In humans, respiratory tract is part of the anatomy of the respiratory system involved with the respiratory process. Air is inhaled through the nose or mouth. In the nasal cavity, the mucous membrane layer acts as a filter and trap of pollutants and other harmful substances found in the air. Furthermore, the air moves into the pharynx, a portion containing the junction between the esophagus and the larynx. The opening of the larynx has a special cartilage flap, epiglottis, which opens to allow inlet air but closes to prevent food from moving into the airway.
From the larynx, the air moves into the trachea and descends to a branched intersection which forms the primary and left (left) bronchius. Each of these bronchial branches becomes a secondary bronchus (lobar) that branches off into the tertiary bronchus (segmental) which branches into smaller airways called bronchioles which eventually connect with a small special structure called alveoli that functions in gas exchange.
The lungs located in the thoracic cavity, protected from physical damage by the ribs. At the base of the lung is a skeletal muscle sheet called a diaphragm. The diaphragm separates the lungs from the stomach and intestines. The diaphragm is also the major respiratory muscle involved in breathing, and is controlled by the sympathetic nervous system.
The lungs are encased in a serous membrane that folds on itself to form a pleurae - a double layer protective barrier. Deep visceral pleura covers the surface of the lung, and the outer parietal pleura is attached to the inner surface of the thoracic cavity. The pleurae surrounds a cavity called a pleural cavity containing pleural fluid. This fluid is used to reduce the amount of friction experienced by the lungs during breathing.
Video Respiratory tract
Structure
Respiratory channel is divided into upper air channel and lower air channel . The upper airway or upper respiratory tract includes the nasal and nasal passages, paranasal sinuses, pharynx, and laryngeal parts above the vocal cords (rope). The lower airway or lower respiratory tract includes the laryngeal part below the vocal folds, the trachea, the bronchus, and the bronchioles. The lungs may be inserted in the lower respiratory tract or as separate entities and include respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli.
The respiratory tract can also be divided into conductor and respiratory zones zones, based on differences in gas transport or converting them.
The conduction zone includes structures outside the lungs - nose, pharynx, larynx, and trachea, and structures within the lungs - bronchus, bronchioles, and terminal bronchioles. The conduction zones inhale filtered, warmed, and moistened air, into the lungs. This is the 1st through the 16th division of the respiratory tract. The conduction zone of most of the respiratory passages conducts gas in and out of the lungs, but excludes the gas-breathing respiratory zone. The conduction zone also serves to offer a low resistance path for airflow. This provides a major defense role in its filtering capabilities.
Respiratory zones include respiratory bronchioles, alveolar ducts and alveoli, and are a site for the exchange of oxygen and carbon dioxide with blood. Respiratory bronchioles and alveolar ducts are responsible for 10% gas exchange. Alveoli is responsible for the other 90%. The respiratory zone represents the 16th through the division of 23 respiratory tracts.
From the bronchi, the dividing tube becomes smaller with about 20 to 23 divisions before ending in the alveolus.
Upper respiratory tract
The upper respiratory tract , may refer to parts of the respiratory system located above the sternal angle (beyond the thorax), above the vocal cords, or above the cricoid cartilage. The larynx is sometimes included in the upper and lower airways. The larynx is also called a voice box and has an associated cartilage that produces sound. These channels consist of nasal cavities and paranasal sinuses, pharynx (nasopharynx, oropharynx and laryngopharyngeal) and occasionally include the larynx.
Lower respiratory tract
The lower respiratory or lower airway ducts are from developed foregut and consist of trachea, bronchi (primary, secondary and tertiary), bronchioles (including terminals and respirations), and lungs (including alveoli). Sometimes it also includes the larynx.
The lower respiratory tract is also called the respiratory tree or tracheobronchial tree , to illustrate the airway branch structure that supplies air to the lungs, and includes trachea, bronchi and bronchioles.
- trachea
- main bronchus (diameter about 1 - 1.4 cm in adult)
- bronchus lobar (about 1 cm in diameter)
- segmental bronchus (diameter 4.5 to 13 mm)
- subsegmental bronchus (diameter 1 to 6 mm)
- do bronchiole
- terminal bronchiole
- bronchiole breathing
- alveolar channel
- alveolar sac
- alveolus
- alveolar sac
- alveolar channel
- bronchiole breathing
- terminal bronchiole
- do bronchiole
- subsegmental bronchus (diameter 1 to 6 mm)
- segmental bronchus (diameter 4.5 to 13 mm)
- bronchus lobar (about 1 cm in diameter)
- main bronchus (diameter about 1 - 1.4 cm in adult)
At any point of division or generation , one air channel becomes two or more smaller airways. The human respiratory tree can consist of an average of 23 generations, while the rat breathing tree has up to 13 generations. The proximal division (closest to the top of the tree, like the bronchus) primarily serves to transmit air into the lower airways. Then divisions include respiratory bronchiole, alveolar and alveoli channels, specifically for gas exchange.
