Human Heart


Image Caption : Heart within Chest : The heart is located slightly to the left of the center of the chest, between the two lungs. This image shows the location of the heart within a person's ribcage and the network of arteries nearby in the thorax and neck. The subclavian arteries can be seen bringing blood from the heart to the arms. The common carotid arteries run from the heart up into the neck where they will branch to supply the head and neck with blood.

What Is the Heart?

Your heart is a muscular organ that pumps blood to your body. Your heart is at the center of your circulatory system. This system consists of a network of blood vessels, such as arteries, veins, and capillaries. These blood vessels carry blood to and from all areas of your body.

An electrical system controls your heart and uses electrical signals to contract the heart's walls. When the walls contract, blood is pumped into your circulatory system. Inlet and outlet valves in your heart chambers ensure that blood flows in the right direction.

Your heart is vital to your health and nearly everything that goes on in your body. Without the heart's pumping action, blood can't move throughout your body.

Your blood carries the oxygen and nutrients that your organs need to work well. Blood also carries carbon dioxide (a waste product) to your lungs so you can breathe it out.

A healthy heart supplies your body with the right amount of blood at the rate needed to work well. If disease or injury weakens your heart, your body's organs won't receive enough blood to work normally.

National Heart Lung and Blood Institute / NIH

The heart is a muscular organ in humans and other animals, which pumps blood through the blood vessels of the circulatory system. Blood provides the body with oxygen and nutrients, and also assists in the removal of metabolic wastes. The heart is located in the middle compartment of the mediastinum in the chest.

In humans, other mammals and birds the heart is divided into four chambers: upper left and right atria; and lower left and right ventricles. Commonly the right atrium and ventricle are referred together as the right heart and their left counterparts as the left heart. Fish in contrast have two chambers, an atrium and a ventricle, while reptiles have three chambers. In a healthy heart blood flows one way through the heart due to heart valves, which prevent backflow. The heart is enclosed in a protective sac, the pericardium, which also contains a small amount of fluid. The wall of the heart is made up of three layers: epicardium, myocardium, and endocardium.

The heart pumps blood through both circulatory systems. Blood low in oxygen from the systemic circulation enters the right atrium from the superior and inferior vena cavae and passes to the right ventricle. From here it is pumped into the pulmonary circulation, through the lungs where it receives oxygen and gives off carbon dioxide. Oxygenated blood then returns to the left atrium, passes through the left ventricle and is pumped out through the aorta to the systemic circulation−where the oxygen is used and metabolized to carbon dioxide. In addition the blood carries nutrients from the liver and gastrointestinal tract to various organs of the body, while transporting waste to the liver and kidneys. In the healthy organism each heartbeat causes the right ventricle to pump the same amount of blood into the respiratory organ as the left ventricle pumps to the body. Veins transport blood to the heart and carry deoxygenated blood - except for the pulmonary and portal veins. Arteries transport blood away from the heart, and apart from the pulmonary artery hold oxygenated blood. Their increased distance from the heart cause veins to have lower pressures than arteries. The heart contracts at a resting rate close to 72 beats per minute. Exercise temporarily increases the rate, but lowers resting heart rate in the long term, and is good for heart health.

Cardiovascular diseases (CVD) are the most common cause of death globally as of 2008, accounting for 30% of deaths. Of these more than three quarters follow coronary artery disease and stroke. Risk factors include: smoking, being overweight, little exercise, high cholesterol, high blood pressure, and poorly controlled diabetes, among others. Diagnosis of CVD is often done by listening to the heart-sounds with a stethoscope, ECG or by ultrasound. Specialists who focus on diseases of the heart are called cardiologists, although many specialties of medicine may be involved in treatment.



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