Chapter 19: Functions of the Blood Vessels Chapter 19: Functions of the Blood Vessels.

TheHuman Bodyin Healthand Illness

Barbara Herlihy

Chapter 19:Functions of the Blood

Vessels

Copyright © 2007 by Saunders, an imprint of Elsevier Inc.All rights reserved.

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Lesson 19.1 Objectives• Explain how the blood vessels act as

a delivery system.• Describe the factors that determine

blood pressure.• Explain the baroreceptor reflex.


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The Blood Vessels Deliver• Functions of blood vessels:

1. Act as a delivery system2. Regulate blood pressure3. Engage in the exchange of nutrients and

waste between the capillaries and cells4. Redistribute blood in response to changing

body needs5. Help regulate body temperature


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The Blood Vessels Deliver (cont’d.)

• “5 Cool Ps” of occlusive arterial disease:– Pain– Pulselessness– Pallor– Paresthesia– Paralysis– Coolness


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Blood Vessels RegulateBlood Pressure• Blood pressure: force of blood presses

against the walls of the blood vessels• Systolic pressure: pressure in the arteries at

the peak of ventricular contraction (systole)• Diastolic pressure: pressure in the large

arteries when the ventricles of the heart are relaxing (diastole)

• Pulse pressure: difference between systolic and diastolic pressure


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Blood Vessels RegulateBlood Pressure (cont’d.) • Normal range: 100 to 140 mm Hg

(systolic) and 60 to 90 mm Hg (diastolic) for adult males

• Hypertension: chronic elevation of blood pressure

• Korotkoff sounds: caused by blood flow through an artery


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Blood Vessels Regulate Blood Pressure (cont’d.)


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Skeletal muscle pump.


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Blood Vessels Regulate Blood Pressure (cont’d.) • Respiratory pump: effect of respiratory

activity on venous blood flow• Venoconstriction: constriction of the veins

pushes additional blood out of the veins toward the heart


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Relationship between pressure and force.


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Blood Vessels Regulate Blood Pressure (cont’d.) • Vasodilation: muscles relax and the

openings of the arterioles increase; resistance decreases in the blood vessels

• Vasoconstriction: muscles contract and the openings of the arterioles become smaller; resistance increases in the blood vessels


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Blood Vessels Regulate Blood Pressure (cont’d.) • Blood pressure = cardiac output ×

vascular resistance • Cardiac output: amount of blood pumped

by the heart each minute• Vasopressors: substances that cause

vasoconstriction and elevate blood pressure


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Blood Vessels Regulate Blood Pressure (cont’d.) • Rapidly acting mechanisms for blood

pressure regulation:– Baroreceptor reflex– Sympathetic nervous system stimulation– Parasympathetic nervous system stimulation


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Baroreceptor reflex.


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Blood Vessels Regulate Blood Pressure (cont’d.) • Baroreceptor reflex structures: receptors,

sensory nerves, medulla oblongata, and motor nerves

• Baroreceptors: pressure receptors located in the walls of the aortic arch and carotid sinus


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Blood Vessels Regulate Blood Pressure (cont’d.) • Slower-acting mechanisms for blood

pressure regulation:– Renin-angiotensin-aldosterone mechanism– Antidiuretic hormone (ADH)– Atrial natriuretic peptide (ANP)– Brain natriuretic peptide (BNP)


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Lesson 19.2 Objectives• Describe the factors that determine

capillary exchange.• Describe mechanisms of edema formation.• Explain how the blood vessels respond to

changing body needs.• Describe the role of the blood vessels in

the regulation of body temperature.


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Blood Vessels Act as Exchange Vessels


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Blood Vessels Act as Exchange Vessels (cont’d.)

• Capillaries as exchange vessels:– Thin capillary walls– Millions of capillaries– Slow velocity of blood flow


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• Capillary exchange processes:– Diffusion: substance moves downhill from an

area of high concentration to an area of low concentration

– Filtration-osmosis: outward and inward movement of water and dissolved substances •Oncotic pressure: created by plasma proteins

to pull the water from the interstitium into the capillary

•Edema: excess fluid collection in the interstitium


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• Mechanisms of edema formation:– Heart failure– Severe burn– Kidney disease– Blocked lymphatic drainage


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Blood Vessels Distribute Blood FlowDistribution of blood flow at rest and exercise.


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Blood Vessels Distribute Blood Flow (cont’d.)

• Distribution of blood flow:– Vasodilation– Vasoconstriction


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Blood Vessels Regulate Body Temperature• Role of blood vessels:

– Dissipate heat– Conserve heat

Chapter 19: Functions of the Blood Vessels Chapter 19: Functions of the Blood Vessels.

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Transcript of Chapter 19: Functions of the Blood Vessels Chapter 19: Functions of the Blood Vessels.