- Myocardium: The thick middle muscular layer that contracts to pump blood. It consists of cardiac muscle fibers, known as cardiomyocytes, which are arranged in a spiral pattern.
- Endocardium: The thin inner lining of the heart that covers the chambers and valves. It is composed of a layer of endothelial cells supported by connective tissue.
- Pericardium: The tough outer sac that encloses the heart, providing protection and support. It consists of three layers: the outer fibrous pericardium, the middle serous pericardium, and the inner visceral pericardium.
- Valves: Four valves regulate blood flow within the heart, preventing backward flow. These valves include the mitral (bicuspid) valve between the left atrium and ventricle, the aortic valve between the left ventricle and aorta, the tricuspid valve between the right atrium and ventricle, and the pulmonic valve between the right ventricle and pulmonary artery.
- Chambers: The heart consists of four chambers, two upper atria, and two lower ventricles. The left side of the heart receives and pumps oxygenated blood to the body, while the right side receives and pumps deoxygenated blood to the lungs for oxygenation.
- Blood vessels: The heart is supplied with blood by the coronary arteries, which branch off from the aorta. These arteries provide oxygen and nutrients to the heart muscle. Deoxygenated blood from the heart is collected by the coronary sinus and drained into the right atrium.
- Electrical conduction system: The heart's rhythmic contractions are coordinated by the electrical conduction system. This system includes the sinoatrial (SA) node, located in the right atrium, which generates the electrical impulses that initiate each heartbeat. The impulses then travel through the atrioventricular (AV) node, located between the atria and ventricles, before spreading through specialized pathways called the bundle of His and Purkinje fibers to cause the ventricles to contract.
Overall, the human heart is a marvel of biological engineering that relies on the intricate interplay of these different components to function efficiently and maintain circulation throughout the body.
