Human heart is one of the most important organs responsible for sustaining life. It is essentially a muscle, about the size of a clenched fist. The human heart functions throughout a person’s lifespan, pumping almost 200 million liters of blood. It roughly beats 2.5 billion times during a human lifespan, making it one of the most robust and hardest working muscles in the human body. The human heart is located between the lungs, behind, and slightly towards the left of the sternum. Two-thirds of the heart is situated on the left side of the chest, and the remaining part is balanced on the right side of the chest.
The Function of Human Heart
Human heart is a homologous organ, it functions no differently from any other vertebrates that possess a heart. Following are the main functions of the heart:
- Pumping blood throughout the body.
- Blood delivers oxygen, hormones, glucose, and other components to various parts of the body, including the human heart.
- It also ensures that adequate blood pressure is maintained in the body
External Structure of Heart
Pericardium: The pericardium is a fibre membrane found as an external covering around the heart. It protects the heart by producing a serous fluid, which serves to lubricate the heart and prevent friction between the surrounding organs. Apart from the lubrication, the pericardium also helps by holding the heart in its position and by maintaining a hollow space for the heart to expand itself when it is full. The pericardium has two exclusive layers—
- Visceral Layer: It directly covers the outside of the heart.
- Parietal Layer: It forms a sac around the outer region of the heart that contains the fluid in the pericardial cavity.
Structure of Heart Wall
The heart wall is made up of 3 layers, They are namely:
- Epicardium: It is the outermost layer of the heart. It is composed of a thin-layered membrane that serves to lubricate and protect the outer section.
- Myocardium: This is a layer of muscle tissue, and it constitutes the middle layer wall of the heart. It contributes to the thickness and responsible for the pumping action.
- Endocardium: It is the innermost layer that lines the inner heart chambers and covers the heart valves. Furthermore, it prevents the blood from sticking to the inner walls, thereby preventing potentially fatal blood clots.