Lung

You have two lungs in your chest.

They sit on both sides of your heart. The right lung is bigger than the left.

Your lungs help you breathe. They take in the air you need. They also let out old air.

This helps your body stay healthy.

Air moves through many small paths. These paths look like tiny branches. The air reaches very small spots. These spots are like tiny bubbles.

Inside these bubbles, your body swaps air. It takes in the air you breathe. It sends it into your blood.

Your lungs also help you talk. Air moving through them makes sound.

Breathing keeps you going every day.

You have two lungs inside your chest.

They sit on either side of your heart. The right lung is bigger and heavier than the left. The left lung has a small space for your heart. Together, your lungs weigh about 1.3 kilograms.

Your lungs help you breathe through gas exchange. This is a way to swap air. Your lungs take oxygen from the air. Then, they move that oxygen into your blood. They also take carbon dioxide from your blood. Finally, they let that gas out when you breathe out.

Air travels through many tiny paths. It starts in the trachea, which is your windpipe. The air moves into tubes called bronchi. These tubes branch into even smaller parts called bronchioles. At the very end, the air reaches tiny bubbles called alveoli. There are 300 to 500 million of these bubbles!

Lungs also help you speak. The airflow through your lungs makes sound. A large muscle called the diaphragm helps you breathe. It moves to push air in and out.

Your lungs are the main organs of your respiratory system. They help you breathe by performing a task called gas exchange. This means they take oxygen from the air and move it into your blood. At the same time, they take carbon dioxide out of your blood and release it into the air.

Humans have two lungs inside the chest cavity. The right lung is bigger and heavier than the left lung. The left lung has a special notch called the cardiac notch to make room for your heart. Together, both lungs weigh about 1.3 kilograms.

Breathing works through a series of small steps. First, air enters through the trachea, or windpipe. The air then moves into tubes called bronchi, which branch into smaller bronchioles. These tubes divide again and again until the air reaches tiny bubbles called alveoli.

There are 300 to 500 million of these microscopic alveoli in your lungs. This is where the gas exchange actually happens. To help this process, a muscle called the diaphragm moves to drive the air in and out.

Lungs begin to form while a baby is still growing inside the womb. They start as an outpouching of the foregut, which is a tube that later becomes part of the digestive system.

When a fetus is growing, it stays in a fluid-filled sac. Because of this, the lungs do not breathe air yet. Instead, blood is diverted away from the lungs through a path called the ductus arteriosus. Once a baby is born, air begins to pass through the lungs. The diversionary path then closes so the lungs can start to work.

The lungs have a very complex and organized structure. Each lung is wrapped in a thin sac called a pleura. This sac has two layers that allow the lungs to slide without much friction.

The right lung is divided into three parts called lobes. The left lung only has two lobes. These lobes are further split into smaller sections called segments and lobules. The lungs also have a special blood supply. They receive deoxygenated blood to get oxygen, which is called pulmonary circulation. They also get a separate supply of oxygenated blood called bronchial circulation.

You can think of your lungs like a giant, branching tree. The trachea is like the thick trunk at the bottom. The bronchi and bronchioles are like the smaller branches spreading out. Finally, the alveoli are like the tiny leaves at the very ends of the branches.

Just as leaves help a tree interact with the air, your alveoli help you get the oxygen your body needs. Your lungs also provide the airflow needed for vocalization. This means the air moving through your system is what makes speech possible.

The lungs are the primary organs of the respiratory system in humans and many other animals. Their main role is to perform gas exchange. This process extracts oxygen from the atmosphere and transfers it into the bloodstream. Simultaneously, the lungs release carbon dioxide from the blood back into the atmosphere.

In mammals, the lungs are located near the backbone on either side of the heart. They are situated within the thoracic cavity of the chest. Besides breathing, the lungs provide the airflow necessary for vocalization, which makes speech possible.

Breathing is a mechanical process driven by muscular systems. In humans, the primary muscle responsible for driving this movement is the diaphragm. The lungs are part of the lower respiratory tract. This system begins at the trachea, which is the windpipe. The trachea branches into the bronchi, which then divide into smaller tubes called bronchioles.

These airways continue to divide until the air reaches microscopic sacs called alveoli. Together, the lungs contain approximately 2,400 kilometers of airways. Within these airways, there are between 300 and 500 million alveoli where gas exchange occurs.

The lungs have a highly organized anatomical structure. Each lung is enclosed within a pleural sac made of two membranes called pleurae. The outer parietal pleura lines the inner chest wall. The inner visceral pleura directly lines the surface of the lung. Between these layers is the pleural cavity, which contains a thin layer of lubricating pleural fluid. This allows the lung walls to slide against each other during breathing without much friction.

The visceral pleura also forms fissures that divide the lungs into sections called lobes. The right lung is larger and heavier, containing three lobes. The left lung is smaller and contains only two lobes. This difference exists because the left lung must accommodate the heart. The left lung even features a specific indentation called the cardiac notch to make room.

Within these lobes, the lungs are further subdivided into smaller units. The lobes are divided into bronchopulmonary segments. These segments are further divided into even smaller lobules. Each bronchopulmonary segment is a discrete unit with its own bronchus and arterial supply. This organization is clinically important because a segment can be surgically removed without affecting surrounding tissue.

The right lung has more lobes and segments than the left. The left lung has a projection called the lingula, which acts as an anatomical parallel to the right lung's middle lobe.

The lungs rely on a unique, dual blood supply to function. They receive deoxygenated blood from the heart through the pulmonary circulation. This blood enters the lungs specifically to pick up oxygen. At the same time, the lungs receive a separate supply of oxygenated blood through the bronchial circulation.

The tissue itself is supported by a complex extracellular matrix. This matrix contains elastic fibers made of the protein elastin. Elastin provides the lung compliance, or elasticity, needed for the lungs to stretch and recoil during the breathing cycle. Collagen fibers also intersperse between the capillaries and the alveolar walls to provide structure.

Lung development begins during the embryonic stage. The lungs start as an outpouching of the foregut, which is the tube that forms the upper digestive system.

While a fetus is in the amniotic sac, the lungs do not function to breathe air. During this time, blood is diverted away from the lungs through a structure called the ductus arteriosus. Once a baby is born and begins to breathe air, this diversionary duct closes. This allows the lungs to begin the process of respiration.

Various conditions can affect the health of the respiratory tract and lung tissue. Diseases such as pneumonia and lung cancer can impact the lungs. Chronic obstructive pulmonary disease (COPD) and emphysema are other serious conditions. These chronic diseases can be related to smoking or exposure to harmful substances.

Additionally, bronchitis can affect the airways of the respiratory tract. Medical terminology for these subjects often uses specific roots. Terms related to the lungs frequently begin with "pulmo-", from the Latin *pulmonarius*, or "pneumo-", from the Greek word for lung.