Terminal Bronchi and Alveoli - Anatomy Pictures and Information Home > Respiratory System > Lungs and Respiratory System of the Chest > Terminal Bronchi and Alveoli Terminal Bronchi and Alveoli The terminal bronchi and alveoli are located at the very end of the conducting zone and the beginning of the respiratory zone in the respiratory system. The bronchi (or bronchus) are the air passages into the lungs that begin at the end of the trachea. There are two bronchi, one for each lung. The bronchus divide into smaller branches known as segmental bronchi, which divide again into bronchioles, and then again into terminal bronchioles. Each terminal bronchiole separates to create... Move up/down/left/right: Click compass arrows Rotate image: Click and drag in any direction, anywhere in the frame Identify objects: Click on them in the image 2D Interactive 3D Rotate & Zoom Change Anatomical System Change View Angle Full Terminal Bronchi and Alveoli Description [Continued from above] . . . respiratory bronchioles that have alveoli, which are small, balloon-like sacs at the end of the small air passages in the lungs (the bronchiole).

Oxygen is inhaled and absorbed into the bloodstream through the thin walls of each alveolus, by way of the pulmonary veins. Carbon dioxide from the pulmonary artery is exhaled as a waste product of the lungs. The greater the surface area the lungs have for gas exchange, the greater is their efficiency to absorb oxygen. The 700 million (or more) alveoli found in both lungs, if flattened out, would cover an area of some 50-100 square yards. This is approximately the size of a tennis court, and is all neatly folded and bundled into the chest cavity. Each alveolus has a wall that is only one cell thick. A capillary wall has about the same thickness. The distance between air and blood is about 1/1000th of a millimeter. The oxygen is transported by the red blood cells, which squeeze single file through the pulmonary capillaries. Red cells are packed with hemoglobin, or red pigment, that attracts the oxygen. Carbon dioxide is diffused in the same way back through the capillaries and alveolar walls to be exhaled.

The enormous surface area of the alveoli and the short diffusion distance between alveolar air and capillary blood quickly allows the blood to achieve equilibrium with gases of the alveolar air. This function is further increased by the fact that each alveolus is surrounded by a capillary network so extensive that it forms an almost continuous sheet of blood around each alveolus. Respiratory System | Interactive Anatomy Guide Female Full Respiratory System Description [Continued from above] . . . act as the functional units of the respiratory system by passing oxygen into the body and carbon dioxide out of the body. Finally, the muscles of respiration, including the diaphragm and intercostal muscles, work together to act as a pump, pushing air into and out of the lungs during breathing. Anatomy of the Respiratory System Nose and Nasal Cavity The nose and nasal cavity form the main external opening for the respiratory system and are the first section of the body’s airway—the respiratory tract through which air moves. The nose is a structure of the face made of cartilage, bone, muscle, and skin that supports and protects the anterior portion of the nasal cavity.

The nasal cavity is a hollow space within the nose and skull that is lined with hairs and mucus membrane. The function of the nasal cavity is to warm, moisturize, and filter air entering the body before it reaches the lungs. Hairs and mucus lining the nasal cavity help to trap dust, mold, pollen and other environmental contaminants before they can reach the inner portions of the body. Air exiting the body through the nose returns moisture and heat to the nasal cavity before being exhaled into the environment. Mouth The mouth, also known as the oral cavity , is the secondary external opening for the respiratory tract. Most normal breathing takes place through the nasal cavity, but the oral cavity can be used to supplement or replace the nasal cavity’s functions when needed. Because the pathway of air entering the body from the mouth is shorter than the pathway for air entering from the nose, the mouth does not warm and moisturize the air entering the lungs as well as the nose performs this function. The mouth also lacks the hairs and sticky mucus that filter air passing through the nasal cavity. The one advantage of breathing through the mouth is that its shorter distance and larger diameter allows more air to quickly enter the body.

Pharynx The pharynx, also known as the throat, is a muscular funnel that extends from the posterior end of the nasal cavity to the superior end of the esophagus and larynx. The pharynx is divided into 3 regions: the nasopharynx, oropharynx, and laryngopharynx. The nasopharynx is the superior region of the pharynx found in the posterior of the nasal cavity. Inhaled air from the nasal cavity passes into the nasopharynx and descends through the oropharynx, located in the posterior of the oral cavity. Air inhaled through the oral cavity enters the pharynx at the oropharynx . The inhaled air then descends into the laryngopharynx , where it is diverted into the opening of the larynx by the epiglottis. The epiglottis is a flap of elastic cartilage that acts as a switch between the trachea and the esophagus. Because the pharynx is also used to swallow food, the epiglottis ensures that air passes into the trachea by covering the opening to the esophagus.

During the process of swallowing, the epiglottis moves to cover the trachea to ensure that food enters the esophagus and to prevent choking. Larynx The larynx , also known as the voice box, is a short section of the airway that connects the laryngopharynx and the trachea. The larynx is located in the anterior portion of the neck, just inferior to the hyoid bone and superior to the trachea. Several cartilage structures make up the larynx and give it its structure. The epiglottis is one of the cartilage pieces of the larynx and serves as the cover of the larynx during swallowing. Inferior to the epiglottis is the thyroid cartilage , which is often referred to as the Adam’s apple as it is most commonly enlarged and visible in adult males. The thyroid holds open the anterior end of the larynx and protects the vocal folds. Inferior to the thyroid cartilage is the ring-shaped cricoid cartilage which holds the larynx open and supports its posterior end.

In addition to cartilage, the larynx contains special structures known as vocal folds, which allow the body to produce the sounds of speech and singing. The vocal folds are folds of mucous membrane that vibrate to produce vocal sounds. The tension and vibration speed of the vocal folds can be changed to change the pitch that they produce. Trachea The trachea, or windpipe, is a 5-inch long tube made of C-shaped hyaline cartilage rings lined with pseudostratified ciliated columnar epithelium. The trachea connects the larynx to the bronchi and allows air to pass through the neck and into the thorax. The rings of cartilage making up the trachea allow it to remain open to air at all times. The open end of the cartilage rings faces posteriorly toward the esophagus, allowing the esophagus to expand into the space occupied by the trachea to accommodate masses of food moving through the esophagus. The main function of the trachea is to provide a clear airway for air to enter and exit the lungs.

