to flow; as viscocity increases pressure required to flow increases; infuenced by hemocrit( % of RBCs making up blood volume); dehydration or too many RBCs can increase velocity |
| factors effecting blood flow | viscocity, resistance, pressure, length of vessel |
| Net filtration pressure (NFP) | force responsible for moving fluids across capillary walls; effected by hydrostatic and osmostatic pressure (net hydro-net osmo) (pressure in and out). |
| net hydrostatic pressure | blood pressure-interstisial fluid pressure(bp-ifp) |
| net osmotic pressue | blood colloid osmotic pressure-interstisial fluid osmotic pressure(bcop-icop) |
| venous tone | continual state of partial contraction of veins due to sympathetic stimulation |
| effect of gravity on BP | in standing position hydrostatic pressure caused by gravity increases BP above heart and decreases BP above heart |
| local control of blood flow | vasodialtion and precapillary sphincters can increase blood flow 7-8%; capillaries become more dense in areas with regular increased metabolic rate |
| nervous regulation of blood flow | minute to minute regulation of local circulation; sympathetic most important; vasomotor center in lower pons contributes to norepinephrine and epinephrine release |
| baroreceptor reflexes | change peripheral distance, heart rate, and stroke volume in response to changes in blood pressure |
| chemoreceptor reflexes | sensory receptors senstivie to o2, co2 and ph levels of blood |
| CNS ischemic response | high co2 or low ph levels in medulla increases peripheral resistance |
| renin-angiotesin-aldersteron mechanism | low BP stimulates kidneys-> renin hormone-> angiotenin1-> angiotensin convertin enzyme->angiotenin2 goes to adrenal cortex to produce aldosterone, which absorbs sodium and water, which increases blood volume and thus BP |
| vasopressin (adh) mechanism | adh->kidneys, water is obsorbed |
| atrial natriueretic hormone | released from cardiac muscle cells when atrial blood pressure increases-> increase in urine production-> decrease in blood volume and pressure |
| fluid shift | movement of fluid from interstitial spaces into capillaries in response to increased blood pressure |
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