Heart and it's function

 In most animals, the heart is a muscular organ. This organ circulates blood via the circulatory system's blood arteries. [1] Pumped blood transports oxygen and nutrients to the body while transporting metabolic waste like carbon dioxide to the lungs. [2] In humans, the heart is about the size of a closed fist and is placed in the middle compartment of the chest, between the lungs.
The heart is split into four chambers in humans other animals and birds: upper left and right atria and bottom left and right ventricles. [4] The right atrium and ventricle are commonly referred to as the right heart, whereas their left counterparts are referred to as the left heart. [6] In contrast, fish have two chambers, an atrium and a ventricle, whereas most reptiles have three. [5] Blood goes one way through in the healthy heart thanks to heart valves that prevent backflow. [3] The heart is surrounded by a protective sac called the pericardium, which also contains some fluid. The heart's wall is composed of three layers: epicardium, myocardium, and endocardium. [7]
The rhythm of the heart is governed by a set of pacemaker cells in the sinoatrial node. These create a current that causes the heart to contract by passing through the atrioventricular node and the heart's conduction system. Deoxygenated blood enters the heart via the right atrium from the superior and inferior venae cavae and travels to the right ventricle in humans. It is then pushed into the pulmonary circulation and delivered to the lungs, where it takes oxygen and emits carbon dioxide. The oxygenated blood then returns to the left atrium, travels through the left ventricle, and is pushed out into systemic circulation through the aorta, passing through arteries, arterioles, and capillaries.
where nutrients and other substances are transferred between blood arteries and cells, losing oxygen and obtaining carbon dioxide before returning to the heart via venules and veins. [8] The heart beats at a pace similar to 72 beats per minute during rest. [9] Exercise temporarily raises the heart rate, but reduces it in the long run and is beneficial to heart health. [10]

Position and shape 

The human heart is located in the center of the thorax, with the apex pointing to the left.

[14] The human heart is located in the mediastinum, between T5 and T8 thoracic vertebrae. 

The pericardium is a double-membraned sac that surrounds and attaches to the heart. 

[15] 

The back surface of the heart is near the vertebral column, and the front surface is behind the sternum and rib cartilages. 

[7] 

The venae cavae, aorta, and pulmonary trunk all attach to the upper part of the heart. 

The upper portion of the heart is located at the third costal cartilage level.

The heart is made up of four chambers: two higher atria, which serve as receiving chambers, and two lower ventricles, which serve as discharging chambers. 

The atria connect to the ventricles through the atrioventricular septum's atrioventricular valves. 

This divide is also apparent on the heart's surface as the coronary sulcus. 

[18] The right atrial appendage, or auricle, is an earshaped structure in the upper right atrium, whereas the left atrial appendage is in the upper left atrium. 

[19] 

The right atrium and the right ventricle together are sometimes referred to as the right heart. 

Similarly, the left atrium and the left ventricle together are sometimes referred to as the left heart.

The heart is made up of four chambers: two higher atria, which serve as receiving chambers, and two lower ventricles, which serve as discharging chambers. 

The atria connect to the ventricles through the atrioventricular septum's atrioventricular valves. 

This divide is also apparent on the heart's surface as the coronary sulcus. 

[18] The right atrial appendage, or auricle, is an earshaped structure in the upper right atrium, whereas the left atrial appendage is in the upper left atrium. 

[19] 

The right atrium and the right ventricle together are sometimes referred to as the right heart. 

Similarly, the left atrium and the left ventricle together are sometimes referred to as the left heart.

The  heart's chambers are separated by four valves.

One valve is located between each atrium and ventricle, while one valve is located at the  ventricle's outlet.

The atrioventricular valves are the valves that connect the atria and ventricles.

The tricuspid valve is located between the right atrium and the right ventricle.

The tricuspid valve has three cusps that connect to chordae tendineae and three papillary muscles known as the anterior, posterior, and septal muscles depending on their positions.