Chapter 21, Problem 21.1.8AYLO

Summary Introduction

To analyze:

The distinction between continuous capillaries, fenestrated capillaries and sinusoids.

Introduction:

Materials such as food, waste and hormones must move through the walls of the vessels within the blood and the tissue fluids for any reason. The wall is too dense for sufficient movement of chemicals within the bloodstream and tissue fluid in almost all the larger vessels. The capillaries of the blood consist only of a basal lamina and an endothelium. Their walls are as thin a micrometer as 0.2 to 0.4. They average at the proximal end around 5 micrometers in diameter, widen at the distal end to around 9 micrometers, and often branch off along the way.