The heart is a hollow, muscular organ approximately the size of a fist, consisting of four chambers. It is enclosed in the pericardium, a fibrous sac with two layers: the visceral and parietal pericardium, separated by a fluid-filled space containing serous fluid to reduce friction.

The heart has three layers: the innermost endocardium, the muscular myocardium, and the outer epicardium, all working together for optimal cardiac function.

Chambers of the Heart

The heart is made up of four chambers, comprising two atria and two ventricles.

The atria receive blood while the ventricles pump it out.

The venae cavae include the superior vena cava (SVC) and inferior vena cava (IVC)

with coronary sinus, which carries deoxygenated blood to the right atrium and pumps it to the right ventricle.

The right ventricle transfers blood to the lungs via the pulmonary artery for oxygenation.

The left atrium receives oxygenated blood via the pulmonary veins and transports it to the left ventricle, which pumps it into systemic circulation through the aorta.

Valves of the Heart

Heart valves play a vital role in maintaining unidirectional blood flow.

The atrioventricular (AV) valves, consisting of the tricuspid and mitral valves, divide the atria from the ventricles. The tricuspid valve positions between the right atrium and the right ventricle, whereas the mitral valve is between the left atrium and the left ventricle.

The semilunar valves, including the pulmonic and aortic valves, are found between the ventricles and the major arteries. The pulmonic valve regulates blood flow from the right ventricle to the pulmonary artery. In contrast, the aortic valve manages blood flow from the left ventricle to the aorta.

Myocardium

The heart's myocardium, a thick muscular layer, comprises myocytes arranged in a spiral pattern. This unique arrangement allows for efficient blood ejection through coordinated twisting and compression.