Characteristics of capillaries:
- Small diameter: Capillaries have a very small diameter, ranging from 5 to 10 micrometers. This allows them to fit into the narrow spaces between cells.
- Thin walls: Capillary walls are only one cell thick. This allows for the rapid exchange of oxygen and carbon dioxide between the blood and the tissues.
- Fenestrations: Capillary walls contain small pores called fenestrations. These fenestrations allow for the passage of small molecules, such as water, glucose, and amino acids, into and out of the blood.
- Glycocalyx: The inner surface of capillary walls is lined with a glycocalyx. The glycocalyx is a layer of carbohydrates that helps to regulate the passage of molecules into and out of the blood.
- Basement membrane: Capillaries are surrounded by a basement membrane. The basement membrane is a layer of connective tissue that provides structural support for the capillary.
Capillaries are essential for the proper functioning of the human body. They allow for the exchange of oxygen and carbon dioxide between the blood and the tissues, and they also transport nutrients and waste products.