The heart is an organ which beats continuously to act as a pump for the transport of blood.
The heart is located in the chest cavity with its lower tip slightly tilted towards the left . Heart like fist. Your heart is roughly the size of your fist. the heart has four chambers. The two upper chambers are called the atria (singular: atrium) and
the two lower chambers are called the ventricles. The partition between the chambers helps to avoid mixing up of blood rich in oxygen with the blood rich in carbon dioxide.
To understand the functioning of the circulatory system, start from the right side of the heart . the blood flow from the heart to the lungs and back to the heart from where it is pumped to the rest of the body.