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Physiology Final
Question | Answer |
---|---|
flow rate | ΔP/R |
factors that affect resistance to blood flow (3) | Viscosity of the blood - directly proportional Vessel length - remains constant in the body Vessel radius - resistance is inversely proportional to the 4th power of the radius |
Connective tissue in arteries contains abundance of these tissue types (2) | Collagen - tensile strength Elastin - elasticity |
Blood pressure depends on (2) | volume of blood contained within vessel compliance/distensibility of vessel walls |
During diastole, ventricular or atrial pressure falls to 0 mm Hg | Ventricular. The next cardiac contraction occurs and fills the arteries before all the blood drains off in the arteries |
Mean arterial pressure = | diastolic pressure + (1/3) pulse pressure 93 mm Hg at 120/80 |
Pressure of blood leaving arterioles and entering the capillaries | 37 mm Hg |
Vascular tone in arterioles is due to (2) | Arteriolar smooth muscle is tonic smooth muscle that has sufficient surface-membrane Ca2+ channels open at resting potential. (myogenic activity) Sympathetic fibers supplying most arterioles continually release norepinephrine which enhances vascular tone |
Vasoconstriction of Arterioles is caused by (7) | increased Myogenic activity Increased O2 Decreased CO2 Increased Endothelin Increased Sympathetic Stimulation Vasopressin; angiotensin II Cold |
Local metabolic changes that cause vasodilation of Arterioles (8) | Decreased O2 Increased CO2 (by-product of ox. phosphorylation) Increased acid (lactic & carbonic) Increased K+ Increased osmolarity Adenosine Prostaglandin |
Active Hyperemia | During increased metabolic activity the local [O2] decreases. Along with other local chemical changes, this causes local arteriolar dilation by triggering relaxation of local arteriolar smooth muscle -> increases blood flow to that area. |
Nitric oxide | Induces relaxation of arteriolar smooth muscle in vicinity causing local arteriolar vasodilation. Increases the concentration of cyclic GMP which leads to activation of an enzyme that reduces the phosphorylation of myosin |