It's here where fresh oxygen from the air is exchanged for carbon dioxide in the blood. You have two lungs, the left lung and the right lung. The left lung is slightly smaller and has a notch to give room for the heart.
Each lung is divided into lobes—the left lung has two and the right lung has three—which are similar to balloons filled with sponge-like tissue. Each lobe receives air from its own branch of the bronchial tree, but they all have the same function: bringing oxygen into the bloodstream and removing carbon dioxide.
That's why it's possible but by no means ideal to live with just one lung. When you inhale, your lungs expand to hold the incoming air. How much air they hold is called lung capacity and varies with a person's size, age, gender and respiratory health.
The maximum amount of air an average adult male's lungs can hold is about six liters that's the same as about three large soda bottles. There's some math involved to get to that number, but basically, it's adding up air from a normal breath, extra air you can force in, additional air you can force out after regular exhaling and the air that's left in the lungs after all that. Every day, you breathe in just over 2, gallons of air—enough to almost fill up a normal-sized swimming pool.
That's a lot of air. It's the amount needed to oxygenate approximately 2, gallons of blood pumped through your heart daily. Because lungs are constantly exposed to the external environment, they need some protection from dust, germs and other unwanted matter. That's where mucus comes in. Your bronchial tubes are lined with cilia they're like thin little hairs that carry mucus up into your throat to trap those yucky intruders until you cough, sneeze , clear your throat or swallow to get rid of them.
The thoracic cavity, or chest cavity, always has a slight, negative pressure which aids in keeping the airways of the lungs open. During the process of inhalation, the lung volume expands as a result of the contraction of the diaphragm and intercostal muscles the muscles that are connected to the rib cage , thus expanding the thoracic cavity.
This decrease of pressure in the thoracic cavity relative to the environment makes the cavity pressure less than the atmospheric pressure. This pressure gradient between the atmosphere and the thoracic cavity allows air to rush into the lungs; inhalation occurs.
The resulting increase in volume is largely attributed to an increase in alveolar space because the bronchioles and bronchi are stiff structures that do not change in size. Inhalation and exhalation : The lungs, chest wall, and diaphragm are all involved in respiration, both a inhalation and b expiration. During this process, the chest wall expands out and away from the lungs.
The lungs are elastic; therefore, when air fills the lungs, the elastic recoil within the tissues of the lung exerts pressure back toward the interior of the lungs. These outward and inward forces compete to inflate and deflate the lung with every breath. Upon exhalation, the lungs recoil to force the air out of the lungs. The intercostal muscles relax, returning the chest wall to its original position.
During exhalation, the diaphragm also relaxes, moving higher into the thoracic cavity. This increases the pressure within the thoracic cavity relative to the environment. Air rushes out of the lungs due to the pressure gradient between the thoracic cavity and the atmosphere. This movement of air out of the lungs is classified as a passive event since there are no muscles contracting to expel the air. Each lung is surrounded by an invaginated sac. The layer of tissue that covers the lung and dips into spaces is called the visceral pleura.
A second layer of parietal pleura lines the interior of the thorax. The space between these layers, the intrapleural space, contains a small amount of fluid that protects the tissue by reducing the friction generated from rubbing the tissue layers together as the lungs contract and relax. If these layers of tissues become inflamed, this is categorized as pleurisy: a painful inflammation that increases the pressure within the thoracic cavity, reducing the volume of the lung.
Visceral pleura : A tissue layer called pleura surrounds the lung and interior of the thoracic cavity. Types of breathing in humans include eupnea, hyperpnea, diaphragmatic, and costal breathing; each requires slightly different processes.
There are different types, or modes, of breathing that require a slightly different process to allow inspiration and expiration. All mammals have lungs that are the main organs for breathing. During exhalation, the lungs expel air and lung volume decreases. The various types of breathing, specifically in humans, include:. During eupnea, also referred to as quiet breathing, the diaphragm and external intercostals must contract. As the diaphragm relaxes, air passively leaves the lungs.
This type of breathing is also known as deep breathing. Diaphragmatic breathing : Animation of a diaphragm exhaling and inhaling, demonstrating diaphragmatic breathing. During inhalation, the diaphragm is contracted which increases the volume of the lung cavity.
During exhalation, the diaphragm is relaxed which decreases the volume of the lung cavity. As the intercostal muscles relax, air passively leaves the lungs. This type of breathing is also known as shallow breathing. During hyperpnea, also known as forced breathing, inspiration and expiration both occur due to muscle contractions.
In addition to the contraction of the diaphragm and intercostal muscles, other accessory muscles must also contract. During forced inspiration, muscles of the neck, including the scalenes, contract and lift the thoracic wall, increasing lung volume.
During forced expiration, accessory muscles of the abdomen, including the obliques, contract, forcing abdominal organs upward against the diaphragm. This helps to push the diaphragm further into the thorax, pushing more air out. In addition, accessory muscles primarily the internal intercostals help to compress the rib cage, which also reduces the volume of the thoracic cavity.
In animals such as amphibians, there have been multiple ways of breathing that have evolved. In young amphibians, such as tadpoles that do not leave the water, gills are used to breathe. There are some amphibians that retain gills for life. As the tadpole grows, the gills disappear and lungs grow. These lungs are primitive and not as evolved as mammalian lungs.
Adult amphibians are lacking or have a reduced diaphragm, so breathing via lungs is forced. The other means of breathing for amphibians is diffusion across the skin. To aid this diffusion, amphibian skin must remain moist. Other animals, such as birds, must face a unique challenge with respect to breathing, which is that they fly.
Flying consumes a large amount of energy; therefore, birds require a lot of oxygen to aid their metabolic processes. They have evolved a respiratory system that supplies them with the oxygen needed to enable flying. Similar to mammals, birds have lungs, which are organs specialized for gas exchange. Smoking can also lead to lung cancer, the world's major cancer, which is diagnosed in 1. All rights reserved. Volcanic Fumes A climber in Russia's Kamchatka Peninsula wears a gas mask to keep noxious volcanic fumes out of his lungs.
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