In addition, the epithelium lining the trachea produces mucus that traps dust and other contaminants and prevents it from reaching the lungs. Cilia on the surface of the epithelial cells move the mucus superiorly toward the pharynx where it can be swallowed and digested in the gastrointestinal tract. Bronchi and Bronchioles At the inferior end of the trachea, the airway splits into left and right branches known as the primary bronchi. The left and right bronchi run into each lung before branching off into smaller secondary bronchi. The secondary bronchi carry air into the lobes of the lungs—2 in the left lung and 3 in the right lung. The secondary bronchi in turn split into many smaller tertiary bronchi within each lobe. The tertiary bronchi split into many smaller bronchioles that spread throughout the lungs. Each bronchiole further splits into many smaller branches less than a millimeter in diameter called terminal bronchioles. Finally, the millions of tiny terminal bronchioles conduct air to the alveoli of the lungs. As the airway splits into the tree-like branches of the bronchi and bronchioles, the structure of the walls of the airway begins to change.

The primary bronchi contain many C-shaped cartilage rings that firmly hold the airway open and give the bronchi a cross-sectional shape like a flattened circle or a letter D. As the bronchi branch into secondary and tertiary bronchi, the cartilage becomes more widely spaced and more smooth muscle and elastin protein is found in the walls. The bronchioles differ from the structure of the bronchi in that they do not contain any cartilage at all. The presence of smooth muscles and elastin allow the smaller bronchi and bronchioles to be more flexible and contractile. The main function of the bronchi and bronchioles is to carry air from the trachea into the lungs. Smooth muscle tissue in their walls helps to regulate airflow into the lungs. When greater volumes of air are required by the body, such as during exercise, the smooth muscle relaxes to dilate the bronchi and bronchioles. The dilated airway provides less resistance to airflow and allows more air to pass into and out of the lungs. The smooth muscle fibers are able to contract during rest to prevent hyperventilation.

The bronchi and bronchioles also use the mucus and cilia of their epithelial lining to trap and move dust and other contaminants away from the lungs. Lungs The lungs are a pair of large, spongy organs found in the thorax lateral to the heart and superior to the diaphragm. Each lung is surrounded by a pleural membrane that provides the lung with space to expand as well as a negative pressure space relative to the body’s exterior. The negative pressure allows the lungs to passively fill with air as they relax. The left and right lungs are slightly different in size and shape due to the heart pointing to the left side of the body. The left lung is therefore slightly smaller than the right lung and is made up of 2 lobes while the right lung has 3 lobes. The interior of the lungs is made up of spongy tissues containing many capillaries and around 30 million tiny sacs known as alveoli . The alveoli are cup-shaped structures found at the end of the terminal bronchioles and surrounded by capillaries.

The alveoli are lined with thin simple squamous epithelium that allows air entering the alveoli to exchange its gases with the blood passing through the capillaries. Muscles of Respiration Surrounding the lungs are sets of muscles that are able to cause air to be inhaled or exhaled from the lungs. The principal muscle of respiration in the human body is the diaphragm, a thin sheet of skeletal muscle that forms the floor of the thorax. When the diaphragm contracts, it moves inferiorly a few inches into the abdominal cavity, expanding the space within the thoracic cavity and pulling air into the lungs. Relaxation of the diaphragm allows air to flow back out the lungs during exhalation. Between the ribs are many small intercostal muscles that assist the diaphragm with expanding and compressing the lungs. These muscles are divided into 2 groups: the internal intercostal muscles and the external intercostal muscles. The internal intercostal muscles are the deeper set of muscles and depress the ribs to compress the thoracic cavity and force air to be exhaled from the lungs.

The external intercostals are found superficial to the internal intercostals and function to elevate the ribs, expanding the volume of the thoracic cavity and causing air to be inhaled into the lungs. Physiology of the Respiratory System Pulmonary Ventilation Pulmonary ventilation is the process of moving air into and out of the lungs to facilitate gas exchange. The respiratory system uses both a negative pressure system and the contraction of muscles to achieve pulmonary ventilation. The negative pressure system of the respiratory system involves the establishment of a negative pressure gradient between the alveoli and the external atmosphere. The pleural membrane seals the lungs and maintains the lungs at a pressure slightly below that of the atmosphere when the lungs are at rest. This results in air following the pressure gradient and passively filling the lungs at rest. As the lungs fill with air, the pressure within the lungs rises until it matches the atmospheric pressure. At this point, more air can be inhaled by the contraction of the diaphragm and the external intercostal muscles, increasing the volume of the thorax and reducing the pressure of the lungs below that of the atmosphere again.

To exhale air, the diaphragm and external intercostal muscles relax while the internal intercostal muscles contract to reduce the volume of the thorax and increase the pressure within the thoracic cavity. The pressure gradient is now reversed, resulting in the exhalation of air until the pressures inside the lungs and outside of the body are equal. At this point, the elastic nature of the lungs causes them to recoil back to their resting volume, restoring the negative pressure gradient present during inhalation. External Respiration External respiration is the exchange of gases between the air filling the alveoli and the blood in the capillaries surrounding the walls of the alveoli. Air entering the lungs from the atmosphere has a higher partial pressure of oxygen and a lower partial pressure of carbon dioxide than does the blood in the capillaries. The difference in partial pressures causes the gases to diffuse passively along their pressure gradients from high to low pressure through the simple squamous epithelium lining of the alveoli. The net result of external respiration is the movement of oxygen from the air into the blood and the movement of carbon dioxide from the blood into the air.

The oxygen can then be transported to the body’s tissues while carbon dioxide is released into the atmosphere during exhalation. Internal Respiration Internal respiration is the exchange of gases between the blood in capillaries and the tissues of the body. Capillary blood has a higher partial pressure of oxygen and a lower partial pressure of carbon dioxide than the tissues through which it passes. The difference in partial pressures leads to the diffusion of gases along their pressure gradients from high to low pressure through the endothelium lining of the capillaries. The net result of internal respiration is the diffusion of oxygen into the tissues and the diffusion of carbon dioxide into the blood. Transportation of Gases The 2 major respiratory gases, oxygen and carbon dioxide, are transported through the body in the blood. Blood plasma has the ability to transport some dissolved oxygen and carbon dioxide, but most of the gases transported in the blood are bonded to transport molecules. Hemoglobin is an important transport molecule found in red blood cells that carries almost 99% of the oxygen in the blood. Hemoglobin can also carry a small amount of carbon dioxide from the tissues back to the lungs. However, the vast majority of carbon dioxide is carried in the plasma as bicarbonate ion.

