1. transport oxygen and carbon dioxide
2. distribute nutrients and transport of wastes
3. maintenance of body temperatures
4. circulation of hormones


Made up of three components:

1. A fluid in which materials are transported (blood)
2. vessels in which the fluid moves (blood vessels)
3. a pump (the heart)

Circulatory system is actually two systems:

Pulmonary circuit:

-the right side of the heart pumps blood to the lungs
– blood picks up oxygen and releases carbon dioxide
– blood returns to the heart, on the left side

Systemic circuit:

– the left side of the heart pumps blood to all parts of the body
– blood delivers oxygen and other nutrients
– blood returns to the heart, on the right side

The Heart

– two pumps, each pump is separated by the septum; a muscle wall
– the right pump, pumps to the pulmonary circuit
– the left pump, pumps to the systemic circuit
-each pump is made up of an atrium and a ventricle
atria receive blood from veins and pump into ventricles
ventricles receive blood from atria and pump blood into arteries
heart valves prevent blood from flowing backwards in the heart

Heart Rhythms, Sounds and Pressure

– the sinoatrial node sets the heart rhythm, about 72 beats per minute
– the lubb-dubb heart sounds are caused by the closing of the valves
diastole is when the heart is relaxed, fills up with blood (semilunar valves close)
systole is when atria push blood into the ventricles, then the ventricles push blood into the arteries (AV valves close)

Cite this article as: William Anderson (Schoolworkhelper Editorial Team), "The Human Circulatory System," in SchoolWorkHelper, 2019,

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