Heart
Human Anatomy · Physiology · Medicine
Say it: HART
The heart is the hollow, muscular organ in the chest whose four chambers pump blood through the lungs and then around the rest of the body.
Definition
What is the heart?
The heart is a fist-sized muscular pump in the middle of the chest, between the lungs and tilted to the left, held in a protective sac called the pericardium. Its wall has three layers: a thin outer epicardium, a thick middle myocardium made of cardiac muscle, and a smooth inner lining, the endocardium.
Inside are four chambers. The two upper atria receive blood and the two lower ventricles pump it out. The right side sends oxygen-poor blood to the lungs, the pulmonary circuit, while the left side, with a much thicker ventricle wall, drives oxygen-rich blood through the aorta to the body, the systemic circuit. Four valves, the tricuspid, pulmonary, mitral and aortic, keep blood flowing one way. Each beat starts in the sinoatrial node, a natural pacemaker in the right atrium, and spreads through a conduction system that makes the chambers contract in order.
The heart muscle has its own blood supply, the coronary arteries. When fatty plaque narrows them, the result is coronary artery disease, and a sudden blockage can kill part of the muscle in a heart attack.
Word parts
Where does the word “heart” come from?
- cardi-
- heart; used in words such as cardiac and cardiologyGreek kardia
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Terms that go with it
- Cardiac outputCardiac output is the volume of blood each ventricle of the heart pumps in one minute, equal to heart rate multiplied by stroke volume.
- Blood pressureBlood pressure is the force that circulating blood exerts on the walls of the arteries, recorded as systolic over diastolic pressure in mm Hg.
- AtherosclerosisAtherosclerosis is a disease in which fatty plaque builds up inside artery walls, stiffening and narrowing the arteries and reducing blood flow.
- InfarctionInfarction is the death of an area of tissue, called an infarct, caused by a sudden loss of its blood supply, as in a heart attack or a stroke.
- HypertensionHypertension is a long-term condition in which the pressure of blood against artery walls stays higher than normal, straining the heart and vessels.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
- OpenStax Anatomy and Physiology 2e, 19.1 Heart Anatomy
- OpenStax Anatomy and Physiology 2e, 19.2 Cardiac Muscle and Electrical Activity
- NHLBI: How the Heart Works
- NCBI MeSH: Heart
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