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- In humans and other mammals and in birds, the heart is a four-chambered double pump that is the centre of the circulatory system. In humans it is situated between the two lungs and slightly to the left of centre, behind the breastbone; it rests on the diaphragm, the muscular partition between the chest and the abdominal cavity.
Nov 10, 2024 · The heart is a muscular organ that pumps blood throughout the body via the circulatory system. It is approximately the size of a fist and consists of four chambers: two atria and two ventricles. The heart is composed of specialized muscle tissue, known as myocardium , and is encased within a double-layered protective sac called the pericardium .
Oct 31, 2024 · In humans and other mammals and in birds, the heart is a four-chambered double pump that is the centre of the circulatory system. In humans it is situated between the two lungs and slightly to the left of centre, behind the breastbone; it rests on the diaphragm, the muscular partition between the chest and the abdominal cavity.
- The Editors of Encyclopaedia Britannica
- In humans, the heart is situated between the two lungs and slightly to the left of center, behind the breastbone. It rests on the diaphragm, the mu...
- The heart consists of several layers of a tough muscular wall, the myocardium. A thin layer of tissue, the pericardium, covers the outside, and ano...
- The pumping of the heart, or the heartbeat, is caused by alternating contractions and relaxations of the myocardium. These contractions are stimula...
- The rhythmic noises accompanying the heartbeat are called heart sounds. The two distinct sounds are heard, a low, slightly prolonged “lub” (first s...
Mar 10, 2015 · Heart. The heart is a mostly hollow, muscular organ composed of cardiac muscles and connective tissue that acts as a pump to distribute blood throughout the body’s tissues. The heart is the...
Jun 11, 2024 · The heart is the pump that moves blood around your body. It has four main parts: two upper chambers called atria and two lower chambers called ventricles. These parts work together to get oxygen-rich blood to your body and oxygen-poor blood back to your heart.
- The Heart Wall Is Composed of Three Layers. The muscular wall of the heart has three layers. The outermost layer is the epicardium (or visceral pericardium).
- The Atria Are the Heart’s Entryways for Blood. The left atrium and right atrium are the two upper chambers of the heart. The left atrium receives oxygenated blood from the lungs.
- Each Heart Beat Is a Squeeze of Two Chambers Called Ventricles. The ventricles are the two lower chambers of the heart. Blood empties into each ventricle from the atrium above, and then shoots out to where it needs to go.
- The Valves Are Like Doors to the Chambers of the Heart. Four valves regulate and support the flow of blood through and out of the heart. The blood can only flow one way—like a car that must always be kept in drive.
Location and size of the heart. The heart is located under the rib cage -- 2/3 of it is to the left of your breastbone (sternum) -- and between your lungs and above the diaphragm. The heart is about the size of a closed fist, weighs about 10.5 ounces, and is somewhat cone-shaped.
The heart is located in the front of the chest, just behind and slightly left of the breastbone, and between the left and right lungs. Because the heart sits more in the left side of the chest, the left lung is slightly smaller to make room. The ribcage protects the heart. Heart anatomy.
