Anatomy Physiology SIXTH EDITION Chapter 21 part 1

Anatomy & Physiology SIXTH EDITION Chapter 21, part 1 Blood Vessels and Circulation Power. Point® Lecture Slide Presentation prepared by Dr. Kathleen A. Ireland, Biology Instructor, Seabury Hall, Maui, Hawaii Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Frederic H. Martini Fundamentals of

Learning Objectives • Distinguish among the types of blood vessels. • Describe fluid and dissolved material transport into and out of the cardiovascular system. • Describe the factors that influence blood pressure and blood pressure regulation. • Discuss the mechanisms involved in the movement of fluids between capillaries and interstitial spaces. Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Learning Objectives • Describe how blood flow and pressure in tissues is regulated. • Identify the principle blood vessels of each circuit and the areas they serve. • Describe fetal circulation patterns and the changes that occur in these patterns at birth and during aging. Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

SECTION 21 -1 The Anatomy of Blood Vessels Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Structure of vessel walls • Walls of arteries and veins contain three distinct layers • Tunic intima • Tunica media • Tunica externa Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Figure 21. 1 A Comparison of a Typical Artery and a Typical Vein Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 21. 1

Differences between arteries and veins • Compared to veins, arteries • Have thicker walls • Have more smooth muscle and elastic fibers • Are more resilient Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Arteries • Undergo changes in diameter • Vasoconstriction – decreases the size of the lumen • Vasodilation – increases the size of the lumen • Classified as either elastic (conducting) or muscular (distribution) • Small arteries (internal diameter of 30 um or less) are called arterioles Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Capillaries • An endothelial tube inside a basal lamina • These vessels • Form networks • Surround muscle fibers • Radiate through connective tissue • Weave throughout active tissues • Capillaries have two basic structures • Continuous • Fenestrated • Flattened fenestrated capillaries = sinusoids Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Figure 21. 2 Histological Structure of Blood Vessels Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 21. 2

Figure 21. 4 Capillary Structure Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 21. 4

Capillary Beds • An interconnected network of vessels consisting of • Collateral arteries feeding an arteriole • Metarterioles • Arteriovenous anastomoses • Capillaries • Venules Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Figure 21. 5 The Organization of a Capillary Bed Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 21. 5 a, b

Veins • Collect blood from all tissues and organs and return it to the heart • Are classified according to size • Venules • Medium-sized veins • Large veins Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Venous Valves • Venules and medium-sized veins contain valves • Prevent backflow of blood Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Figure 21. 6 The Function of Valves in the Venous System Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 21. 6

Distribution of blood • Total blood volume is unevenly distributed • Venoconstriction maintains blood volume • Veins are capacitance vessels • Capacitance = relationship between blood volume and pressure PLAY Animation: Anatomy Review: Blood Vessel Structure and Function Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Figure 21. 7 The Distribution of Blood in the Cardiovascular System Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 21. 7

SECTION 21 -2 Cardiovascular Physiology Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Circulatory Pressure • Circulatory pressure is divided into three components • Blood pressure (BP) • Capillary hydrostatic pressure (CHP) • Venous pressure Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Figure 21. 8 An Overview of Cardiovascular Physiology Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 21. 8

Resistance (R) • Resistance of the cardiovascular system opposes the movement of blood • For blood to flow, the pressure gradient must overcome total peripheral resistance • Peripheral resistance (PR) is the resistance of the arterial system Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Overview of Cardiovascular Pressures • Factors involved in cardiovascular pressures include • Vessel diameter • Cross-sectional area of vessels • Blood pressure • Blood viscosity Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings

Figure 21. 9 Relationships among Vessel Diameter, Cross-sectional Area, Blood Pressure, and Blood Viscosity Copyright © 2004 Pearson Education, Inc. , publishing as Benjamin Cummings Figure 21. 9