How the lungs work
- Article
- 2021-02-27
Your lungs are a pair of organs in your chest. They have a spongy texture and are pinkish-gray in color.
When you inhale (inhale), air enters your lungs and oxygen from the air moves from your lungs to your blood. At the same time, carbon dioxide, a waste gas, moves from your blood to the lungs and is exhaled (exhaled). This process is called gas exchange and is essential to life.
In addition to the lungs, your respiratory system includes the trachea (windpipe), muscles of the chest wall and diaphragm, blood vessels and tissues that allow breathing and gas exchange. Your brain controls your breathing rate (how fast or slow you breathe) by sensing that your body needs oxygen and the need to get rid of carbon dioxide.
Healthy lifestyle habits, such as exercise and no smoking, can help prevent lung injury and disease.
The respiratory system
Your lungs lie in your chest cavity on each side of your heart. The right lung is divided into three lobes (sections) and the left lung is divided into two lobes. Your left lung is slightly smaller than your right lung, because your heart takes up some space on the left. When you breathe in, air enters your airways and travels to the alveoli (air sacs) in your lungs. Gas exchange takes place here.
The circulatory system, which consists of the heart and blood vessels, supports the respiratory system by bringing blood to and from the lungs. The circulatory system helps to deliver nutrients and oxygen from the lungs to tissues and organs throughout the body and to remove carbon dioxide and waste products. Other body systems that work with the respiratory system include the nervous system, the lymphatic system, and the immune system.
Respiratory tract
The airways are ducts that carry oxygen-rich air to the alveoli in your lungs. They also carry the waste gas carbon dioxide from your lungs. The airways include these parts of your body:
- Mouth
- Nose and coupled air passages called the nasal cavity and sinuses
- Larynx (larynx)
- Trachea (windpipe)
- Tubes, bronchi, or bronchi, and reeds
- Small tubes called bronchioles that branch off from the bronchi
Air enters your body
Air first enters your body through your nose or mouth, which moisturizes and warms the air, as cold, dry air can irritate your lungs. The air then travels down your larynx and down your windpipe. Rings of tough tissue called cartilage act as a support to keep the bronchi open.
In your lungs, the bronchi branch into thousands of thinner tubes called bronchioles. The bronchioles end in clusters of tiny air sacs called alveoli.
Air fills the air sacs of your lungs
Your lungs have about 150 million alveoli. Normally, your alveoli are elastic, which means that their size and shape can easily change. Alveoli can expand and contract easily because their insides are covered with a substance called surfactant. Surfactant reduces the work required to breathe by helping the lungs to inflate more easily when you inhale and by preventing the lungs from collapsing when you exhale.
Each of these alveoli is made up of a network of small blood vessels called capillaries. The capillaries are connected to a network of arteries and veins that move blood around your body.
Oxygen-deficient blood flows through the lungs
The pulmonary artery and its branches supply blood to the capillaries that surround the alveoli. This blood is rich in carbon dioxide and low in oxygen.
Oxygen flows in your blood
Carbon dioxide moves from the blood to the air in the alveoli. At the same time, oxygen moves from the air to the blood in the capillaries.
How does my body protect the airways from food or bacteria?
How your body regulates breathing
The body's muscles and nervous system help control your breathing.
The muscles used for breathing
The lungs are like sponges; they cannot expand (grow) on their own. Muscles in your chest and abdomen contract (contract) to create a slight vacuum around your lungs. This causes air to flow in. When you exhale, the muscles relax and the lungs deflate on their own, much like an elastic balloon deflates when it doesis left in the air.
The respiratory muscles include the:
- Diaphragm, a dome-shaped muscle under your lungs. It separates the chest cavity from the abdominal cavity. The diaphragm is the main muscle used for breathing.
- The muscles between your ribs, called intercostal muscles, play a role in breathing during physical activity.
- Abdominal muscles help you exhale when you breathe quickly, such as during physical activity.
- Muscles of the face, mouth and pharynx. The pharynx is the part of the throat immediately behind the mouth. These muscles control the lips, tongue, soft palate, and other structures to aid in breathing. Problems with these muscles can narrow the airway, make breathing difficult, and contribute to sleep apnea.
- Muscles in the neck and collarbone area help you inhale.
Damage to the nerves in the upper spinal cord can interfere with movement of your diaphragm and other muscles in your chest, neck, and abdomen. This can happen as a result of a spinal cord injury, a stroke or a degenerative disease such as muscular dystrophy. The damage can cause respiratory failure. Ventilator support or oxygen therapy may be required to maintain oxygen levels in the body and protect organs from damage.
The nervous system
Your breathing usually does not require any attention because it is controlled by the autonomic nervous system, also called the involuntary nervous system.
- The parasympathetic system slows down your breathing rate. It causes your bronchi to narrow and dilate the lung blood vessels.
- The sympathetic system increases your breathing rate. It makes your bronchi dilate and constrict lung blood vessels.
Your breathing changes depending on how active you are and the state of the air around you. For example, you need to breathe more often when you exercise. Sometimes you can control your breathing pattern, such as when holding your breath or singing.
To adjust your breathing to changing needs, your body has sensors that send signals to the respiratory centers in the brain.
- Sensors in the airways detect irritants in the lungs. The sensors can cause sneezing or coughing. In people with asthma, the sensors can cause the muscles around the airways in the lungs to contract. This makes the airways smaller.
- Sensors in the brain and near blood vessels detect carbon dioxide and oxygen levels in your blood.
- Sensors in your joints and muscles detect the movement of your arms or legs. These sensors can play a role in increasing your breathing rate when you are physically active.
What breathing does for the body
Breathing involves two phases: inhale and exhale. If you have breathing problems, gas exchange may be disrupted, which could be a serious health problem.
Breathe in
When you inhale or inhale, your diaphragm contracts and moves downward. This expands the space in your chest cavity and your lungs expand in it. The muscles between your ribs also help enlarge the chest cavity. They contract to pull your rib cage upward and outward as you inhale.
As your lungs expand, air is drawn in through your nose or mouth. The air flows through your windpipe and into your lungs. After you pass through your bronchi, the air travels to the alveoli or air sacs.
Gas exchange
Through the thin walls of the alveoli, oxygen from the air enters your blood into the surrounding capillaries. At the same time, carbon dioxide moves from your blood to the air sacs. The oxygen in your blood is carried in your red blood cells by a protein called hemoglobin.
The oxygenated blood from your lungs is carried through the pulmonary veins to the left side of the heart. The heart pumps blood to the rest of the body, where oxygen in the red blood cells travels from the blood vessels to your cells.
Your cells use oxygen to make energy so that your body can function. During this process, your cells also produce a waste gas called carbon dioxide. Carbon dioxide must be exhaled or else it can damage your cells.
Carbon dioxide travels from the cells to the
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