The human circulatory system consists of three main components: the blood, the heart, and the blood vessels. The circulatory system's job is to transport substances around the body. The cells in the body require a constant input of oxygen and nutrients and a continuous removal of carbon dioxide and other wastes.
 |
| Note: This diagram is not to scale. The oxygenated blood is shown in red; deoxygenated blood is shown in blue. Oxygen gas is taken into the lungs when we inhale. The oxygen diffuses through the lung tissue into the blood stream, where is passes through the heart to then be dropped off to cells around the body. As the oxygen is being delivered to the cells, the cells release carbon dioxide gas and other wastes. The blood flows back, through the heart, to the lungs. The carbon dioxide diffuses into the lungs and is released when we exhale. |
The circulatory system has three main components:
Blood
There are four components of blood:
- Red Blood Cells - transport oxygen throughout the body, using hemoglobin.
- White Blood Cells - the infection fighters.
- Platelets - aid in blood clotting
- Plasma - liquid that carries the blood cells along.
Heart
There are three main components of the heart:
- Cardiac Muscle Tissue - makes the heart contract and moves blood around the body.
- Nerve Tissue - transmits signals to and from the central nervous system.
- Connective Tissue - contributes to structure and function.
 |
| Cardiac muscle tissue under the microscope. |
Blood Vessels
There are three types of blood vessels:
- Arteries - carry blood away from the heart.
- Veins - carry blood toward the heart.
- Capillaries - tiny blood vessels that allow substances to diffuse between blood and body fluids/tissues.
 |
| Artistic rendering of blood vessels. |
Time to make like the circulatory system and start pumping out some work.
