Anatomy/Cardiovascular System

The cardiovascular system consists of the heart and the blood vessels. The heart is responsible for pumping the blood, the body's transport medium, around the body through the blood vessels.

The Heart
The adult heart is approximately the size of a fist and weighs between 250 and 350 grams.

It is located in the medial compartment of the mediastinum (see also thorax). The heart extends obliquely for 12 to 14 centimeters (5 inches), from the second rib to the fifth intercostal space. Approximately two-thirds of the mass of the heart lies to the left of the midsternal line (or midline). The heart is surrounded by the right and left lungs, which are themselves enveloped in their own pleural sacs.

Although rare, there is a medical condition known as dextrocardia in which the orientation of the heart is reversed.