What Is the Human Heart?

The human heart is an organ that is the size of a human fist. It pumps blood throughout the human body. It is the primary organ of the human circulatory system. In men, the heart weighs between 280 and 340 grams, whereas, in women, it weighs between 230 and 280 grams. The human heart is located in the center of the chest—slightly to the left of the sternum (breastbone). It is located between the lungs. It is enclosed in a double-walled sac, which is called the pericardium. The pericardium protects the heart and anchors it within the chest. The fluid in the pericardium functions as a lubricant between the parietal pericardium (the outer layer) and the serous pericardium (the inner layer). During movements and contractions of the diaphragm and lungs, the fluid lubricates the heart.

Overview of the human heart
X-ray image of an overview of the human heart

Anatomy of the Human Heart

Dorsal view of the human heart
Schematic of dorsal view of the human heart

The human heart is made of four chambers: two upper chambers form the atria and two lower chambers form the ventricles. The “right heart” is composed of the right ventricle and right atrium. The “left heart” is composed of the left ventricle and left atrium. The septum, which is a wall of muscle, separates the two sides of the heart. The outer wall of the heart consists of three layers: The outermost layer (epicardium) forms the inner wall of the pericardium; the middle layer (myocardium) is composed of the muscle that contracts the heart; the inner layer (endocardium) lines the heart chambers. The atrioventricular valves, which consist of the tricuspid valve and the mitral valve, connect the heart’s upper and lower chambers.  The valves are anchored to the heart muscles by the heartstrings (chordae tendineae).

Ventral view of the human heart
Schematic of ventral view of the human heart

Function of the Human Heart

The human heart’s function is to maintain a constant blood flow throughout the body. This circulates nutrients among the cells and tissues and replenishes oxygen. The main functions of the heart are as follows:

  • The primary function of the human heart is to pump blood throughout the body.
  • The heart ensures that sufficient blood pressure is maintained in the body.
  • Blood from the heart delivers hormones, oxygen, glucose, and other components to various parts of the body.
  • There are two types of blood circulation in the human body: systemic circulation  and pulmonary circulation. 

In pulmonary circulation, a portion of blood circulation carries deoxygenated blood from the heart to the lungs and then brings oxygenated blood back to the heart. In the systemic circulation, another portion of blood circulation carries the oxygenated blood from the heart to all organs and tissues in the body, and the deoxygenated blood is carried back to the heart.

What Are the Medical Conditions of the Heart?

Some of the heart diseases are as follows:

  • Stable angina pectoris: It is a condition where the chest pain is caused because of insufficient blood supply to the heart, after strenuous physical activity. Narrowed coronary arteries are unable to supply the blood with sufficient oxygen to the heart during exertion. Upon rest, there is relief from these symptoms.
  • Coronary artery disease: It is a condition of narrowing of the coronary arteries that supply the blood to the heart. A heart attack occurs if there is complete blockage of the arteries from a sudden blood clot.
  • Myocardial infarction: It is a condition where some of the heart muscles die due to a lack of oxygen, when there is a sudden blockage of a coronary artery.
  • Unstable angina pectoris: It is an emergency condition that may precede a heart attack, cardiac arrest, or severe abnormal heart rhythm.
  • Arrhythmia (dysrhythmia): It is a condition of abnormal heart rhythm, which may affect the heart’s ability to pump blood effectively.
  • Congestive heart failure: It is a condition where the heart is unable to efficiently supply the blood to the body tissues. This term refers to the collection of fluid because of heart failure.
  • Myocarditis: It is a condition causing inflammation of the heart muscles.
  • Cardiomyopathy: It is heart disease that leads to abnormal enlargement, stiffness, and/or thickening of the heart. Consequently, the ability of the heart to supply the blood is weakened.
  • Pericardial effusion: It is a medical condition where fluid collects between the pericardium and the entire heart.
  • Pericarditis: It is the condition causing inflammation of the pericardium.
  • Heart valve diseases: There are diseases affecting the valves that direct blood flow to the heart.
  • Cardiac arrest: It is a condition where the heart function suddenly stops.

 Some Facts about the Human Heart

  • The human heart can beat 115,000 times a day.
  • The heart beating sound is caused when the valves open and close.
  • About 2,000 gallons of blood are pumped by the heart pumps per day.
  • If the blood vessel system were to be stretched, it has the capacity to extend over 60,000 miles.
  • We know that the human heart weighs less than a pound, but the heart is two ounces heavier in men than in women.
  • The heart beats slightly faster in women than in men.
  • As per the saying that laughter is good for the human heart, the heart indeed reduces stress and boosts the immune system.
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