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67 Cards in this Set
- Front
- Back
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What separates the right heart and left heart in terms of capillary beds?
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Pulmonary circulation
(capillary beds for gas exchange) |
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Are arteries high or low pressure systems?
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high
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What type of innervation do arteries receive?
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dense sympathetic innervation
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What are the smallest branches of the arterial system?
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Arterioles
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What is the major resistance vessels of the circulatory system?
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arterioles
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What type of muscle at what thickness do arterioles have?
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Thick smooth muscle
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What is the function of arterioles?
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To control the flow of blood into capillary beds.
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Where is the largest pressure drop in the circulatory system?
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Arterioles
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What is basal tone?
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Partial contraction of vessels under normal conditions.
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How to arterioles control blood flow?
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through vasoconstriction and vasodilation
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What is role of basal tone?
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To allow a vessel to dilate and constrict from an at rest position
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What causes basal tone?
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intrinsic and local factors
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What type of vessels have no smooth muscle?
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capillaries
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What are the major exchange vessels?
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capillaries
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What vessels have the largest total cross-sectional area?
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capillaries
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What vessels have the lowest flow velocity?
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capillaries
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What vessels collect blood from capillaries?
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venules
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What vessels are capable of exchange?
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capillaries and venules
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How is total cross-sectional area related to the velocity of blood flow?
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Greater CSA = Decreased V
Lesser CSA = Increased V |
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What is the function of veins?
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To return blood to the right heart
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What vessels have the largest capacitance?
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Veins
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Where is the largest reservoir of blood stored?
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Veins
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In a resting individual, how much blood can be found in the lungs, heart, or arteries?
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~10%
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What percentage of blood can be found in the systemic veins?
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~60-70%
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What has larger cross-sectional area: small veins or small arteries?
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Small veins (80 vs 20 cm2)
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What are the units for cross-sectional area of vessels?
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cm2
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What has larger cross-sectional area: arterioles or small veins?
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Small veins (80 vs 40 cm2)
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How is the velocity of blood calculated?
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V = Q/A
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What is the rough value of mean arterial pressure?
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100 mm Hg
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What vessels have the lowest systemic pressure?
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Vena cava and pulmonary veins
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What factors allow capillaries to have continuous flow throughout the cardiac cycle?
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Compliance of arterial vessel walls
Resistance as vessel diameter gets smaller |
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What disease is characterized by pulsatile flow through capillaries?
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Graves' disease
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What disease is associated with arteriolar vasodilation and reduced resistance?
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Graves' disease
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When, during the cardiac cycle, is the pressure above the mean arterial pressure?
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During systole
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What is the pulse pressure?
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Systolic pressure - Diastolic pressure
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Is the mean arterial pressure greater or lesser than the diastolic pressure?
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Greater
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How is mean arterial pressure calculated?
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1/3 systolic pressure + 2/3 diastolic pressure
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What is blood flow?
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The quantity of blood that passes a given point in a given period of time
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What is the equation for blood flow?
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Q = dP/R (Ohm's law)
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What is the effect of total pressure on flow (Q)?
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Nothing. Driving force is a change in pressure between two points.
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What is compliance?
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The total quantity of blood that can be stored in a given portion of circulation.
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How is compliance measured?
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C = dV/dP
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What vessels have the highest compliance? Why?
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veins: largest volume and lowest pressure
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What happens to vascular compliance with age?
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Arteries become stiff and less distensible, causing greater pressure.
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What is the difference between atherosclerosis and arteriosclerosis?
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Athero: plaque
Arterio: Collagen in the vessel wall. |
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What happens as a result of sclerosis?
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Decrease in the elasticity of the artery walls.
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How does arterial pressure effect flow?
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Increases flow because there is more driving force pushing the blood and distends vessel walls which decreases resistance.
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What factors effect the resistance in circulation? (3)
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Blood viscosity
Vessel length Radius of the vessel |
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When describing parallel resistance, what is the total resistance as related to the resistance of any one vessel?
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Total resistance is less than any one vessel.
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What is the pressure change in arteries that run in parallel?
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no change, all have the same pressure.
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What vessels have the greatest contribution to the amount of resistance in series?
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arterioles
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What is the pressure change in vessels that run in series?
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Decreasing pressure
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What is total peripheral resistance?
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the amount of resistance that blood feels as it passes from arterioles to venules.
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How does viscosity change resistance?
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Directly proportional
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What happens with increased hematocrit?
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Decreased flow due to increased resistance.
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What causes viscosity at low hematocrits (greater than plasma and water)?
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Stickiness of RBC
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What causes viscosity at high hematocrits?
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RBC deformation
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During laminar flow, were is velocity maximal?
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At the central axis
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What is the distribution of velocity in laminar flow?
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Parabolic
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What is the effect of axial streaming on RBC?
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Decreases viscosity
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What is Reynolds number used to determine?
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Laminar or turbulent flow
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What variables effect Reynolds number?
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Mean velocity
Vessel diameter Fluid density Fluid viscosity |
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Blood flow is laminar with what value for Reynolds number?
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Values below 2000
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How does velocity effect Reynolds number?
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directly proportional
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How does tube diameter effect Reynolds number?
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directly proportional
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How does fluid density effect Reynolds number?
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Directly proportional
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What do you need for laminar flow?
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Low velocity
Small diameter vessel Low density fluid High viscosity |
