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Cardiovascular Ch 21

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
Created by: 619572525