The circulatory system is an organ system that
permits blood and lymph circulation to transport
nutrients (such as amino acids and
electrolytes), oxygen, carbon dioxide,
hormones, blood cells, etc. to and from cells in the
body to nourish it and help to fight diseases,
stabilize body tempreature and pH, and to
Blood is constantly circulating fluid providing the body with
nutrition , oxygen and waste removal. Blood is mostly liquid,
with numerous cells and proteins suspended in it, making blood
“thicker” than pure water. The average person has about 5 liters
(more than a gallon ) of blood.
The liquid called plasma makes up about half of the content of
blood. Plasma contains proteins that help blood to clot,
transport substances through the blood, and perform other
functions. Blood plasma also contains glucose and other
dissolved nutrients. About half of blood volume is composed of
Red blood cells, which carry oxygen to the tissues.
White blood cells, which fight infections.
Platelets , smaller cells that help blood to clot.
It takes 20 seconds for blood to circulate the entire
body , oxygenated blood leaves the aorta about one
mile an hour
The power output of heart ranges from 1-5 watts per
minute , which is equivalent to the usage of a 60 watt
bulb. It has been said that enough energy is produced
a day to drive a truck 20 miles.