The Heart

 

 

Structure

 

In humans, the heart is roughly the size of a large fist and weighs between about 10 to 12 ounces (280 to 340 grams) in men and 8 to 10 ounces (230 to 280 grams) in women. 

 

The heart is found between the lungs in the mediastinum (the central part of the thoracic cavity.) 

 

The human heart has four chambers: two upper chambers (the atria) and two lower ones (the ventricles). The right atrium and right ventricle together make up the right side of the heart, and the left atrium and left ventricle make up the left side of the heart.

 

The left ventricle has a thicker muscular wall compared to the right because it has to pump blood through the larger systemic circuit. 

 

There are four valves in the heart that function to keep the blood flowing in the right direction. These are:

 

• The tricuspid valve: Found between the right atrium and right ventricle

• The bicuspid valve (mitral valve): Found between the left atrium and left ventricle

• The pulmonary valve: Found between the right ventricle and pulmonary artery

• The aortic valve: Found between the left ventricle and aorta

 

A wall of muscle called the septum separates the two sides of the heart. The sinoatrial node produces the electrical pulses that drive heart contractions.

 

 

Function

The main function of the heart is to pump blood around the pulmonary circuit to collect oxygen from the lungs, and the systemic circuit delivering oxygen to all of the bodies cells and removing carbon dioxide.

 

Images courtesy of dream designs & Meawpong3405 at FreeDigitalPhotos.net