Heart

Your heart is a strong muscle.

It stays in your chest. It pumps blood to your whole body. This blood carries food and air to you.

It is about the size of your fist. Your heart has four small rooms inside. These rooms help the blood move in one way. Special doors called valves keep the blood from going back.

This keeps the blood flowing the right way. Your heart beats many times every minute.

Your heart is a strong, muscular organ.

It sits in the middle of your chest. It is about the size of a closed fist. The heart pumps blood through tubes called blood vessels. This set of steps is called the circulatory system.

The blood carries oxygen and nutrients to your body. It also carries waste away to your lungs.

The heart has four rooms, or chambers. There are two upper rooms called atria. There are two lower rooms called ventricles.

Special doors called valves sit between these rooms. They make sure blood flows in only one direction.

A tiny group of cells acts like a timer. This is the sinoatrial node. It makes an electric current. This current tells the heart to squeeze. When the heart squeezes, blood moves forward. The heart wall has three layers. The middle layer is called the myocardium. This is the thick muscle that does the pumping.

An adult heart beats about 72 times every minute while resting.

The heart is a muscular organ that keeps us alive.

It works by pumping blood through tubes called blood vessels. This whole setup is known as the circulatory system. The blood carries oxygen and nutrients to your body's tissues. It also picks up waste like carbon dioxide to take to the lungs.

In humans, the heart sits in the middle of the chest. This area is called the mediastinum. It is located between the lungs. An adult heart is about the size of a closed fist.

Inside, the heart is divided into four chambers. There are two upper chambers called atria. There are two lower chambers called ventricles.

The right atrium and right ventricle are called the right heart. The left atrium and left ventricle are the left heart.

Heart valves act like one-way doors. They prevent blood from flowing backward. The heart wall has three layers. These are the epicardium, the myocardium, and the endocardium.

A protective sac called the pericardium encloses the heart. It even holds a small amount of fluid.

The heart pumps using a special rhythm. A group of cells called the sinoatrial node acts as a pacemaker.

These cells create an electric current. This current makes the heart contract, or squeeze. The signal travels through the atrioventricular node. It then moves through the conduction system.

This electrical work makes the heart beat steadily. The left ventricle is much thicker than the right. This is because it needs more force to pump blood to the whole body.

Blood follows a very specific path through these chambers.

First, blood enters the right atrium from the body. It moves to the right ventricle and then to the lungs. In the lungs, the blood gets oxygen.

Then, oxygenated blood returns to the left atrium. It passes to the left ventricle and enters the aorta. From there, it travels to the rest of the body.

An adult heart beats about 72 times per minute while resting. This constant movement keeps everything flowing.

Sometimes, the heart can run into trouble.

In 2008, heart diseases were the most common cause of death globally. They accounted for 30% of all human deaths. Many of these cases come from coronary artery disease or stroke. Doctors who study the heart are called cardiologists.

They might use a stethoscope to listen to heart sounds. They can also use an ECG or an ultrasound called an echocardiogram.

Staying active and eating well can help keep the heart strong.

The heart is a muscular organ essential for sustaining life in humans and many animals.

It functions as a pump that drives blood through a network of blood vessels. Together, the heart and these vessels form the circulatory system. This system is vital because it delivers oxygen and nutrients to bodily tissues. Simultaneously, it collects metabolic waste products, such as carbon dioxide, to transport them to the lungs for removal.

In the human body, the heart is located within the mediastinum, which is the middle compartment of the chest. It sits between the lungs, though the left lung is actually smaller to accommodate the heart's position.

The organ is roughly cone-shaped, with a wide base at the top and a tapering bottom called the apex. An adult heart typically weighs between 250 and 350 grams. While often described as being the size of a closed fist, it may actually be slightly larger.

The entire organ is protected by a double-membraned sac known as the pericardium, which contains a small amount of fluid.

The heart is divided into four distinct chambers to manage blood flow. The two upper chambers are called the atria, which serve as receiving chambers. The two lower chambers are called the ventricles, which act as discharging chambers.

The right atrium and right ventricle are grouped together as the right heart. The left atrium and left ventricle are known as the left heart. Because the left ventricle must pump blood to the entire body, its muscular wall is much thicker than that of the right ventricle. The heart wall itself consists of three layers: the inner endocardium, the middle myocardium, and the outer epicardium.

To ensure blood moves in only one direction, the heart utilizes several specialized valves.

The atrioventricular valves sit between the atria and the ventricles. On the right side, the tricuspid valve has three cusps. On the left side, the mitral valve, or bicuspid valve, has two cusps. These valves are supported by papillary muscles and thin strands called chordae tendineae, which prevent the valves from being pushed backward during contraction.

Additionally, two semilunar valves exist at the exits of the ventricles. The pulmonary valve sits at the base of the pulmonary artery, and the aortic valve sits at the base of the aorta.

The movement of blood follows a precise, continuous sequence through these structures.

Deoxygenated blood enters the right atrium via the superior and inferior venae cavae. It then moves into the right ventricle, which pumps it through the pulmonary valve into the pulmonary circulation. In the lungs, the blood releases carbon dioxide and absorbs oxygen. This oxygenated blood returns to the left atrium through the pulmonary veins. It then passes into the left ventricle, which pumps it through the aortic valve into the aorta.

From the aorta, blood travels through arteries, arterioles, and capillaries to reach all body cells.

This entire process is driven by an internal electrical conduction system.

The rhythm begins with a group of specialized pacemaker cells in the sinoatrial node. These cells generate an electric current that triggers a contraction. This signal travels through the atrioventricular node and throughout the heart's conduction pathways.

This electrical activity causes the heart to beat at a regular rhythm. For a resting adult, this rate is typically close to 72 beats per minute.

Maintaining heart health is a major global medical priority. In 2008, cardiovascular diseases were the leading cause of death worldwide, accounting for 30% of all human deaths.

More than three-quarters of these deaths resulted from stroke or coronary artery disease. Common risk factors include smoking, high blood pressure, high cholesterol, and diabetes. Specialists called cardiologists study these conditions. They use tools like stethoscopes, ECGs, and echocardiograms, which utilize ultrasound, to diagnose and monitor heart health.