Heart
In humans, the heart is a pulsating organ that pumps blood throughout the body. On average, the heart weighs about 10.5 ounces (300 grams). It is a four-chambered, cone-shaped organ about the size of a closed fist. It lies under the sternum (breastbone), nestled between the lungs. The heart is covered by a triple-layered, fibrous sac called the pericardium. This important organ is protected within a bony cage formed by the ribs, sternum, and spine.
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