The trachea is the largest tube in the respiratory tract and consists of a tracheal ring of hyaline cartilage. It branched into two bronchial tubes, the right and right bronchi. The bronchus branch enters the smaller part of the lung, called the bronchioles. This bronchioles cause air sacs in the lungs called alveoli.
lung is the largest organ in the lower respiratory tract. The lungs are suspended in the thoracic pleura cavity. The pleurae are two thin membranes, one thick layer of cells, which surround the lungs. The inside (visceral pleura) covers the lungs and the outer (parietal pleura) outlines the inner surface of the chest wall. This membrane secretes small amounts of fluid, allowing the lungs to move freely within the pleural space while expanding and contracting during breathing. The lungs are divided into different lobes. The right lung is larger than the left, because the heart is on the left of the midline. The right lung has three lobes - upper, middle, and lower (or superior, middle and inferior), and the left lung has two - upper and lower (or superior and inferior), plus a small tongue-shaped portion of the upper lobe known as the lingula. Each lobe is subdivided into a segment called the bronchopulmonary segment. Each lung has a rib surface, adjacent to the rib cage; the diaphragm surface, facing downward toward the diaphragm; and the mediastinal surface, which faces the center of the chest, and lies in the heart, vessels, and carinas where the two major bronchial branches are born from the base of the trachea.
The alveoli is a small air sac in the lungs where a gas exchange occurs. The average number of alveoli in human lungs is 480 million. When the diaphragm contracts, negative pressure is generated in the thorax and air rushes in to fill the cavity. When that happens, these pockets are filled with air, making the lungs expand. Alveoli are rich in capillaries, called capillary alveolors. Here red blood cells absorb oxygen from the air and then bring it back in the form of oxyhaemaglobin, to nourish the cells. The red blood cells also carry carbon dioxide (CO 2 ) away from the cell in the form of carboxyhemoglobin and release it to the alveoli through the alveolar capillaries. When the diaphragm is relaxed, positive pressure is generated in the thorax and air flows out of the alveoli that emit carbon dioxide.
Microanatomy
The respiratory tract is covered in the epithelium, which varies across the channel. There are glands and mucus produced by goblet cells in parts, as well as smooth muscle, elastin or cartilage. Much of the epithelium (from the nose to the bronchus) is enclosed in pseudostratified ciliated columnar epithelium, commonly called respiratory epithelium. Silia struck in one direction, moving mucus into the throat where he was swallowed. Moving down the bronchioles, the cells get more cuboid forms but are still ciliated.
Abundant glands in the upper respiratory tract, but there are fewer downs and they do not start in the bronchioles. The same is true for goblet cells, although there are scattered in the first bronchioles.
Cartilage is present to small bronchi. In their trachea is a C-shaped ring of hyaline cartilage, whereas in bronchial cartilage takes the form of an interspersed plate. The smooth muscle begins in the trachea, where it joins the C-shaped ring of cartilage. This keeps down the bronchi and bronchioles, which are completely surrounded. Instead of hard cartilage, the bronchi and bronchioles are composed of elastic tissue.
The lung consists of thirteen types of cells, eleven types of epithelial cells and two types of mesenchymal cells. Epithelial cells form a layer of trachea, and bronchial tubes, while mesenchymal cells lining the lungs.
Maps Respiratory tract
Function
Most respiratory tracts exist only as airborne piping systems to travel in the lungs, and the alveoli is the only part of the lung that exchanges oxygen and carbon dioxide with blood.
Respirasi
Respiration is a rhythmic process of breathing, in which air is drawn into the lung alveoli through inhalation and then released by breathing. When a person breathes air, air travels down the trachea, through the bronchial tubes, and into the lungs. The entire channel is protected by ribs, spine, and sternum. In the lungs, the oxygen from the inhaled air is transferred into the blood and circulated throughout the body. Carbon dioxide (CO 2 ) is transferred from returning the blood back to the gas form in the lungs and exhaled through the lower respiratory tract and then the upper part, to complete the respiratory process.
Unlike trachea and bronchi, the upper air ducts are collapsible and folded tubes. Thus, it must be able to withstand the suction pressure generated by the rhythmic contraction of the diaphragm that sucks air into the lungs. This is achieved by rhythmic contractions of the upper airway muscles, such as the genioglossus (tongue) and hyoid muscles. In addition to the rhythmic innervation of the respiratory center in the medulla oblongata, motor neurons that control muscles also receive tonic innervation that establishes the level of stiffness and basic size.
