The Structure and Function of the Circulatory System 
Teacher E

The human circulatory system is a transportation system
Nutrients and oxygen are carried to living tissue within the body by approximately 9 pints of blood through 100,000 miles of vessels
The primary parts of the system are the heart, blood cells, and vessels
The human heart, a pump, is made of cardiac muscle
Cardiac muscles have a unique feature of forming connections between two adjacent cardiac cells
This allows the muscle cells to contract powerfully and quickly involuntarily
The brain is unable to increase or decrease the heart's beating
The heart is comprised of four chambers; two upper chambers called atriums, and two lower chambers called ventricles
The blood flows through the right side to the lungs where it picks up oxygen
The blood then returns to the right
Next, it flows into the left where it is pushed with tremendous force to all body parts
The heart is equipped with valves to prevent blood from flowing backward
The opening and closing of the valves cause the lub-dub sound associated with the heart
A swishing sound indicates a back flow of blood into the heart caused by a faulty valve
Arteries carry oxygen rich blood away from the heart
The veins, a blue color, carry blood toward the heart
Veins carry blood with carbon dioxide to be cleansed by the lungs
Problems can occur
Fat deposits can restrict the blood flow causing a heart attack
Weak vessels can balloon causing aneurysms
Many suffer from clots and varicose veins