What Does Blood Do in the Circulatory System?
Blood is the liquid pumped by the heart throughout the body. The cells are produced in the bone marrow.
The chief function of blood is to bring oxygen and nutrients to tissues in the body, and to carry away carbon-dioxide, lactic acid and other waste material. It also transports hormones and other substances between organs and body tissues.
Blood is made up of the following main components:
- Plasma - This is the fluid of blood. It is mostly water, with about 4% proteins including albumin, as well as antibodies, hormones and blood clotting factors.
- Red blood cells - These make up most of the blood cells. They contain a red protein pigment called hemoglobin which combines with oxygen so it can be carried around the body. They also contain the proteins which determine blood types.
- White blood cells - These are part of the immune system, and defend the body against infection.
- Platelets - These are sacks of blood clotting chemicals.
The Functions of Blood
White Blood Cell Chases Bacteria in Real Life
How Blood Clots
Did You Know ... ?
- Our red blood cells do not have a nucleus or organelles, which all cells have. So, according to the definition, they are actually not really cells!
- Most medical terms related to blood begin with hemo- or hemato- (or haemo- and haemato-) which comes from the Greek word haima which means blood.
- Blood makes up about 7% of our body weight, and over half of that 7% is plasma.
Our blood type (or blood group) is determined by substances on the surface of our red blood cells.
More by this Author
A simple explanation of how the gall bladder works and what it does in the human body.
How does the sense of touch work? Here is a simple explanation to help you understand how the body is able to feel. How does this one of the five senses work?
Traditionally we have five main senses. These are sight, smell, taste, hearing and touch. Find out about these five senses, as well as some surprising additional senses we don't usually hear about.