INTRODUCTION TO ANATOMY AND PHYSIOLOGY

The Heart

The function of the Heart is to pump blood around the body in its entirety!  

It is positioned in the Mediastinum (this is the partition located between the lungs and thoracic cavity). About two-thirds of the heart lies to the left of the median line. Its pointed apex rests on the diaphragm at the level of the fifth intercostal space and points towards the left hip. Its broader, superior aspect is called the base and it lies beneath the second rib and points towards the right shoulder.

The heart is divided into 2 halves – each of these has a specific function. (The heart itself is a muscle and is hollow)

  • Right Side – this receives deoxygenated blood from the body, and this is then pumped to the lungs for oxygenating.
  • Left Side – this receives the oxygenated blood from the lungs which is then pumped to the rest of the body.

These halves have the same function in that they both receive and deliver blood so both possess an

  • Atrium – receiving chamber.
  • Ventricle – delivery chamber.

Valves separate the chambers to prevent the blood flowing backwards.

Superior left and right atria:

The atria are the receiving chambers, and they receive blood from the veins. The atria are separated by the interatrial septum. The walls of both these chambers are thin because they only need to deliver blood into the ventricles beneath them.

Inferior left and right ventricles:

The ventricles are the delivery chambers, and they pump blood into the arteries. The ventricles are separated by the interventricular septum. The walls of both these chambers are thick because they need to pump blood out of the heart. The walls of the left ventricle are two to four times thicker than those on the right because the ventricle pumps blood throughout the entire body while the right only pump it to the lungs.

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