When the partial pressure of carbon dioxide is high in the tissues, the enzyme carbonic anhydrase catalyzes a reaction between carbon dioxide and water to form carbonic acid. Carbonic acid then dissociates into hydrogen ion and bicarbonate ion. When the partial pressure of carbon dioxide is low in the lungs, the reactions reverse and carbon dioxide is liberated into the lungs to be exhaled. Homeostatic Control of Respiration Under normal resting conditions, the body maintains a quiet breathing rate and depth called eupnea. Eupnea is maintained until the body’s demand for oxygen and production of carbon dioxide rises due to greater exertion. Autonomic chemoreceptors in the body monitor the partial pressures of oxygen and carbon dioxide in the blood and send signals to the respiratory center of the brain stem. The respiratory center then adjusts the rate and depth of breathing to return the blood to its normal levels of gas partial pressures.

Prepared by Tim Taylor, Anatomy and Physiology Instructor THE RESPIRATORY SYSTEM THE RESPIRATORY SYSTEM Parts of the Respiratory System The Nose or Nasal Cavity ï¿½ï¿½ The Pharynx ï¿½ï¿½ï¿½ The Trachea ï¿½ï¿½ï¿½ The Lungs ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ Gas Exchange ï¿½ï¿½ï¿½ The Mechanism of Breathing ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ Breathing Disorders ï¿½ï¿½ Animation Links ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ The human respiratory system consists of the lungs and tubes associated with the lungs. It is located in the thorax or chest. The thorax is surrounded by the ribs.

The diaphragm forms the base of the thorax. ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ Contractions of the diaphragm and the intercostals muscle change the size of the thorax and, thus, cause air to move in and out of the lungs. ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ The main job of the respiratory system is to get oxygen into the body and get waste gases out of the body. It is the function of the respiratory system to transport gases to and from the circulatory system. Parts of the Respiratory System ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ THE HUMAN RESPIRATORY SYSTEM CONSISTS OF THE NOSE, NASAL CAVITY, PHARYNX, LARYNX, TRACHEA, SMALLER CONDUCTING PASSAGEWAYS (BRONCHI AND BRONCHIOLES), AND LUNGS.

The Nose or Nasal Cavity As air passes through the nasal cavities it is warmed and humidified, so that air that reaches the lungs is warmed and moist.ï¿½ The Nasal airways are lined with cilia and kept moist by mucous secretions. The combination of cilia and mucous helps to filter out solid particles from the air an Warm and moisten the air, which prevents damage to the delicate tissues that form the Respiratory System. The moisture in the nose helps to heat and humidify the air, increasing the amount of water vapour the air entering the lungs contains. This helps to keep the air entering the nose from drying out the lungs and other parts of our respiratory system. When air enters the respiratory system through the mouth, much less filtering is done. It is generally better to take in air through the nose. To review: he nose does the following: 1. Filters the air by the hairs and mucous in the nose 2. Moistens the air The Pharynx ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ The pharynx is also called the throat.

As we saw in the digestive system, the epiglottis closes off the trachea when we swallow. Below the epiglottis is the larynx or voice box. This contains 2 vocal cords, which vibrate when air passes by them. With our tongue and lips we convert these vibrations into speech. The area at the top of the trachea, which contains the larynx, is called the glottis. The Trachea ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ The trachea or windpipe is made of muscle and elastic fibres with rings of cartilage. The cartilage prevents the tubes of the trachea from collapsing. The trachea is divided or branched into bronchi and then into smaller bronchioles. The bronchioles branch off into alveoli. The alveoli will be discussed later.

ï¿½ï¿½ ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ These tubes are lined with mucous-secreting cells and tiny hairs called cilia. The mucous traps bacteria, dust and viruses. The cilia beat and create an upward current. This moves the mucous up and into the oesophagus. Here it goes to the stomach. When we clear our throats we force the mucous away from our vocal cords. This is often called coughing. It is used to get rid of irritants and excess mucous from our respiratory system. The Lungs ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ The lungs are spongy structure where the exchange of gases takes place. Each lung is surrounded by a pair of pleural membranes. Between the membranes is pleural fluid, which reduces friction while breathing. The bronchi are divided into about a million bronchioles. The ends of the bronchioles are hollow air sacs called alveoli. There are over 700 million alveoli in the lungs.

This greatly increases the surface area through which gas exchange occurs. Surrounding the alveoli are capillaries. The lungs give up their oxygen to the capillaries through the alveoli. Likewise, carbon dioxide is taken from the capillaries and into the alveoli. ï¿½ Gas Exchange ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ Body cells use the inhaled oxygen gotten from the alveoli of the lungs. In turn, they produce carbon dioxide and water, which is taken to the alveoli and then exhaled. These exchanges occur as a result of diffusion. In each case the materials move from an area of high concentration to an area of lower concentration.

ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ Here, the blood flows from the heart to the lungs.ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ Here the blood flows from the lungs to the body cells.

The alveoli take in the water and the carbon dioxideï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ The body cells take in the oxygen and give off the and give off the oxygen.ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ carbon dioxide and the water.

Click here to see an animation of this gas exchange ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ The alveoli are well suited for the important job they have. There are about 300,000,000 alveoli per lung! That means there is a great surface area for gas exchange. Also, the walls of the alveoli as well as the capillaries are very thin so that the gases can diffuse readily. ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ When the blood picks up the diffused gases the gases are carried to their destinations. Most of the oxygen is carried by the haemoglobin in the red blood cells with only a small % dissolved in the plasma. Carbon dioxide and water are carried in the plasma of the blood. The following chart compares the content of air before as it is inhaled (Inspired Air) and as it is exhaled (Expired Air). Inspired and Expired Air Comparison Gas + % Back to Top The Mechanism of Breathing Inspiration or inhalation is said to be an active process because it involves muscle contraction.

