Chapter 42.3, Problem 1CC

Summary Introduction

To explain: The reason behind low velocity of blood flow in capillaries.

Concept introduction:

The smallest arterioles break-up into a number of minute vessels called capillaries. Capillaries are the smallest blood vessels of the body, which connect the arterioles and venules. Walls of capillaries are composed of a thick layer of cell called as simple squamous epithelium or endothelium.

The absence of smooth muscles and connective tissue layers permits more rapid exchange of materials between the blood and the tissues. In human body, about 7 billion of capillaries are present enormously. Capillaries exhibits homologous structure to erythrocyte in diameter 7 µm.