Chapter 15

THIRD EDITION

HUMAN PHYSIOLOGY AN INTEGRATED APPROACH Dee Unglaub Silverthorn, Ph.D.

Chapter 15 Blood Flow and the Control of Blood Pressure

PowerPoint® Lecture Slide Presentation by Dr. Howard D. Booth, Professor of Biology, Eastern Michigan University Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings

The Blood Vessels and the Cardiovascular System • Arteries: blood from heart • Strong & Elastic • Conduct blood to capillaries • Sphincters • Capillaries: exchange with cells • Veins • Return blood to heart • Valves Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings

Arteries

endothelium Smooth muscle cell layer adventitia Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings

Veins “Blood Reservoir” 70% of our blood volume is on the venous side.

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The Blood Vessels and the Cardiovascular System

Figure 15-1: Functional model of the cardiovascular system

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• ARTERIES • ARTERIOLES (pressure variability) • METARTERIOLES (pressure variability) • CAPILLARIES (microcirculation; low pressure)

• VENULES (microcirculation; low pressure) • VEINS

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Make Up of Blood Vessels: Arteries and Arterioles

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Figure 15-2: Blood vessels

Metarterioles

• Bypass capillaries • Large cells • Speed flow

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Figure 15-3: Metarterioles

Blood Pressure: Generated by Ventricular Contraction

• Pulsatile: surges in arteries • Elastic rebound evens & maintains pressure

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Blood Pressure: Generated by Ventricular Contraction

Figure 15-4: Elastic recoil in the arteries Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings

Blood Pressure (BP): Measurements

• "Blood pressure"

• Systolic over diastolic • About 120/80 mmHg • Sphygmomanometer

• "Estimate of pressure" • Korotkoff sounds

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More Blood Pressures: Pulse and Mean Arterial Pressures

Figure 15-5: Pressure throughout the systemic circulation Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings

More Blood Pressures: Pulse and Mean Arterial Pressures

• Pulse pressure is the strength of the pulse wave. • Pulse pressure = Systolic–Diastolic • Mean arterial pressure is an estimate of ventricular pressure. • Mean arterial pressure (MAP) = Diastolic + 1/3 pulse p

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Blood Pressure (BP): Measurements

Figure 15-7: Measurement of arterial blood pressure Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings

Arteriole Resistance: Control of Local Blood Flow • Myogenic auto regulation • Paracrines: • Active hyperemia • Reactive hyperemia • Sympathetic nerves – CNS • Not lecturing on it; but you are responsible for this information.

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Capillary Blood Flow: Greatest Total Cross Sectional Area

• Lowest Velocity • Hydrostatic pressure drops

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Figure 15-17: The velocity of flow depends on the total crosssectional area

Capillary Exchange:

• Filtration; leaves capillary • Absorption; enters capillary • Plasma (inside capillary) • Interstitial fluid or ECF (outside capillary) • Colloid osmotic pressure • Created by proteins in the plasma (constant) • Hydrostatic pressure- like holes in a garden hose. • Decreases from artery to venous side!!!

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Capillary Exchange: Colloidal Osmotic Pressure is Constant

Figure 15-18a: Fluid exchange at the capillary Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings

Net Out Flow Into ECF • Net filtration – net absorption = net out flow • About 2 L/day collected by lymph vessels

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Figure 15-18b: Fluid exchange at the capillary

Capillary Exchange: Hydrostatic Pressure Declines • High on arterial side – bulk flow out • Low on venous side – bulk flow in • Fenestrations &/or leaky joints speed exchange

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Figure 15-18a: Fluid exchange at the capillary

Lymphatic System: Structure and Roles (overview) • Lymphatic structures • Capillaries with valves • Lymph vessels • Lymph nodes & organs • Immune defense • Transport of fats • Collects excess ECF • Returns to plasma • Edema Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings

Lymphatic System: Structure and Roles (overview)

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Figure 15-19: The lymphatic system

Lymph Node; Immune function

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Edema; increase in hydrostatic pressure

Abnormal swelling

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Regulation of Blood Pressure

• Medullary cardiac control center

• Baroreceptor reflex • Carotid • Aortic

PLAY

Animation: Cardiovascular System: Blood Pressure Regulation

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Regulation of Blood Pressure

Figure 15-22: The baroreceptor reflex: the response to increased blood pressure Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings