s15 - Circulation Circulation Control of flow and pressure:...

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Unformatted text preview: Circulation Circulation Control of flow and pressure: Centralcardiac output Extrinsic control: Hormones & nerves Epinephrine, adrenal gland (adrenaline) Autonomic nervous control The cardiac cycle Medulla: Stimulatory vs. Inhibitory Centers Relative output determines rate: Accel. Vs. Brake Aorta and carotid body chemoreceptors & baroreceptors Hypercapnia/Hypoxia stimulates Stimulatory Center Increase in COincreased blood flow to lungs and tissues Increased excretion of CO 2 and O 2 uptake Increase in blood pressure (baroreceptor) stimulates the Inhib. Ctr. and inhibits the Stim. Ctr. Decrease in CO and, therefore, blood pressure Decrease in blood pressure has opposite effect Circulation Circulation Control of flow and pressure: Centralcardiac output Peripheralvascular resistance Circulation Circulation Control of flow and pressure: Centralcardiac output Peripheralvascular resistance Small changes make a big difference: R ~ 1/r 4 Circulation Circulation Control of flow and pressure: Centralcardiac output Peripheralvascular resistance Small changes make a big difference: R ~ 1/r 4 r = 1 vs. r = 2: 1/1 vs. 1/16 = 1/16th r = 1 vs. r = 0.5: 1/1 vs. 1/0.0625 = 16X Circulation Circulation Control of flow and pressure: Centralcardiac output Peripheralvascular resistance Small changes make a big difference: R ~ 1/r 4 Most vessels can change diameterarterioles major but veins can also constrict and dilate Circulation Circulation Control of flow and pressure: Centralcardiac output Peripheralvascular resistance Small changes make a big difference: R ~ 1/r 4 Most vessels can change diameterarterioles major capillaries are exception Circulation Circulation Control of flow and pressure: Centralcardiac output Peripheralvascular resistance Small changes make a big difference: R ~ 1/r 4 Most vessels can change diameterarterioles major capillaries are exception Nervous control: Circulation Circulation Control of flow and pressure: Centralcardiac output Peripheralvascular resistance Small changes make a big difference: R ~ 1/r 4 Most vessels can change diameterarterioles major capillaries are exception Nervous control: vasomotor center in medulla Circulation Circulation Control of flow and pressure: Centralcardiac output Peripheralvascular resistance Small changes make a big difference: R ~ 1/r 4 Most vessels can change diameterarterioles major capillaries are exception Nervous control: vasomotor center in medulla Vasodilatory vs. vasoconstrictor ctrs. Circulation Circulation Control of flow and pressure: Centralcardiac output Peripheralvascular resistance...
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This note was uploaded on 02/10/2011 for the course BSC 2011 taught by Professor Haas during the Spring '08 term at University of Florida.

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s15 - Circulation Circulation Control of flow and pressure:...

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