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47 Cards in this Set
- Front
- Back
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Arteries |
transport blood from heart to capillaries |
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Capillaries |
microscopic porous blood vessels exchange substances between blood and tissues |
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Veins |
drain blood from capillaries transport blood back to heart |
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Tunica intima |
innermost layer of vessel |
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Tunica media |
middle layer of vessel |
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Tunica externa |
outermost layer of vessel |
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vasa vasorum |
small arteries required to supply very large vessels |
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Continuous capillaries |
most common type endothelial cells forming continuous lining around lumen tight junctions DONT form complete seal muscle, skin, lungs, CNS |
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Fenestrated capillaries |
endotheliel cells forming continuous lining fenestrations, allow movement of smaller plasma proteins, too small for formed elements small intestine, endocrine glands |
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Sinusoids |
endothelial cells forming incomplete lining openings allow for transport of large substances (formed elements, large plasma proteins) bone marrow, liver/spleen removing aged RBC |
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Capillary beds |
begins fed by metarteriole vessel branch of arteriole connects to postcapillary venule |
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Percapillary sphincter |
smooth muscle at true capillary origin |
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sphincter relaxation |
permits blood flow into true capillaries |
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sphincter contraction |
causes blood to bypass capillary bed |
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vasomotion |
cycle of contracting and relaxing of precapillary sphincter |
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artherosclerosis |
increased cholesterol in blood (hypercholesterolemia) smoking and hypertension TREATMENT: angioplasty or coronary bypass surgery |
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arteriosclerosis |
progressive disease of elastic and muscular arteries hardening is loss of elasticity in vessels due to presence of atheroma (plaque) thickening of tunica intima and narrowing of arterial lumen |
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Pulmonary circuit |
18% of blood r. atrium, r.ventricle, pulmonary trunk, pulmonary arteries, pulmonary arterioles, pulmonary capillaries, pulmonary venules, pulmonary veins, left atrium, l. ventricle, aorta |
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systemic circuit |
70% of blood |
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systolic pressure |
pressure in arteries during ventricular systole, highest pressure generated in arteries |
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diastolic pressure |
pressure in arteries during ventricular diastole, lowest pressure generated in arteries |
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pulse pressure |
additional pressure on arteries when heart contracting highest in arteries closest to the heart difference b/w systolic and diastolic pressures bp: 120/80 pulse pressure=40 |
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MAP |
mean arterial pressure average blood pressure forces on arteries MAP= diastolic + 1/3 pulse pressure bp=120/80 MAP= 80 + 40/3 MAP=93 if less than 60 may indicate insufficient blood flow |
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vasomotor tone |
smooth muscle ususally somewhat constricted regulated by vasomotor center in brainstem |
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capillary exchange |
diffusion, vesicular transport, bulk flow |
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bulk flow |
movement of fluids and dissolved substances direction of movement depends on net pressure of opposing forces HYDROSTATIC AND COLLOID 2 types: filtration and reabsorption |
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filtration |
movement of fluid OUT of blood through openings in capillaries fluid and small solutes larger solutes blocked occurs on arterial end of capillary |
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baroreceptor |
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epinephrine/norepinephrine |
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chemoreceptor reflex |
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long term regulation of blood pressure |
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exercise |
–Increasein totalblood flow dueto fasterand stronger heartbeat –Alsodue to blood removal from venous reservoirs–Ensuresmetabolically active tissues receiving adequate blood–Increasedflowto coronaryvessels•helpsensure sufficient oxygen reaches cardiac muscle–Skeletalmuscle blood flow increasing•neededto meet high metabolic demands–Increasedpercentage of blood flow to skin•tohelp dissipate heat–Relativelyless blood•toabdominal organs, kidneys, less metabolically active structures |
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blood pressure reading |
given as ratio systolic/diastolic average adult: 120/80 mm Hg |
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reabsorption |
(bulk flow) movement of fluid back INTO blood occurs on venous end |
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hydrostatic pressure |
physical force exerted by fluid on a structure HPb= blood hydrostatic pressure- promotes filtration from capillary HBif= interstitial fluid hydrostatic pressure-force of interstitial fluid on external blood vessel close to 0 in most tissues |
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colloid pressure |
pull of water into tissue by tissues protein concentration COPb= blood colloid osmotic pressure- draws fluid into blood due to blood proteins, promotes reabsorption COPif= interstitial fluid colloid osmotic pressure- force drawing fluid into interstitial fluid relatively low (0-5 mm Hg) |
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Short term Regulation |
local regulation in response in metabolic activity of tissues oxygen and nutrient levels DECLINING INCREASE in carbon dioxide, lactic acid, H+, K+ act as local vasodilators |
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vasodilators |
dilate arterioles and relax precapillary sphincters increase flow into capillary beds |
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vasoconstrictors |
constrict arterioles and contraction on precapillary sphincters decrease flow into capillary beds |
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Cardiogenic Shock |
due to hearts inability to function properly, results in decreased cardiac output, seen with myocardial infarction |
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Hemorrhagic Shock |
reduced blood volume due to hemorrhaging, blood loss |
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Anaphylactic Shock |
blood volume is normal but release of inflammatory substances cause extreme vasodilation and increase in capillary permeability (allergic reactions) causes severe DROP IN BP |
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Hypertension |
chronically elevated blood pressure >140 systolic |
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Hypotension |
chronically low blood pressure <90 systolic |
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Total blood flow |
flow proportional to pressure gradient divided by resistance F = /\P/R |
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Discuss the mechanisms and various pressures involved in the movement of fluidsbetween capillaries and tissues.
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Bulk FlowThe mass movement of fluids into and out of capillary bedsrequires a transport mechanism far more efficient than mere diffusion. Thismovement, often referred to as bulk flow, involves two pressure-drivenmechanisms: Volumes of fluid move from an area of higher pressure in acapillary bed to an area of lower pressure in the tissues via filtration. Incontrast, the movement of fluid from an area of higher pressure in the tissuesinto an area of lower pressure in the capillaries is reabsorption. Two types ofpressure interact to drive each of these movements: hydrostatic pressure andosmotic pressure.The primary force driving fluid transport between thecapillaries and tissues is hydrostatic pressure, which can be defined as thepressure of any fluid enclosed in a space. Blood hydrostatic pressure is theforce exerted by the blood confined within blood vessels or heart chambers.Even more specifically, the pressure exerted by blood against the wall of acapillary is called capillary hydrostatic pressure (CHP), and is the same ascapillary blood pressure. CHP is the force that drives fluid out of capillariesand into the tissues.The net pressure that drives reabsorption—the movement offluid from the interstitial fluid back into the capillaries—is called osmoticpressure (sometimes referred to as oncotic pressure). Whereas hydrostaticpressure forces fluid out of the capillary, osmotic pressure draws fluid backin. Osmotic pressure is determined by osmotic concentration gradients, that is,the difference in the solute-to-water concentrations in the blood and tissuefluid. A region higher in solute concentration (and lower in waterconcentration) draws water across a semipermeable membrane from a region higherin water concentration (and lower in solute concentration).-src 'n,/
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2.How and why does angiotensin II get formed?
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Converted from angiotensin I by a converting enzyme (ACE);powerful vasoconstrictor- raises blood pressure, stimulates thirst center,increasing blood volume and pressure, stimulates release of aldosterone andantidiuretic hormone, acts on kidneys to decrease urine formation
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