H U M A N     B O D Y


Circulatory System

Heart Beating

Blood drop



The circulatory system is an organ system that distributes blood and lymph throughout the body.


Jobs of the circulatory system:

Passes nutrients (such as amino acids, electrolytes and lymph) , gases, hormones, blood cells, etc. to and from cells in the body to help fight diseases and help stabilize body temperature and pH to maintain homeostasis (the body's ability to physiologically regulate its inner environment).


Parts of the circulatory system:


The heart is an organ that pumps oxygenated blood to the body and deoxygenated blood to the lungs. In the human heart there is one atrium or auricle and one ventricle for each circulation, and with both a systemic and a pulmonary circulation there are four chambers in total: left atrium, left ventricle, right atrium and right ventricle. The right atrium is the upper chamber of the right side of the heart. The blood that is returned to the right atrium is deoxygenated (poor in oxygen) and passed into the right ventricle to be pumped through the pulmonary artery to the lungs for re-oxygenation and removal of carbon dioxide. The left atrium receives newly oxygenated blood from the lungs as well as the pulmonary vein which is passed into the strong left ventricle to be pumped through the aorta to the different organs of the body.

Blood Vessels:


These are large blood vessels that take oxygenated blood away from the heart to be distributed throughout the body. The aorta is the body's largest artery.


These blood vessels take deoxygenated blood from around the body back to the heart and lungs to be oxygenated.


These tiny blood vessels are where the exchange of oxygen and nutrients take place. The nutrients and oxygen are exchanged for wastes that are taken from the cells.


Blood is made up of red and white cells, plasma and platelets. Red blood cells carry nutrients and oxygen to the body's cells. Red blood cells are come from bone marrow. White blood cells help the body fight diseases and infections. The white cells are made in the bone marrow. Plasma is the watery part of the blood. Platelets are tiny cells that help clot the blood when a person gets a cut so they don't bleed to death.


Lymph is a fluid akin to blood plasma and contains white Blood cells. Lymph returns protein and excess interstitial fluid to the circulation. Lymph picks up bacteria and brings them to lymph nodes to be destroyed. Metastatic cancer cells can also be transported via lymph. Lymph also transports fats from the digestive system.


Heart Diagram


Heart Diagram


Heart Surface Anatomy


Heart Surface Anatomy


Arterial System


Arterial System

Close up of blood cells


Circulatory System Videos

Circulatory System Quiz



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