The diaphragm and intercostal muscles contract. The contracting diaphragm flattens and stretches the elastic lungs downward. The contracting intercostals pull the ribcage up and out causing the elastic lungs to stretch. The expanding lungs cause the air inside to expand (a gas will always fill its container). The expansion of air causes a drop in air pressure in the lungs. The air in the lungs is at a lower pressure than the air outside. Air flows from higher to lower pressure so air flows into the lungs from outside. Expiration or exhalation is said to be a passive process because it does not involve muscle contraction. The diaphragm and the intercostal muscles relax. The deforming force on the elastic lungs has been removed. The lungs recoil elastically reducing their volume ï¿½ a passive process. The volume of air in the lungs decreases causing an increase in the air pressure. The air in the lungs is at a higher pressure than the air outside. Air flows from higher to lower pressure so the air flows out of the lungs. The elastic recoil of the lungs pulls up the adhering diaphragm and drags in the adhering ribcage. Breathing is normally under unconscious control.

We donï¿½t have to think about breathing. Exercise increases the rate of breathing. The brain detects a large increase in carbon dioxide and increases the rate of breathing. Now, exhalation, which is normally passive, becomes active. Other times when we control our breathing rate is in speaking, singing, or swimming. Breathing is always controlled by the brainï¿½s detection of carbon dioxide in the blood. When carbon dioxide is in the blood the pH of the blood is slightly lowered. The brain detects this slight drop and sends impulses to the diaphragm and intercostal muscles. Thus, our breathing mechanism is controlled by rising levels of carbon dioxide, not low levels of oxygen. Just as the level of carbon dioxide controls the stomata opening in leaves it also controls our breathing. Breathing Disorders Asthma is a breathing disorder. Its symptoms include coughing, wheezing, tightness of chest and breathlessness. It is caused by an allergic reaction to materials in the environment such as pollen, cigarette smoke, house dust and pet dander. More recently scientists have found a link between stress and anxiety with the onset of asthma.

Asthma is a chronic ailment in which inflammation of the airways, or bronchi, affects the way air enters and leaves the lungs, thereby disrupting breathing. When allergens or irritants come into contact with the inflamed airways, the already sensitive airways tighten and narrow, making it difficult for the person to breathe. Progressively severe symptoms can lead to an asthma attack. In asthma attacks, the overproduction of mucus lining the airways further narrows the airways, limiting oxygen intake and making it more difficult to breathe. To prevent asthma the allergen must be identified and avoided. Also, in the case of stress, the stress must be alleviated. The treatment of asthma is usually by Inhalers. These devices (sometimes called 'puffers') contain a gas that will propel the correct dose of medication when the top is pressed down. This is inhaled into the airways. There are two basic categories of inhaler medicines that are used for asthma: relievers - which treat the symptoms and preventers - which can prevent the symptoms.

ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ï¿½ The role of Alveoli in the respiratory system Home / Training Zone / The Human Body / Respiratory System / Alveoli Alveoli Part of

 the respiratory system, these tiny alveoli have a key role in the movement of oxygen and carbon dioxide.

Role in the respiratory system. The final branches of the respiratory tree, alveoli are where oxygen from the air enters your blood, and carbon dioxide from your body is expelled back into the air. How they work. Air enters the body through the nose or mouth, passes through the larynx, down the trachea, and into our lungs. Once it is in your lungs, air goes through a maze of smaller and smaller bronchial tubes until it reaches clusters of tiny sacs the alveoli. In appearance they are somewhat like bunches of grapes. Size and where they live. These alveoli are tiny, but your lungs are simply packed with them an estimated three hundred million per lung, all required to ensure that your body gets the oxygen it needs. Once it is in your lungs, the blood has to get into your blood. The alveoli are the primary gas exchange units of the lung. Quite simply, they are the point where the gas-blood barrier is thin enough to permit rapid gas exchange. To get into the blood, oxygen is diffused through the alveolar epithelium, a thin interstitial space, and the capillary endothelium. Role also has to be reversed.

That is only half the process of course this process also has to work in reverse in order to allow CO2, a waste product carried by the blood, to be expelled back into the lungs, and thus out of the body when we exhale. Human Respiratory System and Lungs; How They Work Clearing the Air You usually don't even notice it, but twelve to twenty times per minute, day after day, you breathe -- thanks to your body's respiratory system . Your lungs expand and contract, supplying life-sustaining oxygen to your body and removing from it, a waste product called carbon dioxide . The Act of Breathing Breathing starts at the nose and mouth . You inhale air into your nose or mouth , and it travels down the back of your throat and into your windpipe, or trachea . Your trachea then divides into air passages called bronchial tubes. For your lungs to perform their best, these airways need to be open during inhalation and exhalation and free from inflammation or swelling and excess or abnormal amounts of mucus. As the bronchial tubes pass through the lungs, they divide into smaller air passages called bronchioles.

The bronchioles end in tiny balloon-like air sacs called alveoli. Your body has over 300 million alveoli. The alveoli are surrounded by a mesh of tiny blood vessels called capillaries. Here, oxygen from the inhaled air passes through the alveoli walls and into the blood . After absorbing oxygen, the blood leaves the lungs and is carried to your heart . Your heart then pumps it through your body to provide oxygen to the cells of your tissues and organs. As the cells use the oxygen, carbon dioxide is produced and absorbed into the blood. Your blood then carries the carbon dioxide back to your lungs, where it is removed from the body when you exhale. The Diaphragm's Role in Breathing Inhalation and exhalation are the processes by which the body brings in oxygen and expels carbon dioxide. The breathing process is aided by a large dome-shaped muscle under the lungs called the diaphragm. When you breathe in, the diaphragm contracts downward, creating a vacuum that causes a rush of fresh air into the lungs. The opposite occurs with exhalation, where the diaphragm relaxes upwards, pushing on the lungs, allowing them to deflate.

