Heart

The heart is a muscular organ that pumps blood throughout the body. It is located in the chest, slightly to the left of the midline. The heart is divided into four chambers: the left and right atria, and the left and right ventricles. The atria receive blood from the body and the lungs, while the ventricles pump blood out to the body and the lungs.

Structure of the Heart

The heart is made up of several layers, including the pericardium (a protective sac), the myocardium (muscle tissue), and the endocardium (inner lining). The heart also has four valves that ensure the blood flows in the correct direction: the tricuspid valve, the pulmonary valve, the mitral valve, and the aortic valve.

Function of the Heart

The main function of the heart is to pump blood throughout the body, delivering oxygen and nutrients to the cells and removing waste products. The heart achieves this through a rhythmic cycle of contraction (systole) and relaxation (diastole), which creates the pressure needed to propel the blood through the circulatory system.

Circulation

The heart is part of the circulatory system, which also includes blood vessels such as arteries, veins, and capillaries. Deoxygenated blood from the body enters the right atrium, is pumped to the lungs to pick up oxygen, and then returns to the left atrium. From there, the oxygenated blood is pumped out to the body through the left ventricle, supplying the cells with the oxygen and nutrients they need.

Study Guide

1. What are the four chambers of the heart?
2. Describe the structure of the heart.
3. Explain the function of the heart.
4. How does the circulation of blood occur in the heart?

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