Term
| Where does blood entering the (R) atria come from? (L) atria? |
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Definition
| (R) - vena cava and coronary sinus. (L) - pulm. veins |
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Term
| What is the average CO from the (L) vent? |
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Definition
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Term
| In the steady states what is the CO of the (L) heart in relation to the CO of the (R) heart? |
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Definition
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Term
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Definition
| Blood flow to the atria from the veins (CO = VR in steady state) |
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Term
| Describe the path of blood flow starting with arteries. |
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Definition
| Art. - arterioles - capillaries - venules - veins |
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Term
| What makes up the arterial walls? |
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Definition
| Smooth mus., elastic, and connective tissue. |
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Term
| What is the fxn of smooth mus. in vasculature? |
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Definition
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Term
| The blood volume in the art. is often referred to as _________ volume. Why? |
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Definition
| Stressed - it is under high pressure |
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Term
| Why do the lg. art. have a substantial amt. of elastic tissue? |
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Definition
| Prevents BP from falling too much (helps maintain pressure) |
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Term
| Which vessels are the site of highest resistance to blood flow? Why? |
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Definition
| arterioles - extensive smooth mus. |
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Term
| What innervates the smooth mus. of skin and splanchnic arterioles? What receptor is activated and what happens when its activated? |
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Definition
| Sympathetic - alpha1 adrenergic - vasoconstriction |
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Term
| What receptor is activated in sympathetic innervation of smooth mus. of skeletal muscle arterioles? What happens when its activated? |
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Definition
| beta2 adrenergic - vasodilation |
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Term
| What makes up the capillary wall? |
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Definition
| single-layer endothelial cells |
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Term
| What occurs at the capillary level? What substances are able to pass through the capillary wall? |
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Definition
| Site of exchange b/t tissues and blood. Lipid-soluble sub. and water (O2, CO2, steroid hormone) |
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Term
| Can water-soluble substances pass through the capillary wall? |
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Definition
| Through clefts b/t cells or through fenestrations in the cell membrane |
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Term
| The lower proportion of _________ tissue in veins results in their very large ___________. |
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Definition
| elastic tissue, capacitance (compliance) |
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Term
| Similar to arterioles, veins are innervated by ____________ nerve fibers which cause _________________. |
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Definition
| sympathetic, venoconstriction |
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Term
| What is the blood volume in the veins is often referred to as? Why? |
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Definition
| Unstressed volume - not under pressure |
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Term
| Why do the veins contain most of the blood in the CV system? |
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Definition
| Due to their large capacitance |
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Term
| What is the formula for velocity of blood flow? |
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Definition
| V = Q/A (V = velocity, Q = flow in ml/min, A = cross sectional area) |
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Term
| At what level of the CV system is velocity the fastest? Slowest? |
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Definition
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Term
| What is the equation for blood flow through a vessel? |
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Definition
| Q = change P/R (P pressure difference, R resistance) |
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Term
| What is the major mechanism for changing blood flow? |
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Definition
| Changing the resistance of blood vessels |
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Term
| What is TPR? What is the formula? |
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Definition
| Total peripheral resistance - resistance of the entire vascular resistance. R = Change P/Q (Q=CO) |
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Term
| What is the Poiseuille equation? |
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Definition
| The relationship b/t resistance, blood vessel radius, and blood viscosity. R=8nl/nr^4 |
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Term
| Viscosity is _________ proportional to resistance. Length is _________ proportional to resistance. |
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Definition
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Term
| How is resistance affected if the vessel diameter is halved? |
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Definition
| resistance increases by 16 |
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Term
| The hematocrit value is directly proprtional tol what? |
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Definition
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Term
| List the vessels in order from decreasing resistance and pressure through the CV system. Does blood flow (Q) change through the levels? |
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Definition
| Art. - arterioles - capillary - venule - vein. Q stays the same. |
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Term
| Where does the greatest drop in pressure occur? |
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Definition
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Term
| In a parallel arrangement adding a resistance to the circuit causes total resistance to ____________ |
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Definition
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Term
| What happens to the total R if one of the arteries becomes totally occluded? |
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Definition
| Resistance becomes infinity |
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Term
| Describe ideal blood flow in the CV system. |
