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32 Cards in this Set
- Front
- Back
Vasodilation or vasoconstriction occurs mostly (and with great effect) in which blood vessels?
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arterioles
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Where is most blood found in the body?
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systemic circulation (specifically veins since they store blood)
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How is velocity of blood flow related to the cross sectional area of a vessel?
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Inversely proportional. V= (F/A). Greater cross sectional area (vasodilation) = slower flow
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What is the ideal systolic/diastolic pressure of the pulmonary artery?
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25/8 (averages to 16)
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What is the ideal systolic/diastolic pressure of the aorta?
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120/80
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Why is it important that capillary pressure doesn't rise above 17 mmHg?
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capillaries have pores. if the pressure rises too much, the hydrostatic force will cause leaking of fluid or particles out of the vessel (edema, exudate etc.)
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How do local tissues regulate blood flow with regard to tissue need?
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vasodilation and constriction
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How is blood flow related to resistance?
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inversely proportional; more resistance = less flow
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How is blood flow related to pressure difference?
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proportional; more pressure difference = more flow
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If the pressure at both ends of a blood vessel is 100 mmHg, what will the blood flow be in that vessel?
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no blood flow. there needs to be a pressure difference between the ends of the vessel for flow to occur
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Normal cardiac output is ....
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5 L/min
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2 mechanisms for measuring blood flow
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Electromagnetic Flowmeter or Ultrasound/Doppler Effect
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What is laminar flow of blood?
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the blood is unidirectional and faster in the center of the vessel due to less interaction/resistance form the vessel wall.
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What is turbulent flow of blood?
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blood is not laminar; more erratic and disorderly
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What is a parabolic velocity profile?
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shows laminar flow; flow is faster in the center of the vessel due to less interaction/resistance form the vessel wall.
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What is the Reynold's number?
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tells the likelihood of turbulence flow. R = ((velocity)(diameter)(density))/viscosity
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When pressure in an artery is 100 mmHg, what do those numbers and units mean?
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in that artery, there is enough pressure on the vessel wall to raise a column of mercury 100 mm high
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When pressure in an artery is 10 cm H2O, what do those numbers and units mean?
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in that artery, there is enough pressure on the vessel wall to raise a column of water 10 cm high
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Which circuit has more resistance? Systemic or pulmonary?
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Systemic has about 7x more resistance
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How is conductance related to resistance?
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inversely proportional. more resistance = less conductance
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What is conductance?
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how much flow occurs. inversely proportional to resistance
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How is conductance related to vessel diameter?
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conductance = diameter^4
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What is Poiseuille's Law stating in relation to blood flow?
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the closer flow is to the vessel wall, the slower it is due to resistance/interaction from the wall. this is how we get laminar flow
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Total Peripheral Resistance (in series) =
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R+R+R+R+R since they are in series (artery to capillary to vein)
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1/ Total Tissue Resistance (in parallel)=
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(1/R)+(1/R)+(1/R)+(1/R) since they are in parallel within tissues and organs
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Total Conductance in parallel =
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C+C+C+C+C in parallel (opposite of resistance since they are inversely proportional)
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Amputation of a limb has what effect on total peripheral resistance and conductance?
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since it is in parallel, resistance increases and conductance decreases
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Excess hematocrit (e.g. polycythemia) has what effect on blood flow?
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slower flow as blood is more viscous
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Major changes in BP don't usually effect the tissues blood supply. Why?
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tissues "auto-regulate". they are able to constrict/dilate to keep a constant supply of blood
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If BP was high in a certain tissue, what effect would occur within the tissue arterioles to auto-regulate the amount of blood flow?
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constriction. there is too much blood getting to the tissue, so it closes of vessels (increases resistance/constricts)
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Inhibition of sympathetics has what effect on vessel diameter?
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sympathetics constrict, so inhibition leads to dilation (lower BP, more flow)
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Excess of sympathetics has what effect on vessel diameter?
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sympathetics constrict = smaller diameter = higher BP = less flow
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