Chapter15 - The Vascular System

Copyright © 2012 F.A. Davis Company

Understanding Anatomy & PhysiologyUnderstanding Anatomy & PhysiologyA Visual, Interactive ApproachA Visual, Interactive Approach

Chapter 15

The Vascular SystemThe Vascular System



Types of blood vesselsTypes of blood vessels

ArteriesArteries: Carry blood away from the heart

VeinsVeins: Return blood to the heart CapillariesCapillaries: Connect the smallest

arteries to the smallest veins



Blood vessel layersBlood vessel layers

Tunica intima

Tunica media

Tunica externa



Categories of arteriesCategories of arteries

Conducting arteries Conducting arteries (elastic arteries)

Distributing arteries Distributing arteries (muscular arteries)

ArteriolesArterioles (resistance vessels)



VeinsVeins Become smaller as they lead away

from the heart Have thinner walls than arteries Have a great ability to stretch Can constrict extensively



Categories of veinsCategories of veins

VenulesVenules Medium-sized veinsMedium-sized veins Large veinsLarge veins



CapillariesCapillaries

Are the exchange vessels Have extremely thin walls Have very small diameters



Veins are called capacitance vessels because:

A.they can constrict extensively.B.they can stretch.C.they convey blood back to the heart.D.they contain one-way valves.



Correct answer: B

Rationale: The ability of veins to stretch gives them a great capacity for storing blood. From this characteristic comes the name capacitance vessels.



Capillary organizationCapillary organization

Exercise Rest



Capillary exchangeCapillary exchange Walls allow for two-way exchange. Mechanisms of exchange include

diffusion, filtration, and osmosis.



DiffusionDiffusion



FiltrationFiltration



Colloid osmotic pressureColloid osmotic pressure

View animation of mechanisms of capillary exchange



Capillaries release oxygen and take up carbon dioxide from surrounding tissues through the process of:

A.osmosis.B.filtration.C.diffusion.D.colloid osmotic pressure.



Correct answer: C

Rationale: Diffusion is the most important mechanism of capillary exchange. Substances move from areas of greater to lesser concentration.



Pulmonary circulationPulmonary circulation

View animation on pulmonary circulation



Systemic circulationSystemic circulation

Ascending aortaAortic arch

Descending aorta



PulsesPulses



Principal arteriesPrincipal arteries

Subclavian artery

Axillary artery

Brachial artery

Radial artery

Thoracic aorta

Celiac trunk

Renal artery

Superior mesenteric artery

Inferior mesenteric artery

Common iliac artery

External iliac artery

Internal iliac artery Femoral artery

Popliteal artery

Anterior tibial artery

Posterior tibial artery

Dorsalis pedis artery



Arteries of head and neckArteries of head and neck

Vertebral artery



Circle of WillisCircle of Willis



Principal veinsPrincipal veins

Internal jugular vein

Cephalic vein

Medial cubital vein

Popliteal veinGreat saphenous vein

Hepatic vein



Veins of the head and neckVeins of the head and neck

Internal jugular vein

External jugular vein

Vertebral vein



Hepatic Hepatic portal portal circulationcirculation

View animation of hepatic-portal circulation



Portal systems allow blood to:

A.pass through two capillary networks before returning to the heart.B.pass through one capillary network before returning to the heart.C.bypass all capillary networks and return to the vena cava.D.shunt blood from one vein to another.



Correct answer: A

Rationale: Blood normally flows through one capillary network before returning to the heart. In portal systems, which occur in the kidneys and liver, blood flows through two networks of capillaries.



Principles of circulationPrinciples of circulation



Factors affecting blood Factors affecting blood pressurepressure

Cardiac output ↑CO = ↑BP↓CO = ↓BP

Blood volume ↓Volume = ↓ BP↑Volume = ↑ BP

Resistance ↑ Resistance = ↓Flow and ↑Pressure↓ Resistance = ↑Flow and ↓ Pressure



Peripheral resistancePeripheral resistance Resistance to flow results from

friction of blood against walls of vessels.

Amount of friction depends upon: Blood viscosity Vessel diameter



VasoconstrictionVasoconstriction



VasodilationVasodilation



Blood velocityBlood velocity



Which condition would you expect to accompany atherosclerosis, a disorder in which arteries lose elasticity and fatty material builds up inside the vessels?

A.Irregular heartbeatB.Low blood pressureC.Increased blood viscosityD.High blood pressure



Correct answer: D

Rationale:The accumulation of fatty material narrows vessel diameter, leading to higher blood pressure. A loss of arterial elasticity prevents arteries from expanding with each beat of the heart, which also contributes to higher blood pressure.



Neural regulation of blood Neural regulation of blood pressurepressure

↑BP→ Parasympathetic impulses→ Vasodilation→↑BP

↓BP→ Sympathetic impulses→ Vasoconstriction→↑ BP

View animation of neural regulation of blood pressure (baroreceptors)



Hormonal regulation of blood Hormonal regulation of blood pressurepressure

A number of hormones raise blood pressure

Atrial natriuretic peptide (ANP) causes blood pressure to fall



Venous returnVenous returnContracted skeletal musclesContracted skeletal muscles Relaxed skeletal musclesRelaxed skeletal muscles



Respiratory pumpRespiratory pump



When blood pressure suddenly rises, which structure sends out parasympathetic impulses?

A.The medulla B.BaroreceptorsC.Aortic archD.Atria



Correct answer: A

Rationale: Baroreceptors in the aortic arch detect changes and send signals to the medulla. The atria release the hormone atrial natriuretic peptide in response to high blood pressure.

Health & Medicine

Chapter15 - The Vascular System