What role do capillaries play in the overall picture of circulation? Every single cell in the body needs oxygen and nutrition to perform their specific job. Without these two things, the cell simply dies.  The needed nutrients and oxygen are delivered to the cell in the body through blood circulation. These vital ingredients then travel through the wall of the capillaries and into the interstitial fluid. These feeds the body tissue.

Capillaries are the smallest blood vessels in the human body.  They are so tiny they can only be seen with a microscope. Typically the walls of capillaries are only one or two cells thick. They are so narrow that blood cells actually wait in line to pass through them.

There are capillaries all throughout the circulatory system and there are different kinds because they have different jobs. One of the “jobs” of capillaries is to help the body control temperature. When the body is exercising the temperature begins to heat up, the blood gets warmer. To help get rid of that excess heat the blood is quickly released by the capillaries. You will recognize what is happening because there will be a red flush to the skin. Those are your capillaries at work.

Capillaries are also responsible to remove waste at a cellular level.

The capillaries in liver look very much like a coiled snake. They make loops back and forth throughout the liver tissue. The job in the liver is to remove all the waste and toxins from the blood.

The capillaries found in the kidneys have many microscopic holes. They need these holes so substances can pass through and excrete waste.

The brain capillaries are very tight. The tissue in the brain is very delicate and fragile and require that not a a lot of transfer take place in the capillaries.

Substances pass through capillary walls by osmosis, diffusion and filtration.

Fluid movement through the capillary walls happens with a combination of  osmotic pressures and hydrostatic pressures.

Gasses move through diffusion. Gases go naturally from areas of greater concentration to areas of lesser concentration. So oxygen diffuses from the blood into the systemic capillaries to the tissue fluid. Carbon dioxide diffuses from tissue fluid to the capillaries to travel to the lungs to be expelled.

Sometimes there are abnormal accumulations of interstitial fluid. This is called edema. Things that may lead to edema may be an increase in the capillary blood pressure, a decrease in the number of plasma proteins and an increase in the permeability of the capillary so the protein can actually leak out.

These tiny little capillaries need to be healthy to keep the entire body running in top condition.

There are many capillaries in the body. It is estimated that if all the capillaries in the body were to be placed end to end, they would go completely around the earth’s equator 2.5 times. The body is truly amazing.