THE HEARTKimberly Cai CN-3

Stephanie Syjueco CN-22

WHAT IS THE HEART?

The heart is the organ that supplies blood and oxygen to all parts of the body.

The heart is pear shaped and about the size of a fist.

The heart is an involuntary muscle, meaning that unlike the leg or arm muscles, the cardiac muscle is not under voluntary control.

WHERE IS THE HEART LOCATED?

The heart is located beneath the protective ribs on the left side.

It is located in the chest cavity

It is surrounded by a covering called the pericardium.

THE HEART

The heart is divided into four chambers, called the right and left atria and the right and left ventricles

DIFFERENT ANIMALS MAY HAVE DIFFERENT CHAMBERED HEARTS OR NONE AT ALL. FOLLOWING IS THE GENERAL ANATOMY OF THE HUMAN HEART.

PARTS OF THE HEART

MAIN FUNCTIONS OF THE HEART

The role of the heart is to pump oxygen-rich blood to every living cell in the body. In order to achieve its goal, it must continuously beat for a person’s entire lifespan. Because of its vital role, a non-beating heart always results in death

The heart beats almost like a clock, about 60 to 80 times per minute, CONTINUOUSLY, whether you are asleep or awake. The heartbeat is regulated by a small "battery" located in the right atrium called the SINUS NODE. Electric currents travel in the heart by means of minute fiber's in the wall of the heart, much like concealed wiring inside a room.

THE HEARTBEAT

The heartbeat is made up of systole and diastole, which are the two stages of a heartbeat.

SYSTOLE

Stage when the ventricles of heart are contracting resulting in blood being pumped out to the lungs and the rest of the body.

Thick, muscular walls of both ventricles contract.

Pressure rises in both ventricles, causing the bicuspid and tricuspid valves to close. Therefore, blood is forced up the aorta and the pulmonary artery.

The atria relax during this time. The left atrium receives blood from the pulmonary vein, and the right atrium from the vena cava.

DIASTOLE

Stage when the ventricles of the heart are relaxed and not contracting. During this stage, the atria are filled with blood and pump blood into the ventricles.

Thick, muscular walls of both ventricles relax. Pressure in both ventricles falls low enough

for bicuspid valves to open. The atria contract, and blood is forced into

the ventricles, expanding them. The blood pressure in the aorta is decreased,

therefore the semi-lunar valves close.

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