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39 Cards in this Set
- Front
- Back
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3 layers of blood vessel walls |
tunica intima- inner most endothelium media- layer of smooth muscle vasoconstrics and vasodialation externa- loosen woven collagen fibers- vasa vasorum- tiny blood vessels that feed larger ones |
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structure and function of arteries |
elastic/conducting- thick walled near heart, largest and has most elastic due to lots of press. muscular(distributing)- distal to elastic, deliver blood to body organs, thickest tunic media b/c how much pressure to send to each organ arterioles- smallest have all 3 tunics, media mostly smooth little elastic, diameter crucial in getting organs proper blood |
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types of capillaries |
continous cap- less flow through them, abundant in skin and muscle, tj are incomplete and allow intracellular clefts brain cap lack these creating BBB fenestrated cap- has pores or windows, found where cap absorbtion or filtrate sinusoids cap- highly modified, leaky, in liver, spleen, bm, adernal medulla, lg irregular lumen, fenestrated allows lg molecules to pass bf slow liver needs time to remove toxins |
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Capillary bed |
interweaving network of cap. microcirculation flow from arteriole to cap to venule true capillary- the precapillary sphincters open and allow blood thru the true cap thoroughfare- pre. sphincters closed blood direct line thru vascular shunt metarteriole and thoroughfare channel |
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venules |
formed when cap unite, postcap venule (smallest) composes of endothelium surround by pericytes very porous allow fluid and WBC to pass LG venules have 2 layers of smooth muscle and thin externa |
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veins |
formed when venules join 3 layered like arteries but thinner and have lger lumen, tunica externa thickest and contains bundles |
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vascular anastomosis |
prevent loss of bf to rest of body, common in joints, ab organs, brain and heart not in retina, spleen and kidney arterial anastomosis- web of interconected arteries feeding one organ or region, if blocked will take another path |
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blood flow |
volume of blood flowing through a vessel |
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blood pressure |
force per unit area exerted on vessel walls mmHg |
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resistance |
opposition to flow friction created by wall -viscosity of blood over hydrated thin blood -bv diameter lger diameter less friction vasoconstriction- more resistance less flow vasodilation- less resistance more flow |
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arterial blood pressure |
1- how much elastic arteries closest to heart can be stretched 2- vol of blood forced into them at anytime diastole- 2x longer than systole so MAP not 1/2 way pt MAP= dias press+( pulse press/3) |
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capillary blood pressure |
entry into cap bed 35mmhg after 15mmhg this is good b/c 1. cap are fragile and high pres. would rupture. 2. most cap are permeable so high bp would force everything out |
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venous blood pressure |
consistant at 15mmhg needs help pumping 1. respiratory pump inhale ab pr. forces blood to heart 2. muscular pump skeletal muscle contracts squeezes veins and moves blood 3. smooth muscle constriction under sympathetic control |
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short term nerual control bp |
works by altering peripheral resistance (and CO) goals 1. maintain adequate MAP by altering vessel diameter 2.. altering blood distribution to physiological needs |
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vasomotor center |
baroreceptors- pressure sensitive mechanoreceters respong to change in aterial pres and stretch located around neck and heart
chemoreceptor- sense CO2 rising, ph falling, O2 falling, signal cardioacceleratory center to increase CO and vasomotor to stimulate vasoconstriction |
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higher brain centers |
medulla oblongata and brain stem have centers to aid in control of bp cerebral cortex and hypothalamus can activate/inhibit control centers |
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hormones in BP |
atrial natriuretic peptide- lowers BP dilation NE and epinephrine-inc BP and res constric angiotension antiuretic |
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long term renal (kidney) reg. BP |
direct method- independent of hormones, bv/bp increase rate of filtration speeds up, kidney cant process fast enough, stays in urine bp and v fall inderect- renin angiontensis release hormone |
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vital signs |
pulse- presure waves felt in artery from surface pressure points- some points can be pressed to prevent hemerrhage BP- measured in brachial artery in arm hypotension- low bp systolic pres less than 100 hypertension- high bp 140 problem at 160 |
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velocity of blood flow |
farther away from the aorta bf velocity slows slow cap flow is important for exchanges between blood and tissue moves from cap (4500cm3) to vena cava 8 cm3 velocity increase depending on skeletal pump |
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autoregulation local bf reg |
dif organs need more/less supply of blood reg. occurs thru modifying diam. of local arterioles 1. metabolic/chemical 2. myogenic/physical |
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metabolic controls |
lower level of o2 and accumulation of metabolic waste stimulate autoreg waste can directly relax vascular smooth muscle can cause NO release NO powerful vasodilater endothelium releases endothelins that act as vasoconstrictors |
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myogenic control |
vascular smoot muscle repsong to passive stretch w/ inc tone, which resist stretch casuse vasoconstrict reduce stretch= vasodilation reactive hypermia- inc bf after blood flow has been cutoff temp. resulst from both myo and meta |
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long term autoreg |
angiogenisis- formation # of bv in region not getting enough bs increase and existing vessels enlarge common in coronary vessels |
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bf in skeletal muscle at rest |
1 L blood/min 25% cap open cap density of bf inc in red (slow oxidative) than white (fast glycolytic) myogenic and general nerual mech predominate |
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bf in active skeletal |
bf inc in direct proportion to their metabolic activity, excercise, hypermia occurss entirely in response to low o2 concentration and high metabolic factors NE- vasoconstriction increase 10x more from resting |
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bf in brain |
has both metabolic and myogenic MAP dec. cerebral vessels dilate to insure adequate perfusion MAP inc cerebral vessels constrict protects small vessels |
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BF in skin |
supplies nutrients to cell, aids in body temp. reg, provides blood reservoir depending on body temp plexuses can accomodate by changing from 50 ml to 2500 bradykinin- stimulate the vessels endothelial cells to release NO |
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bf in lungs |
02 rereoute when blockage is present like anastomes short pathways consisting of arteries and arterioles less bp needed to propel blood through lungs dec o2 constrics inc o2 dilates opposite to other tissue |
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bf in heart |
fast HR does not allow sufficient gas exchange at rest bf 250 remains constant while coronary pres varies bf may inc 3-4x cardiac cells use 65% o2 carried to them opposed to 25% by others |
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4 routes across cap |
1- diffusion across membranes for lipid soluble molecules ( gases) 2- fluid filled intracellular cap clefts for small h2o soluble solutes like sugar 3- fenestration same molecules as #2 4- active transport for lg molecules (proteins) via pinocyte |
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fluid movement bulk flow |
20 L of fluid are filtered out of cap per day 7x total plasma volume direction and amount of flow reflects balance between hydrostatic and osmotic pressure |
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hydrostatic pressure |
actual BP cap. hydro pres HPc tends to force fluids out through cap walls BP dec as volume dec intersitiual fluid HPif opposes HPc pushing from outside in on walls usually no press net hydro pres= HPc-HPif HPif usually 0 |
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osmotic pressure |
forces opposing Hp created by lg non diffusible molecules (plasma protein) that can't cross cap wall molecules encourage osmosis Cap colloid Op OPc= 26 mmhg OPif= 1 |
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net filtration pressure NFP |
fluid lost organized by body fluid exits if net HP is higher than OP fluid enters if net HP is lower than OP |
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circulatory shock |
any condition in which blood vessels are inadequately filled and blood cannot circulate normally |
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hypovolemic shock |
dec blood volume blood loss, acute hemorrhage, extensive burns |
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vascular shock |
bv normal circulation is poor, result in expansion of vascular bed anaphylactic shock, sun bathing, septicema |
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cardiogenic shock |
pump failure, myocardial infarction heart attack |