Clearing the Air The respiratory system has built-in methods to prevent harmful substances in the air from entering the lungs. Hairs in your nose help filter out large particles. Microscopic hairs, called cilia, are found along your air passages and move in a sweeping motion to keep the air passages clean. But if harmful substances, such as cigarette smoke, are inhaled, the cilia stop functioning properly, causing health problems like bronchitis . Mucus produced by cells in the trachea and bronchial tubes keeps air passages moist and aids in stopping dust, bacteria and viruses, allergy -causing substances, and other substances from entering the lungs. Impurities that do reach the deeper parts of the lungs can often be moved up via mucous and coughed out or swallowed. WebMD Medical Reference Alveoli: Function, Definition & Sacs - Video & Lesson Transcript | Study.com Alveoli: Function, Definition & Sacs Watch short & fun videos Start Your Free Trial Today An error occurred trying to load this video. Try refreshing the page, or contact customer support. You must create an account to continue watching Register for a free trial Are you a student or a teacher?

I am a student Start Your Free Trial To Continue Watching As a member, you'll also get unlimited access to over lessons in math, English, science, history, and more. Plus, get practice tests, quizzes, and personalized coaching to help you succeed. Coming up next: Stomata of Plants: Function, Definition & Structure You're on a roll. Keep up the good work! Your next lesson will play in 10 seconds 0:01 Alveoli Defined 2:27 Alveoli In our Anatomy 3:03 Function of Alveoli Add to Add to Add to Want to watch this again later? Log in or sign up to add this lesson to a Custom Course. Custom Courses are courses that you create from Study.com lessons. Use them just like other courses to track progress, access quizzes and exams, and share content. Teachers Organize and share selected lessons with your class. Make planning easier by creating your own custom course. Students Create a new course from any lesson page or your dashboard. From any lesson page: Click "Add to" located below the video player and follow the prompts to name your course and save your lesson.

From your dashboard: Click on the "Custom Courses" tab, then click "Create course". Next, go to any lesson page and begin adding lessons. Edit your Custom Course directly from your dashboard. Personalize: Name your Custom Course and add an optional description or learning objective. Organize: Create chapters to group lesson within your course. Remove and reorder chapters and lessons at any time. Share your Custom Course or assign lessons and chapters. Teacher Edition: Share or assign lessons and chapters by clicking the "Teacher" tab on the lesson or chapter page you want to assign. Students' quiz scores and video views will be trackable in your "Teacher" tab. Premium Edition: You can share your Custom Course by copying and pasting the course URL. Only Study.com members will be able to access the entire course. Create an account to start this course today Try it free for 5 days! Instructor: Wendy McDougal Wendy has taught high school Biology and has a master's degree in education. Alveoli are tiny sacs within our lungs that allow oxygen and carbon dioxide to move between the lungs and bloodstream. Learn more about how they function and quiz your knowledge at the end.

Alveoli Defined Our bodies perform certain functions every second of the day and night without our conscious awareness. For example, breathing is a job that our body does for us, whether we are asleep or awake, conscious or unconscious. But what is the actual purpose of breathing, other than merely keeping us alive? You probably already know that it has to do with taking in oxygen and getting rid of carbon dioxide. In this lesson, we will learn about tiny organs that help our body parts get the oxygen that we breathe in and get rid of the carbon dioxide we don't need. These organs are called alveoli. The Respiratory System Our bodies need oxygen in order to live. We get our oxygen from the air we breathe. However, in order for our bodies to use this oxygen, it must get from our lungs into our bloodstream. This will eventually happen in the alveoli; but we will discuss that a little later. To understand alveoli, we first need to examine the major parts of the respiratory system. Respiratory System Our respiratory system includes structures involved in our breathing. When you take a breath, air is drawn into your mouth and nose and into a tube called the trachea, or windpipe.

Let's follow the path of the air as it travels through the trachea and into your lungs. The Bronchial Tree As we head into the lungs, the trachea branches into two main sections, each called a bronchus. There is a right primary bronchus that goes into the right lung, and a left primary bronchus that goes into the left lung. Each of these bronchi (plural for bronchus) then branch into more bronchi. Those, in turn, branch into smaller tubes called bronchioles. All of this branching eventually results in a structure that truly resembles an upside-down tree. The trachea is the trunk, with all of the branches coming from it. For that reason, it is known as the bronchial tree. Although this branching does not continue forever, it does happen about 25 times after the first branching of the trachea. The last bronchioles divide into what are called respiratory bronchioles, each of which divide into tiny openings called alveolar ducts. You can imagine how each tube has gotten smaller and smaller as it has branched. By the time we reach the alveoli, the tubes are microscopic - and there are millions of them!

Alveoli In Our Anatomy At the end of each of the many tiny branches of our bronchial tree, we find openings to microscopic sacs. Each little sac is an alveolus, singular for alveoli. There may be several alveoli coming from one duct, forming a little clump. These groups of alveoli somewhat resemble a cluster of grapes that are all attached. It is in the alveoli that one of the most important transfers in our entire body takes place. It is here that the respiratory system comes into direct contact with the circulatory system, or blood vessels. Alveoli and Capillaries Function of Alveoli We breathe in oxygen so that parts of our body can use it for many different cellular functions. But we must somehow get the oxygen from our lungs into our bloodstream, so it can be transported to the many places it is needed. Likewise, our bodies produce carbon dioxide as a waste product. It must be exhaled from our body, but must get from the bloodstream to our lungs. It is the alveoli that are responsible for this transfer of gases. But how, exactly, does this work?

× Lungs and Respiratory System Lungs and Respiratory System Pulmones y el sistema respiratorio Whether you're wide awake and getting ready for a big date or asleep during your most snooze-worthy afternoon class, you don't have to think about breathing. It's so important to life that it happens automatically. If you didn't breathe, you couldn't live. Lungs & Respiratory System Basics Each day we breathe about 20,000 times. All of this breathing couldn't happen without help from the respiratory system, which includes the nose, throat, voice box, windpipe, and lungs. With each breath, you take in air through your nostrils and mouth, and your lungs fill up and empty out. As air is inhaled, the mucous membranes of the nose and mouth warm and humidify the air. Although we can't see it, the air we breathe is made up of several gases. Oxygen is the most important for keeping us alive because body cells need it for energy and growth. Without oxygen, the body's cells would die. Carbon dioxide is the waste gas that is produced when carbon is combined with oxygen as part of the body's energy-making processes.

