Normal Heart Anatomy

The main function of the heart is to deliver oxygen-rich blood to every cell in the body.

The arteries are the passageways through which the blood is delivered and the veins are the passageways through which the blood is collected and returned to the heart.

The adult heart weighs between 200 to 425 grams (7 to 15 ounces) and is about the size of your fist. Your heart is a muscle, which unlike other muscles of the body has to work around the clock to keep your blood circulating.

To understand the anatomy and function of the heart, we have divided the heart into two sections - Exterior and Interior

Exterior Anatomy

Vena Cava

The vena cava is a large vein that brings deoxygenated (impure) blood back to the heart and empties it in to the right atriuma.

Atria

There are two atria, the right atrium, and the left atrium, which are the two upper chambers of the four muscular chambers of the heart.

The right atrium collects the impure blood from the vena cava and delivers it to the right ventricle. This delivery is regulated by the tricuspid valve.

The left atrium collects the oxygenated blood from the lungs, via the pulmonary veins and delivers it to the left ventricle. This delivery is regulated by the mitral valve.

Ventricles

There are two ventricles, right and left, which are the two lower chambers of the four muscular chambers of the heart.

The right ventricle collects the impure blood from the right atrium and delivers it to the lungs for purification (oxygenation). This delivery is regulated by the pulmonary valve.

The left ventricle collects the pure blood from the left atrium and delivers it to the aorta (main artery) from where it is pumped to the rest of the body. This delivery is regulated by the aortic valve.

Pulmonary Artery

As part of the pulmonary circulation, the pulmonary artery carries the de-oxygenated blood from the right ventricle to the lungs for oxygenation.

Pulmonary Veins

Blood after oxygenation in the lungs, is brought back to the heart by pulmonary veins and delivered to left atrium.

Aorta

The Aorta the largest artery in the body, collects blood pumped from the left ventricle to branch and deliver the oxygen rich blood to various organs and tissues in the human body.

Pericardium

The pericardium is the fluid filled sac that surrounds the heart. The heart literally floats in this pericardial fluid.

The main function of the pericardium is to:

• Keep the heart within the chest cavity
• Act as a shock absorber preventing the heart from over expanding when blood volume increases

Coronary Circulation

The coronary circulation consists of the blood vessels that supply blood to, and remove blood from, the heart tissue. Coronary arteries supply oxygen rich blood to the heart and the coronary veins remove the deoxygenated blood from the heart.

Serious heart damage may occur when the coronary circulation is blocked.

Coronary Arteriesy

Blood is supplied to the heart by the coronary arteries. Two main coronary arteries branch off the aorta then branch into several smaller arteries that supply oxygen rich blood to the heart.

Coronary Veins

The deoxygenated blood from the heart muscle is collected by the coronary veins and drained into the right atrium.

Circulatory system

The heart acts a pump, delivering blood to the organs, tissues, and cells of your body through a complex network of arteries, arterioles, and capillaries. Blood is returned to your heart through venules (small veins) and veins.

Interior Anatomy

Heartbeat

The heart is a pump and each contraction of the heart represents one heartbeat.

Pulse or Heart Rate is the number of heartbeats per minute.

The heart rate is controlled by the brain and varies depending on, factors such as age, stress, exercise, surrounding temperature, and hormones.

The heartbeat is a two part pumping action- Systole (contraction) and Diastole (relaxation). Move your cursor over the labels to find out more.

Systole (Ventricular Contraction)

The series of activities in systole which happens at one particular moment are:

• The tricuspid and mitral valve shut to prevent backflow into the respective atria
• Blood from the right ventricle is pumped to the lungs through the pulmonary artery
• Blood from the left ventricle is pumped to the rest of the body through the aorta
• The Vvena cava empties the deoxygenated blood into the right atrium
• The pulmonary veins empty the oxygenated blood into the left atrium

In a normal resting adult, the heart beats about 72 times per minute (Pulse 72), which means all the above activities happen in less than one second.

Diastole (Ventricular rRelaxation)

The series of activities in diastole which happens at one particular moment are:

• The tricuspid and the mitral valve open
• Deoxygenated blood from the right atrium flows to the right ventricle
• Oxygen rich blood from the left atrium flows to the left ventricle

In a normal resting adult, the heart beats about 72 times per minute (Pulse 72), which means all the above activities happens in less than one second.

Heart Valves

The main function of the heart valves is to regulate and prevent the backflow of the blood.

There are four important valves in the heart.

Tricuspid Valve

The tricuspid valve regulates blood flow between the right atrium and the right ventricle.

It prevents the backflow of blood to the right atrium when the right ventricle pumps blood to the lungs.

Mitral Valve

The mitral valve regulates the blood flow between the left atrium and the left ventricle.

It prevents the backflow of blood to the left atrium when the left ventricle pumps blood through the aorta to the rest of the body.

Pulmonary Valve

The pulmonary valve regulates the de--oxygenated blood from the right ventricle to the lungs for purification.

Aortic Valve

The aortic valve regulates the oxygenated blood pumped from the left ventricle to the rest of the body.

Conduction System

The heart's pumping energy comes from a built-in electrical conduction system.

The sinoatrial node, SA node is called the heart's natural pacemaker that causes the atria to contract when the electrical impulse is released.

The signal is then passed on to the atrioventricular node, AV node, and then to the conduction pathways (bundle of His) to provide electrical stimulus to the ventricles.