Circulatory System

The Most Important System!

Introduction to the Circulatory System

The circulatory system is one of the most important systems of the human body. It is the system that delivers essential nutrients to the tissues and organs, and most importantly, it is the system that pumps blood throughout the whole body and keeps you alive.


The anatomy of the Circulatory System consists completely of the heart, the veins, and the arteries.

The Heart

The heart is one of the most important organs in the body, not just the circulatory system. The right side of the body deals with un-oxygenated blood. The right atrium is where the veins come into the heart. After passing through this chamber the blood goes to the right ventricle. After that the blood goes to the lungs by the pulmonary artery, the only artery that carries un-oxygenated blood. In the veins inside the lungs the blood gives up the CO2 and picks up oxygen. After that the pulmonary vein brings the oxygenated blood to the LEFT atrium. The blood flows through a valve from the left atrium to the left ventricle. After that the blood is pumped from the heart in the aorta to the rest of the body. Valves separate the atrium and the ventricle, and keep the blood from flowing backwards

The Veins and Arteries

The arteries get smaller away from the heart, from arteries to arterioles, to capillaries. The capillaries are the point of exchange of oxygen and CO2 in the tissues. Then the blood goes through tiny veins called venules to the larger veins. The blood flows slower coming to the heart because the veins don't have muscle to push it along, like the arteries. Near the heart the blood goes through veins into the heart. The process of the heart is described in the paragraph above. When the blood comes out of the left side of the heart, into the body, it starts the process again.


There are many functions for the Circulatory System.


The Circulatory System circulates blood throughout the body. The blood is distributed to the tissues to provide them with nutrients and oxygen. Also it removes waste from the tissues.


The white blood cells fight off bacteria and the red blood cells and platelets form scabs to seal wounds.


The Circulatory System maintains a stable body temperature. The blood vessels open when the body overheats or contracts flowing while someone is experiencing hypothermia.


Heart Attacks

Heart Attacks are caused by decreasing blood flow or oxygen supply increase. They can also be caused by blocked blood vessels. During the heart attack, a portion of your heart muscles die.

Heart Failure

This is when the heart is unable to pump blood everywhere. the lack of blood causes death. This condition can be caused by high blood pressure. What happens is the blood vessels contract, which delays blood flow. The heart has to work harder to pump the blood. If the heart works too hard it stops working.

Mitral Valve Prolapse

This is a very common disorder that seriously affects the heart's ability to pump through the body. The valve separating the atrium and the ventricle falls into the atrium where the ventricle closes. This can be heard with a stethoscope. The symptoms are chest pain, fatigue, & anxiety.

The Heart and Circulatory System - How They Work