The lungs and respiratory system allow oxygen in the air to be taken into the body, while also enabling the body to get rid of carbon dioxide in the air breathed out. Respiration is the term for the exchange of oxygen from the environment for carbon dioxide from the body's cells. The process of taking air into the lungs is called inhalation or inspiration, and the process of breathing it out is called exhalation or expiration. Even if the air you breathe is dirty or polluted, your respiratory system filters out foreign matter and organisms that enter through the nose and mouth. Pollutants are breathed or coughed out, destroyed by digestive juices, or eaten by macrophages, a type of blood cell that patrols the body looking for germs to destroy. Tiny hairs called cilia (pronounced: SIL-ee-uh) protect the nasal passageways and other parts of the respiratory tract, filtering out dust and other particles that enter the nose with the breathed air. As air is inhaled, the cilia move back and forth, pushing any foreign matter (like dust) either toward the nostrils, where it is blown out, or toward the pharynx, where it travels through the digestive system and out with the rest of the body's waste.

continue What They Do The two openings of the airway (the nasal cavity and the mouth) meet at the pharynx (pronounced: FAR-inks), or throat, at the back of the nose and mouth. The pharynx is part of the digestive system as well as the respiratory system because it carries both food and air. At the bottom of the pharynx, the pathway for both food and air divides in two. One passageway is for food (the esophagus, pronounced: ih-SAH-fuh-gus, which leads to the stomach) and the other for air. The epiglottis (pronounced: eh-pih-GLAH-tus), a small flap of tissue, covers the air-only passage when we swallow, keeping food and liquid from going into our lungs. The larynx (pronounced: LAR-inks), or voice box, is the uppermost part of the air-only passage. This short tube contains a pair of vocal cords, which vibrate to make sounds. The trachea (pronounced: TRAY-kee-uh), or windpipe, extends downward from the base of the larynx. It lies partly in the neck and partly in the chest cavity.

The walls of the trachea are strengthened by stiff rings of cartilage to keep it open so air can flow through on its way to the lungs. The trachea is also lined with cilia, which sweep fluids and foreign particles out of the airway so that they stay out of the lungs. At its bottom end, the trachea divides into left and right air tubes called bronchi (pronounced: BRAHN-kye), which connect to the lungs. Within the lungs, the bronchi branch into smaller bronchi and even smaller tubes called bronchioles (pronounced: BRAHN-kee-olz). Bronchioles, which are as thin as a strand of hair, end in tiny air sacs called alveoli (pronounced: al-VEE-oh-lye). Each of us has hundreds of millions of alveoli in our lungs — enough to cover a tennis court if they were spread out on the ground. The alveoli are where the exchange of oxygen and carbon dioxide takes place. With each inhalation, air fills a large portion of the millions of alveoli.

In a process called diffusion (pronounced: dih-FYOO-zhun), oxygen moves from the alveoli to the blood through the capillaries (tiny blood vessels, pronounced: KAP-uh-lair-eez) that line the alveolar walls. Once in the bloodstream, oxygen gets picked up by a molecule called hemoglobin (pronounced: HEE-muh-glo-bun) in the red blood cells. This oxygen-rich blood then flows back to the heart, which pumps it through the arteries to oxygen-hungry tissues throughout the body. In the tiny capillaries of the body tissues, oxygen is freed from the hemoglobin and moves into the cells. Carbon dioxide, which is produced during the process of diffusion, moves out of these cells into the capillaries, where most of it is dissolved in the plasma of the blood. Blood rich in carbon dioxide then returns to the heart via the veins. From the heart, this blood is pumped to the lungs, where carbon dioxide passes into the alveoli to be exhaled. The lungs also contain elastic tissues that allow them to inflate and deflate without losing shape and are encased by a thin lining called the pleura (pronounced: PLUR-uh).

This network of alveoli, bronchioles, and bronchi is known as the bronchial tree. The chest cavity, or thorax (pronounced: THOR-aks), is the airtight box that houses the bronchial tree, lungs, heart, and other structures. The top and sides of the thorax are formed by the ribs and attached muscles, and the bottom by a large muscle called the diaphragm. The chest walls form a protective cage around the lungs and other contents of the chest cavity. The diaphragm (pronounced: DYE-uh-fram), which separates the chest from the abdomen, plays a lead role in breathing. When we breathe out, the diaphragm moves upward, forcing the chest cavity to get smaller and pushing the gases in the lungs up and out of the nose and mouth. When we breathe in, the diaphragm moves downward toward the abdomen, and the rib muscles pull the ribs upward and outward, enlarging the chest cavity and pulling air in through the nose or mouth. Air pressure in the chest cavity and lungs is reduced, and because gas flows from high pressure to low, air from the environment flows through the nose or mouth into the lungs.

As we exhale, the diaphragm moves upward and the chest wall muscles relax, causing the chest cavity to contract. Air pressure in the lungs rises, so air flows from the lungs and up and out of respiratory system through the nose or mouth. previous continue Things That Can Go Wrong Many factors — including genetics, pollutants and irritants, and infectious diseases — can affect the health of your lungs and respiratory system and cause respiratory problems. Problems of the respiratory system that can affect people during their teen years include: Asthma . More than 20 million people have asthma in the United States, and it's the #1 reason that kids and teens chronically miss school. Asthma is a long-term, inflammatory lung disease that causes airways to tighten and narrow when a person with the condition comes into contact with irritants such as cigarette smoke, dust, or pet dander. Bronchitis . Although bronchitis doesn't affect most teens, it can affect those who smoke. In bronchitis, the membranes lining the larger bronchial tubes become inflamed and an excessive amount of mucus is produced. The person with bronchitis develops a bad cough to get rid of the mucus. Common cold .

