Circulatory System

Circulatory system is the life support structure that delivers oxygen and nutrients to the cells of the different parts of the body and also transport waste away from the body.  It is composed of three major parts the heart, blood, and blood vessels.

The three major parts of the circulatory system and their functions:

Heart - pumps blood throughout the body.
Blood - carries oxygen, and nutrients to the different parts of the body.
Blood vessels - carries the blood throughout the body.  Blood vessels are classified as:

• Arteries -carry oxygenated blood away from the heart to the cells, tissues and organs of the body.
• Veins - carry deoxygenated blood back to the heart.
• Capillaries - are very tiny blood vessels that form a connection between arteries and veins.  This is where the exchange of gases occur.

Types of Circulation

1. Pulmonary circulation - is the movement of the blood from the heart to the lungs and back to the heart. 
2. Coronary circulation - is the movement of the blood through the tissues of the heart.
3. Systemic circulation - is the movement of the blood from the heart to the different parts of the body excluding the lungs.

The Human Heart

The heart is a muscle that is the same size of your fist.  It has four chambers, each chamber has corresponding function.  These are the right atrium, left atrium, right ventricle and left ventricle.

The right atrium receives the deoxygenated blood from the different parts of the body; the left atrium, receives the blood from the lungs; the right ventricle, pumps the blood to the lungs; the left ventricle, pumps the blood to the different parts of the body.  

There is a valve between atria and ventricles, to prevent the blood from flowing backwards.  The valves are like one-way doors that keep the blood from moving in one direction.  Valves control movement of blood into the heart chambers and out into aorta and pulmonary artery.

Valves of the Heart

• Tricuspid valve - is located between right atrium and right ventricle
• Pulmonary valve- is located between the right ventricle and pulmonary artery
• Mitral valve - is located between the left atrium and left ventricle
• Aortic valve is located between the left ventricle and the aorta

How the heart works

The right atrium receives the blood from the different parts of the body, and will pass to the right ventricle in which is the once responsible of pumping the blood to the lungs.  From the lungs the blood will again go back to the heart entering in the left atrium and to the left ventricle, and then it will be pump to the different parts of the body, and will then again go back to the heart for another cycle.