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42 Cards in this Set
- Front
- Back
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what are the three types of capillaries
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continuous, sinusoidal, fenestrated
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describe continuous capillaries
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most common, in muscles and skin, structural basis of blood-brain-barrier, endothelial cells=uninterrupted lining
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describe sinusoidal capillaries
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leaky/ in liver, bone marrow, spleen, adrenal medula/fenestrated w/ irregular lumens/passage of large molecules and blood cells
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describe fenestrated capillaries
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eliptical pores or fenestrations/more permeable to fluids and small solutes/ located where active cappillary absorbtion occurs (small intestines, endorine organs, kidneys)
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what do veins and arteries/arterioles serve as (blood aspect)
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veins-capacitance vessels
arteries/arterioles-resistance vessels |
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what is/are anastomoses
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interconnection of vascular channels
arterial-around joints, organs, brian arteriovenous-metarterioles-shunts venous-common and abundant |
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how does pressure and resistance affect bloodflow
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R is more important in influencing BF, P results when flow is apposed by R, Flow indirectly proportional to resistance
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What is the relationship between resistance and vessel radius
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the bigger the vessel the less resistance because less friction against walls
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how do you find the MAP
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Map=Dp+(PP/3)
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How do you find PP
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Systolic Pressure-Diastolic Pressure
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What does cardiac output and resistance both influence
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vascular pressure
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describe short term mechanisms of bp
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mediated by nervous system and bloodborne chem.//Maintains MAP by altering vessel diameter and CO, alters blood dist. for spec. demands of organs
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Describe long term mechanisms of bp
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mediated by renal mech./counter fluxuations by altering blood volume/Baroreceptors adapt to prolonged ^ or v in pressure/kidneys restore+maintain it
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What does the vasomotor center do
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changes diameter of blood vessels, located in medulla, innervates smooth muscles in vessels, actively modifies by baroreceptors, chemoreceptors and higher brain centers
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how do the kidneys directly effect blood volume
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alters independently of hormones, rate at which fluid filters from bloodstream into kidney tubules is sped up
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how do the kidneys indirectly affect blood volume
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renin-angiotensin mechanism, bp v so kidneys release renin, renin catalyzes making angiotension II, Angiotension-vasoconstritor that stimulates aldosterone secretion, promotes ADH
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What is autoregulation
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automatic adjustment of flow to tissue in proportion to its requirements
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describe the metabolic controls and what some are
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stimuli for auto regulation
NO-vasodilator acts via cGMP 2nd messenger system Endothelins-potent vasoconstrictors |
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what is myogenic control/response
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smooth muscle responds to passive stretch arising via ^ intravascular pressure w/ increased tone
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what is hydrostatic pressure
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force exerted by fluid pressing against a wall, it forces fluids through capillary walls and apposed by HP of the interstitial fluid
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What is osmotic pressure
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force opposing HP and pulls fluid into capillary, created by presence of large nondiffusable molecules
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Explain Hydrostatic pressure and osmotic pressure interactions
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determine Net filtration pressure by, NFP=(HPc-HPif)-(OPc-OPif), at any point along capillary fluid leaves if net Hp>net OP, enters capillary if net OP> net HP
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What is systole
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ventricular contraction
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what is diastole
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ventricular relaxation
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what is autorhymicity and what does the SA node have to do with it
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automaticity- ability to initiate its own beat
rhythmicity- regularity of such pace-making activity SA node generates impulses at greatest frequency |
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How do the different branches of the heart affect the heart rate
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SNS-increase rate and force
PNS-decrease rate |
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what information does an ECG provide
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anatomical orientation of heart, relative size of chambers, various disturbances of rhythm and conduction, ischemic damage to myocardium, influence of drugs, effects of electrolyte concentrations
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how long does the cardiac cycle last
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.8s in total, .1 for atrial systole, .3 for ventricular systole, .4 for total heart relaxation
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What are the steps in the cardiac cycle
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ventricular filling(atrial systole), ventricular systole, early diastole
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describe ventricular filling
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atrial systole/mid to late diastole, sl valves are closed, 80% of vent. filling is passive, P-wave creates slight atrial pressure that empties atria of residual blood
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describe ventricular systole
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atria relax, ventricles contract, pressure rises rapidly closing AVs opening sl valves, flows through pulmanary circuit
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describe isovolumetric relaxation
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early diastole, follows t-wave, ventricles relax, ventricular pressure decreases closing SL valves
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How do you find cardiac output
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CO=HRxSV
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How do you find stroke volume
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SV=EDV-ESV
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what is stroke volume
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volume of blood pumped out by one ventricle w/ each beat
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how does norepinephrine contribute to increasing contractility
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Ne bind B1 adrenergic receptors, and cause threshold to be reached more quickly and SA fires more rapidly
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what are the ionic basis of the fast response (phases)
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phase 0-genesis of the upstroke
phase 1-genesis of early repolarization phase 2-genesis of the plateau phase 3-genesis of final repolarization phase 4- restoration of ionic concentration |
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what is/happens during phase 0 during fast response
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Na+ enters myocyte via fast Na+ channels, goes from -90 to 0, continues in and Na+ gate starts to close at 20, completely closes at 30
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what is/happens in phase 1 of fast activation
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genesis of early repolarization, brief period of limited repolarization due to transient outward current (K+), activation of K+ channels cause brief efflux
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what is/happens in phase 2 of fast activation
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genesis of Plateau,Ca++ enters myocardial cell but slower, membrane potential plateau's as eflux of K+ is balanced by influx of Ca++
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what is/happens in phase 3 of fast activation
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genesis of final repolarization, when eflux of K+ is great than influx of Ca++
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what is/happens during phase 4 of fast activation
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restoration of ionic concentrations, by 3Na+ out for 1K+ in/ Ca++ eliminated by 3Na+ for 1Ca++/ Ca++ is eliminated via ATP driven Ca++ pump
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