Heart anatomy, physiology, functions- A complete Guide

Heart anatomy! The human heart is divided into four chambers, two on the left side and two on the right side. The upper two chambers are known as Atrium and the lower two chambers are known as Ventricles. Thus, the four chambers of the heart are left atrium, right atrium, left ventricle, and right ventricle. The direction of blood from the whole body is, to the right atrium which on contracts pour the blood into the right ventricle. The right ventricle sends this deoxygenated blood to the lungs which upon oxygenation sends this oxygen-containing blood to the left atrium and then left ventricle.

Your heart is located between the two lungs, behind the sternum and in the middle of the chest cavity. The heart is covered by a double layer membrane called pericardium which protects the heart from the external forces. Your heart weights between the 7 and 15 ounces and is larger than your hand fist. It is protected under the rib cage.

Right Side of Heart Anatomy

The right side of the heart received de-oxygenated blood from the body through the superior vena cava into the right atrium. The right atrium is shown on the left side of the picture. Blood from the right atrium is drained into the right ventricle to send it to the lung to be oxygenated. Blood flow from the right atrium to the right ventricle is controlled by the semilunar valves. These valves prevent the backflow of blood and have 3 cusps that open and closed according to the need of the heart.

Left Side Heart Anatomy

Same as the right side of the heart, the left side of the heart has left atrium and left ventricle. Oxygenated blood from the lungs is poured into the left atrium by pulmonary veins. Left atrium contracts and drain this oxygen-containing blood into the left ventricle by mitts valve. This valve has two cusps than the semilunar valve and prevents the backflow of blood. After the contraction of the left ventricle, blood is pumped to the whole body through the aorta.

Superior Vena Cava / Inferior Vena Cava

The deoxygenated blood from the whole body is poured into the right atrium by two large veins. Superior veins cava collect the blood from the arms, head, and neck, while inferior vena cava collects the blood from lower legs and abdomen.

Pulmonary Arteries & Pulmonary Veins

Pulmonary arteries carry the de-oxygenated blood from the right ventricle to the lungs to oxygenation. Pulmonary veins carry oxygenated blood from the lung to the left atrium upon oxygenation. The whole arterial system carries oxygenated blood and the whole venous system carries deoxygenated blood except pulmonary artery and pulmonary vein.


The largest artery which contains blood full of oxygen from the left ventricle and pumped it to the whole body by the large three main branches

  • Carotid branch

It supplies the blood to the head region.

  • Thoracic branch

It supplies blood to the truck and thoracic region.

  • Descending aorta

It supplies the abdominal region and lower limb.

Coronary Artery

The heart is a muscular beg which pumps the blood around its whole body. Like the other body muscles, it also needs oxygen to do the work. Therefore, this oxygen supply of the heart is maintained by the coronary arteries. This right and left coronary arteries are the main branch of the aorta which leaves the left ventricle with full oxygen-containing blood. Thus, pure rich oxygen is supplied to the heart.

If there is any lesion in the coronary arteries such as narrowing of the coronary artery, coronary thrombosis, fatty deposits around the coronary artery then oxygen supply and blood flow to the heart is compromised. Due to an improper oxygen supply, Ischemic Heart Diseases may occur due to loss of heart muscle functioning.

Heart Physiology

The heart anatomy is a vital organ of the body which pumps the blood and nourishing the whole cells of the body. The main functions of the heart are

  1. Oxygen-containing blood supplies to the whole cells of the body to keep them alive.
  2. Brain cells are kept alive by receiving the blood from the heart.
  3. Plasma volume and osmotic pressure are maintained.
  4. All the nutrients you are taking are delivered to the body by this pumping system.
  5. Waste products from the cells are removed by blood and oxygen is supplied to the cells by removing carbon dioxide.
  6. Inflammatory mediators, plasma proteins, hormones, etc are transferred from their site of production to the site of involvement through the blood system.

Heart Conduction System

Heart chambers are just a bag of muscles. Muscles are endocardium, myocardium, and pericardium. Heart contraction is actually a muscle contraction. How heart muscles contraction is regulated? Electrical impulses generate from the Sinoatrial SA node which is present at the top lateral side of the right atrium, is known as the Natural Pacemaker of heart.

These coming electrical impulses cause your heart muscle (the myocardium) to contract. These same electrical signals from SA nodes travel down through the Purkinje fibers or muscle fibers of the atria and ventricle to contract at the same time. This contraction of the heart muscles by electrical impulses is kept highly regulated, any abnormality in the pacemaker can cause irregular contraction of the heart such as arrhythmias.

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