Chapter 6: The Peripheral Vascular System

OBJECTIVES

The student understands the basic principles of cardiovascular transport and its role in maintaining homeostasis:

• Identifies the factors that determine transport of substances within the vascular system and those that determine diffusion across the capillary wall.

• Describes how capillary wall permeability to a solute is related to the size and lipid solubility of the solute.

• Lists the factors that influence transcapillary fluid movement and, given data, predicts the direction of transcapillary fluid movement.

• Describes the lymphatic vessel system and its role in preventing fluid accumulation in the interstitial space (i.e., edema).

The student understands the physical factors that regulate blood flow through and blood volume in the various components of the vasculature:

• Given data, calculates the vascular resistances of networks of vessels arranged in parallel and in series.

• Describes differences in the blood flow velocity in the various vascular segments and how these differences are related to their total cross-sectional area.

• Describes laminar and turbulent flow patterns and the origin of flow sounds in the cardiovascular system.

• Identifies the approximate percentage of the total blood volume that is contained in the various vascular segments in the systemic circulation.

• Defines peripheral venous pool and central venous pool.

• Describes the pressure changes that occur as blood flows through a vascular bed and relates them to the vascular resistance of the various vascular segments.

• States how the resistance of each consecutive vascular segment contributes to an organ’s overall vascular resistance and, given data, calculates the overall resistance.

• Defines total peripheral resistance (systemic vascular resistance) and states the relationship between it and the vascular resistance of each systemic organ.

• Defines vascular compliance and states how the volume–pressure curves for arteries and veins differ.

• Predicts what will happen to venous volume when venous smooth muscle contracts or when venous transmural pressure increases.

• Describes the role of arterial compliance in storing energy for blood circulation.

• Describes the auscultation technique for determining arterial systolic and diastolic pressures.

• Identifies the physical bases of the Korotkoff sounds.

• Indicates the relationship between arterial pressure, cardiac output, and total peripheral resistance and predicts how arterial pressure will be altered when cardiac output and/or total peripheral resistance changes.

• Given arterial systolic and diastolic pressures, estimates mean arterial pressure.

• Indicates the relationship between pulse pressure, stroke volume, and arterial compliance and predicts how pulse pressure will be changed by changes in stroke volume, or arterial compliance.

• Describes how arterial compliance changes with age and how this affects arterial pulse pressure.

INTRODUCTION

Recall from Chapter 1 that the primary job of the cardiovascular system is to maintain “homeostasis” within a body that contains billions of closely spaced individual cells. Homeostasis implies that each and every cell in the body is continually bathed in a local environment of constant composition that is optimal for cell function. In essence, the peripheral vascular system is a sophisticated irrigation system. Blood flow is continually delivering nutrients to and ...