Capillaries

Capillaries are the smallest blood vessels in the body, with a diameter that is often smaller than a single red blood cell. They play a crucial role in the circulatory system, facilitating the exchange of oxygen, carbon dioxide, nutrients, and waste products between the blood and the surrounding tissues.

Structure of Capillaries

Capillaries are composed of a single layer of endothelial cells, which are thin and permeable, allowing for the exchange of substances. Their walls are so thin that oxygen and nutrients can easily pass through to nourish the surrounding cells, while waste products like carbon dioxide can move from the cells into the bloodstream for removal.

Function of Capillaries

The primary function of capillaries is to facilitate the exchange of substances between the blood and tissues. Oxygen and nutrients are delivered to the cells, while waste products like carbon dioxide are picked up and transported away for elimination. This exchange is essential for the proper functioning of the body's cells and organs.

Study Guide

1. What are capillaries?
2. Describe the structure of capillaries.
3. What is the primary function of capillaries?
4. How do capillaries facilitate the exchange of substances?
5. Why is the structure of capillaries important for their function?
6. Explain the role of capillaries in the circulatory system.

Understanding the structure and function of capillaries is crucial for comprehending the circulatory system and how the body maintains proper balance and function. Mastery of these concepts will provide a solid foundation for further studies in human biology and physiology.