The heart is a muscular organ present in all vertebrates that acts as a pump. The main function of the heart is to pump blood to all the parts of our body. The heart plays a very crucial role in our circulatory system. The Heart is present in center of the chest, protected by our ribcage.
The Heart is a Hollow muscular organ that has four chambers. To look at the structure of the heart, lets divide it into left and right side. The right side has the right atrium and the right ventricle. Similarly the
left side has the left atrium and the left ventricle. The upper chambers of the heart are called Auricles and the lower chambers are the ventricles
Blood flows in and out of the heart through structures called blood
vessels. The blood enters the right side of the heart through the superior and inferior vena cava, into the right atrium. The blood leaves the right side of the heart through the Pulmonary artery. Likewise, on the left side, blood enters the left atrium through the Pulmonary vein, and exits through the Aorta. The Aorta
is the largest of all the blood vessels in our body.
In a way, the Heart is a central HUB through which all blood passes.
This is the most important and interesting thing about the heart. The Heart muscle is called as the Myocardium. This special type of muscle present only in the heart. The myocardium is a sheath like muscle where each muscle fiber is linked with each other through intercalated disks. This specialized arrangement of cardiomyocytes makes it possible for conduction of electrical impulses. This makes the heart muscle a unique type of muscle in our body.
Lets look at the structure of the heart wall. The wall of the Heart is divided into 3 parts. The Pericardium, Myocardium and the endocardium.
Pericardium is the outer most layer of the heart wall. This layer is further divided into fibrous pericardium, parietal pericardium and the visceral pericardium. There is a gap present in-between the parietal and visceral pericardium that hosts the pericardial fluid. This cavity is called the pericardial cavity.
The middle layer of the heart is called the myocardium and the innermost layer of the heart is called the endocardium.
There are two specific sites in the heart the makes the heart work. One is located above the right atrium and the other is in-between the two ventricles and the auricles. These are called the Sino Atrial Node and the Atrio Ventricular node. The two nodes gives the heart the ability to pump blood constantly. They generate electrical impulses that make the blood flow both inside and outside the heart.
It starts with the SAN, the Sino Atrial Node produces electrical impulses that flows throughout the auricles causing them to contract and push the blood into the ventricles. When the impulses reach the AVN. The atrio ventricular node then distributes the impulses through out the ventricles. This makes them contract, and the blood from these ventricles exits through the