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Definition
| Laminar - parabolic profile in which the velocity is highest in the center of the vessel and lowest near the walls where blood adheres |
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Term
| What causes turbulent blood flow? What is it heard as on auscultation? |
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Definition
| Occurs at the valves or near a clot (atherosclerosis) because more pressure is required to drive the blood. Audible as murmurs. |
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Term
| What is Reynold's number? |
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Definition
| used to predict turbulence |
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Term
| Name the major variables that affect reynolds number. |
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Definition
| Viscosity, velocity and vessel diameter |
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Term
| Give an example of how viscosity affects turbulence. |
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Definition
| Decreasing hematocrit (anemia, high CO) increases chances of turbulence |
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Term
| How does velocity and vessel diameter affect turbulence? what has a greater impact on turbulence? |
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Definition
| Narrowing of blood vessel (thrombus) increases velocity and t/f increases likelihood of turbulence. Velocity. |
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Term
| What does capacitance of a blood vessel describe? |
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Definition
| the volume that a blood vessel can hold at a given pressure |
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Term
| Why are aging art. less compliant? How does this affect BP? |
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Definition
| They harden with age so BP increases in the elderly |
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Term
| What is the formula for capacitance? |
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Definition
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Term
| If the compliance of veins decreases d/t venoconstriction, how does it affect the blood volume? |
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Definition
| Shifts from unstressed (vein) to stressed volume (art.) |
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Term
| How is (L) atrial pressure measured? |
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Definition
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Term
| Why do pressures drop as blood flows through the systemic and pulmonary system? |
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Definition
| BP decreases as blood moves through the system d/t frictional energy |
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Term
| How does resistance differ between the systemic and pulmonary circulation? |
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Definition
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Term
| Where in the CV system mean BP the highest? Why? |
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Definition
| Aorta - lg. blood volume and low compliance |
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Term
| How is high pressure maintained in the lg. arteries? |
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Definition
| Elastic recoil of art. walls prevents frictional energy loss |
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Term
| Why does the greatest drop of pressure occur at the level of arterioles? |
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Definition
| high resistance to blood flow (vasoconstriction from smooth mus. innervated by symp. NS) |
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Term
| Where is the lowest pressure? Why? |
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Definition
| Veins and venules - high compliance |
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Term
| What is diastolic pressure? Is it the lowest or highest arterial pressure? |
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Definition
| (L) ventricular relaxation - lowest |
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Term
| What is systolic pressure? |
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Definition
| (L) vent. contraction - highest art. pressure |
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Term
| What is pulse pressure? What is it a reflection of? |
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Definition
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Term
| How is mean arterial pressure calculated? |
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Definition
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Term
| What is stroke volume? What is the volume typ? |
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Definition
| the amount of blood the vent. ejects in 1 contraction - ~70mL |
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Term
| What is the dicrotic notch? |
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Definition
| a very brief drop in BP that occurs b/c the aortic valve is closing and blood flow is briefly retrograde |
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Term
| Why is pulse pressure absent when blood enters the arterioles? |
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Definition
| Because resistance increases (diameter decreases) |
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Term
| How does arteriosclerosis affect arterial pressure? |
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Definition
| Plaques decrease blood vessel diameter and compliance causing increased systolic, mean and pulse pressure |
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Term
| How does aortic stenosis affect arterial pressure? |
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Definition
| Decreases SV, systolic, mean, and pulse pressure b/c less blood is able to be pumped into the aorta |
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Term
| A 60yo man has a BP of 180/100, HR of 78, and a PP of 80. His cholesterol is in the upper 25th %. A decrease in what is the most likely cause for the high PP? |
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Definition
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Term
| Which part of the CV system has the highest compliance? |
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Definition
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Term
| An increase in what would tend to decrease PP? |
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Definition
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Term
| A 35yo woman has a mean BP of 105 and HR of 74. The pt has aortic stenosis. How changes would be expected in PP, SV, and SBP? |
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Definition
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Term
| Blood flow through a blood vessel occurs at 10ml/min under pressure gradient of 100. What would the flow through the vessel be after the diameter of the vessel was increased 2X? |
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Definition
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Term
| Where in the CV system is blood flow the slowest? |
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Definition
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