Capillaries

Capillaries are small blood vessels that exchange nutrients, oxygen, and waste products between blood and tissues. They're part of the microcirculation system, along with arterioles and venules. Capillaries have thin walls made up of a single layer of endothelial cells, enabling efficient substance exchange.

Pericytes

Pericytes are specialized cells located in the walls of capillaries. Pericytes regulate blood vessel diameter, blood flow, and vascular permeability. They also provide structural support to the blood vessel walls and have been shown to contribute to the formation of scar tissue and the growth of new blood vessels in response to injury or disease.

Red Blood Cells

Red blood cells, also known as erythrocytes, are the most common type of blood cell in the human body. They are responsible for carrying oxygen from the lungs to the body's tissues and carrying carbon dioxide, a waste product, from the tissues back to the lungs to be exhaled.