Colds are caused by over 200 different viruses that cause inflammation in the upper respiratory tract. The common cold is the most common respiratory infection. Symptoms may include a mild fever, cough, headache, runny nose, sneezing, and sore throat. Cough. A cough is a symptom of an illness, not an illness itself. There are many different types of cough and many different causes, ranging from not-so-serious to life threatening. Some of the more common causes affecting kids and teens are the common cold, asthma, sinusitis, seasonal allergies, and pneumonia. Cystic fibrosis (CF) . CF is an inherited disease affecting the lungs. CF causes mucus in the body to be abnormally thick and sticky. The mucus can clog the airways in the lungs and make a person more likely to get bacterial infections. Pneumonia . Pneumonia is an inflammation of the lungs, which usually occurs because of infection with a bacteria or virus. Pneumonia causes fever, inflammation of lung tissue, and makes breathing difficult because the lungs have to work harder to transfer oxygen into the bloodstream and remove carbon dioxide from the blood.

Common causes of pneumonia are influenza and infection with the bacterium Streptococcus pneumoniae. Although some respiratory diseases like asthma or cystic fibrosis can't be prevented, you can prevent many chronic lung and respiratory illnesses by avoiding smoking, staying away from pollutants and irritants, washing your hands often to avoid infection, and getting regular medical checkups. The Lungs (Human Anatomy): Picture, Function, Definition, Conditions Human Anatomy Picture of the Lungs © 2014 WebMD, LLC. All rights reserved. The lungs are a pair of spongy, air-filled organs located on either side of the chest (thorax). The trachea (windpipe) conducts inhaled air into the lungs through its tubular branches, called bronchi. The bronchi then divide into smaller and smaller branches (bronchioles), finally becoming microscopic. The bronchioles eventually end in clusters of microscopic air sacs called alveoli. In the alveoli, oxygen from the air is absorbed into the blood . Carbon dioxide , a waste product of metabolism , travels from the blood to the alveoli, where it can be exhaled.

Between the alveoli is a thin layer of cells called the interstitium, which contains blood vessels and cells that help support the alveoli. The lungs are covered by a thin tissue layer called the pleura. The same kind of thin tissue lines the inside of the chest cavity -- also called pleura. A thin layer of fluid acts as a lubricant allowing the lungs to slip smoothly as they expand and contract with each breath. Lung Conditions Chronic obstructive pulmonary disease ( COPD ): Damage to the lungs results in difficulty blowing air out, causing shortness of breath. Smoking is by far the most common cause of COPD. Emphysema : A form of COPD usually caused by smoking . The fragile walls between the lungs' air sacs (alveoli) are damaged, trapping air in the lungs and making breathing difficult. Chronic bronchitis : Repeated, frequent episodes of productive cough, usually caused by smoking . Breathing also becomes difficult in this form of COPD. Pneumonia : Infection in one or both lungs. Bacteria, especially Streptococcus pneumoniae, are the most common cause.

Asthma : The lungs' airways (bronchi) become inflamed and can spasm, causing shortness of breath and wheezing . Allergies , viral infections , or air pollution often trigger asthma symptoms . Acute bronchitis : An infection of the lungs' large airways (bronchi), usually caused by a virus. Cough is the main symptom of acute bronchitis . Pulmonary fibrosis : A form of interstitial lung disease . The interstitium (walls between air sacs) become scarred, making the lungs stiff and causing shortness of breath. Sarcoidosis : Tiny areas of inflammation can affect all organs in the body, with the lungs involved most of the time. The symptoms are usually mild; sarcoidosis is usually found when X-rays are done for other reasons. Obesity hypoventilation syndrome: Extra weight makes it difficult to expand the chest when breathing. This can lead to long-term breathing problems . Pleural effusion : Fluid builds up in the normally tiny space between the lung and the inside of the chest wall (the pleural space). If large, pleural effusions can cause problems with breathing.

Pleurisy : Inflammation of the lining of the lung (pleura), which often causes pain when breathing in. Autoimmune conditions, infections, or a pulmonary embolism may cause pleurisy . Bronchiectasis: The airways (bronchi) become inflamed and expand abnormally, usually after repeated infections. Coughing , with large amounts of mucus, is the main symptom of bronchiectasis. Lymphangioleiomyomatosis ( LAM ): A rare condition in which cysts form throughout the lungs, causing breathing problems similar to emphysema . LAM occurs almost exclusively in women of childbearing age. Cystic fibrosis : A genetic condition in which mucus does not clear easily from the airways. The excess mucus causes repeated episodes of bronchitis and pneumonia throughout life. Interstitial lung disease : A collection of conditions in which the interstitium (lining between the air sacs) becomes diseased. Fibrosis (scarring) of the interstitium eventually results, if the process can't be stopped. Lung cancer : Cancer may affect almost any part of the lung. Most lung cancer is caused by smoking .

Your Lungs & Respiratory System Your Lungs & Respiratory System What's something that you do all day, every day, no matter where you are or who you're with? (a) think about what's for lunch tomorrow (b) put your finger in your nose (c) hum your favorite song (d) breathe It's possible that some kids could say (a) or (c) or that others might even say — yikes! — (b). But every single person in the world has to say (d). Breathing air is necessary for keeping humans (and many animals) alive. And the two parts that are large and in charge when it comes to breathing? If you guessed your lungs, you're right! Your lungs make up one of the largest organs in your body, and they work with your respiratory system to allow you to take in fresh air, get rid of stale air, and even talk. Let's take a tour of the lungs! Locate Those Lungs Your lungs are in your chest, and they are so large that they take up most of the space in there. You have two lungs, but they aren't the same size the way your eyes or nostrils are.

Instead, the lung on the left side of your body is a bit smaller than the lung on the right. This extra space on the left leaves room for your heart. Your lungs are protected by your rib cage, which is made up of 12 sets of ribs. These ribs are connected to your spine in your back and go around your lungs to keep them safe. Beneath the lungs is the diaphragm (say: DY-uh-fram), a dome-shaped muscle that works with your lungs to allow you to inhale (breathe in) and exhale (breathe out) air. You can't see your lungs, but it's easy to feel them in action: Put your hands on your chest and breathe in very deeply. You will feel your chest getting slightly bigger. Now breathe out the air, and feel your chest return to its regular size. You've just felt the power of your lungs! continue A Look Inside the Lungs From the outside, lungs are pink and a bit squishy, like a sponge. But the inside contains the real lowdown on the lungs! At the bottom of the trachea (say: TRAY-kee-uh), or windpipe, there are two large tubes.