The diaphragm is the major muscle that allows for the expansion and contraction of the lungs. Smaller muscles between the ribs, external intercostals, help this process.
Defense against infection
The upper respiratory epithelial lining is interspersed with goblet cells that secrete protective mucus. It helps filter out the waste, which is eventually ingested into a highly acidic stomach environment or is ejected through a spit. The epithelium lining the respiratory tract is covered by tiny hairs called cilia. It puls rhythmically out of the lungs, removing mucus particles secreted toward the laryngopharynx up and out, in a process called the mucociliary escalator. In addition to keeping the lower sterile respiratory passages, they prevent the accumulation of mucus in the lungs. Macrophages in the alveoli are part of the immune system that swallows and digests the inhaled dangerous agent.
The hair in the nostrils plays a protective role, trapping particles like dust. The cough reflex expels all irritation inside the mucous membrane to the outside. Lung airways contain muscle rings. When the alleys are disrupted by some allergens, these muscles can narrow.
Clinical interests
Respiratory tract is a common place for infection.
Infection
Upper respiratory tract infection is probably the most common infection in the world.
The respiratory system is particularly vulnerable to developing infections in the lungs. Older babies and adults are more likely to develop infections in their lungs, because their lungs are not strong in fighting this infection. Most of these infections used to be fatal, but with new research and drugs, they can now be treated. With bacterial infections, antibiotics are prescribed, while viral infections are more difficult to treat, but can still be cured.
Common flu/flu is the most common cause for upper respiratory tract infections, which can lead to more serious diseases that can develop in the lower respiratory tract. Pneumonia is the most common and frequent underlying respiratory tract infection. This can be viruses, bacteria, or fungi. This infection is very common, because pneumonia can be in the air, and when you inhale this infection in the air, the particles enter the lungs and move into the air sacs. This infection quickly develops in the lower part of the lungs, and fills the lungs with fluid, and excess mucus. This causes difficulty in breathing, and coughs when the lower respiratory tract tries to get rid of fluid in the lungs. You can be more vulnerable to developing this infection if you have asthma, flu, heart disease, or cancer
Bronchitis is another common infection that occurs in the lower respiratory tract. This is an inflammation of the bronchial tubes. There are two forms of this infection: acute bronchitis, which can be treated and can be lost without treatment, or chronic bronchitis, coming and going, but it will always affect a person's lungs. Bronchitis increases the amount of natural mucus in your respiratory tract. Chronic bronchitis often occurs in smokers, because tar from cigarettes accumulates over time, causing the lungs to work harder to repair themselves.
Tuberculosis is one of many other infections that occur in the lower respiratory tract. You can contract this infection from droplets in the air, and if inhaled, you are at risk of developing the disease. It is a bacterial infection that worsens the lung tissue resulting in coughing up blood. This infection is lethal if left untreated.
Lung cancer
Some of these cancers have environmental causes such as smoking. When tobacco products are inhaled, smoke paralyzes cilia, causing mucus to enter the lungs. Frequent smoking, over time causes cilia's hair to die and can no longer filter out mucus. Tar from the smoke inhaled into the lungs, turning the black lung into black. This tar accumulation may eventually lead to lung cancer, or chronic obstructive pulmonary disease.
Chronic obstructive pulmonary disease
Chronic obstructive pulmonary disease (COPD) is a common underlying respiratory disease that can be caused by exposure to hazardous chemicals, or prolonged use of tobacco. The disease is chronic and progressive, the damage to the lungs can not be changed and ultimately fatal. COPD destroys the alveoli, and lung tissue that makes breathing very difficult, causing shortness of breath, hyperventilation, and lifting the chest. Decreased alveoli leads to loss of oxygen supply to the lungs, and an increase in carbon dioxide accumulation. There are two types of COPD: primary and secondary. Primary COPD can be found in young adults. This type of COPD worsens the air sacs, and the lung mass. Secondary COPD can be found in older adults who smoke or smoke and have a history of bronchitis. The old terms for COPD are emphysema and chronic bronchitis .
Asthma
The bronchus is the main channel to the right and left lung. This airway carries oxygen to the bronchioles in the lungs. Inflammation of the bronchi and bronchioles may cause them to swell, which can lead to asthma attacks. This causes shortness of breath, chest tightness and difficulty breathing. There are different types of asthma that affect the function of the bronchial tubes. Allergies can also trigger allergic reactions, causing swelling of the bronchial tubes; as a result, the airways will swell, or close completely.
See also
- Jet vents
- Nasopharyngeal breathing line
- Oropharyngeal respiratory tract
References
Source of the article : Wikipedia
0 Comments