These tubes are called the main stem bronchi (say: BRONG-kye), and one heads left into the left lung, while the other heads right into the right lung. Each main stem bronchus (say: BRONG-kuss) — the name for just one of the bronchi — then branches off into tubes, or bronchi, that get smaller and even smaller still, like branches on a big tree. The tiniest tubes are called bronchioles (say: BRONG-kee-oles), and there are about 30,000 of them in each lung. Each bronchiole is about the same thickness as a hair. At the end of each bronchiole is a special area that leads into clumps of teeny tiny air sacs called alveoli (say: al-VEE-oh-lie). There are about 600 million alveoli in your lungs and if you stretched them out, they would cover an entire tennis court. Now that's a load of alveoli!

Each alveolus (say: al-VEE-oh-luss) — what we call just one of the alveoli — has a mesh-like covering of very small blood vessels called capillaries (say: CAP-ill-er-ees). These capillaries are so tiny that the cells in your blood need to line up single file just to march through them. All About Inhaling When you're walking your dog, cleaning your room, or spiking a volleyball, you probably don't think about inhaling (breathing in) — you've got other things on your mind! But every time you inhale air, dozens of body parts work together to help get that air in there without you ever thinking about it. As you breathe in, your diaphragm contracts and flattens out. This allows it to move down, so your lungs have more room to grow larger as they fill up with air. "Move over, diaphragm, I'm filling up!" is what your lungs would say. And the diaphragm isn't the only part that gives your lungs the room they need. Your rib muscles also lift the ribs up and outward to give the lungs more space.

At the same time, you inhale air through your mouth and nose, and the air heads down your trachea, or windpipe. On the way down the windpipe, tiny hairs called cilia (say: SILL-ee-uh) move gently to keep mucus and dirt out of the lungs. The air then goes through the series of branches in your lungs, through the bronchi and the bronchioles. previous continue Thank You, Alveoli! The air finally ends up in the 600 million alveoli. As these millions of alveoli fill up with air, the lungs get bigger. Remember that experiment where you felt your lungs get larger? Well, you were really feeling the power of those awesome alveoli! It's the alveoli that allow oxygen from the air to pass into your blood. All the cells in the body need oxygen every minute of the day. Oxygen passes through the walls of each alveolus into the tiny capillaries that surround it. The oxygen enters the blood in the tiny capillaries, hitching a ride on red blood cells and traveling through layers of blood vessels to the heart.

The heart then sends the oxygenated (filled with oxygen) blood out to all the cells in the body. Waiting to Exhale When it's time to exhale (breathe out), everything happens in reverse: Now it's the diaphragm's turn to say, "Move it!" Your diaphragm relaxes and moves up, pushing air out of the lungs. Your rib muscles become relaxed, and your ribs move in again, creating a smaller space in your chest. By now your cells have used the oxygen they need, and your blood is carrying carbon dioxide and other wastes that must leave your body. The blood comes back through the capillaries and the wastes enter the alveoli. Then you breathe them out in the reverse order of how they came in — the air goes through the bronchioles, out the bronchi, out the trachea, and finally out through your mouth and nose. The air that you breathe out not only contains wastes and carbon dioxide, but it's warm, too! As air travels through your body, it picks up heat along the way. You can feel this heat by putting your hand in front of your mouth or nose as you breathe out.

What is the temperature of the air that comes out of your mouth or nose? With all this movement, you might be wondering why things don't get stuck as the lungs fill and empty! Luckily, your lungs are covered by two really slick special layers called pleural (say: PLOO-ral) membranes. These membranes are separated by a fluid that allows them to slide around easily while you inhale and exhale. previous continue Time for Talk Your lungs are important for breathing . . . and also for talking! Above the trachea (windpipe) is the larynx (say: LAIR-inks), which is sometimes called the voice box. Across the voice box are two tiny ridges called vocal cords, which open and close to make sounds. When you exhale air from the lungs, it comes through the trachea and larynx and reaches the vocal cords. If the vocal cords are closed and the air flows between them, the vocal cords vibrate and a sound is made. The amount of air you blow out from your lungs determines how loud a sound will be and how long you can make the sound.

Try inhaling very deeply and saying the names of all the kids in your class — how far can you get without taking the next breath? The next time you're outside, try shouting and see what happens — shouting requires lots of air, so you'll need to breathe in more frequently than you would if you were only saying the words. Experiment with different sounds and the air it takes to make them — when you giggle, you let out your breath in short bits, but when you burp , you let swallowed air in your stomach out in one long one! When you hiccup, it's because the diaphragm moves in a funny way that causes you to breathe in air suddenly, and that air hits your vocal cords when you're not ready. Love Your Lungs Your lungs are amazing. They allow you to breathe, talk to your friend, shout at a game, sing, laugh, cry, and more! And speaking of a game, your lungs even work with your brain to help you inhale and exhale a larger amount of air at a more rapid rate when you're running a mile — all without you even thinking about it once.

Keeping your lungs looking and feeling healthy is a smart idea, and the best way to keep your lungs pink and healthy is not to smoke. Smoking isn't good for any part of your body, and your lungs especially hate it. Cigarette smoke damages the cilia in the trachea so they can no longer move to keep dirt and other substances out of the lungs. Your alveoli get hurt too, because the chemicals in cigarette smoke can cause the walls of the delicate alveoli to break down, making it much harder to breathe. Finally, cigarette smoke can damage the cells of the lungs so much that the healthy cells go away, only to be replaced by cancer cells. Lungs are normally tough and strong, but when it comes to cigarettes, they can be hurt easily — and it's often very difficult or impossible to make them better. If you need to work with chemicals in an art or shop class, be sure to wear a protective mask to keep chemical fumes from entering your lungs. You can also show your love for your lungs by exercising! Exercise is good for every part of your body, and especially for your lungs and heart.

When you take part in vigorous exercise (like biking, running, or swimming, for example), your lungs require more air to give your cells the extra oxygen they need. As you breathe more deeply and take in more air, your lungs become stronger and better at supplying your body with the air it needs to succeed. Keep your lungs healthy and they will thank you for life!

Question: Alveoli are found in which part of the body?
Answer: Lungs