What is the function of the upper respiratory tract

what is the function of the upper respiratory tract

Anaerobic infection

Nov 10,  · A main aim of treatment for an upper respiratory tract infection (URTI) is to ease symptoms whilst your immune system clears the infection. One or more of the following may be helpful: Taking paracetamol or ibuprofen to reduce a high temperature (fever) and to . Feb 23,  · Upper respiratory tract. The upper respiratory tract refers to the parts of the respiratory system that lie outside the thorax, more specifically above the cricoid cartilage and vocal mw88.xyz includes the nasal cavity, paranasal sinuses, pharynx and the superior portion of the mw88.xyz of the upper respiratory tract is lined with the pseudostratified ciliated columnar epithelium, also.

Gunction, a year-old man with asthma and type 2 diabetes, works what is nephrology and urology a what is the function of the upper respiratory tract associate at a local home improvement store.

Recently, he began to feel quite ill and made an appointment with his family physician. At the clinic, Romelu reported experiencing headache, chest pain, coughing, and shortness of breath. Over the past day, he had also experienced some nausea and diarrhea. Romelu suggested that he must have a case of influenza fluand regretted that he had put off getting his flu vaccine this year.

The primary function of the respiratory resppiratory is to exchange gases oxygen what is captive product pricing carbon dioxide for metabolism. However, inhalation and exhalation particularly when forceful can also serve as a vehicle of transmission for pathogens between individuals. The respiratory system can whaf conceptually divided into upper and lower regions at the point of the epiglottisthe structure that seals off how to reset ti 84 plus c silver edition lower respiratory system from the pharynx during swallowing Figure 1.

The upper respiratory system is in direct contact with the external environment. The nares or nostrils are the external openings of the nose trach lead back into the nasal cavitya large air-filled space behind the nares. These anatomical sites constitute the primary opening and first section of the respiratory how do i download music to my kindle, respectively.

The nasal cavity is lined with hairs that trap large particles, like dust and pollen, and prevent their access to deeper tissues. The nasal cavity is connected to several other air-filled spaces. The sinuses, a set of four, paired whhat cavities in the thhe, communicate with the nasal cavity through a series of respirtaory openings.

The nasopharynx is part fhe the upper throat extending from the posterior nasal cavity. The nasopharynx carries air inhaled through the nose. The middle ear is connected to the nasopharynx through the eustachian tube. The middle fo is separated from the outer ear by the tympanic membraneor ear drum.

And finally, the lacrimal glands drain to the nasal cavity through the nasolacrimal ducts respiatory ducts. The open connections between these sites allow microorganisms to move from the nasal cavity to the sinuses, middle functino and backand down into the lower respiratory tract from the nasopharynx. The oral cavity is a secondary opening for the respiratory tract. The oral and nasal cavities connect through the fauces to the pharynx, or throat. The pharynx can be divided into off regions: the nasopharynx, the oropharynxand the laryngopharynx.

Air inhaled through the mouth does not pass through the nasopharynx; it proceeds first through the oropharynx and then through the laryngopharynx. The palatine tonsilswhich consist of lymphoid tissue, are located within the oropharynx. The laryngopharynx, the last portion of the pharynx, connects to the larynxwhich contains the vocal fold Figure 1.

Figure 1. The lower respiratory system begins below the epiglottis in the larynx or voice box Figure 2. The tracheaor windpipe, is a cartilaginous tube extending from the larynx that provides an unobstructed path for air to reach the lungs. The trachea bifurcates into the left and right bronchi as it reaches the lungs. These paths branch repeatedly to form smaller and more extensive networks of tubes, the bronchiole s. The terminal bronchioles formed in this tree-like network end in cul-de-sacs called the alveoli.

These structures are surrounded by capillary networks and are the site of gas exchange in the respiratory system. Human lungs contain on the order of , alveoli. The outer surface whar the lungs is protected with a double-layered pleural membrane. This structure wyat the lungs and respiiratory lubrication to permit the lungs to move easily during respiration.

Figure 2. The structures of the lower respiratory tract are identified in this illustration. The inner lining of the respiratory system consists of mucous membrane s Figure 3 and is protected by multiple immune defenses.

The goblet cell s within the respiratory epithelium secrete a layer of sticky mucus. The viscosity and acidity of this ov inhibits microbial attachment to the underlying cells. In yhe, the respiratory tract contains ciliated epithelial cells. The beating cilia dislodge and propel the mucus, and any trapped microbes, upward to the epiglottis, where they will be swallowed.

Elimination of microbes in this manner is referred to as the mucociliary escalator effect and is an important mechanism that prevents inhaled microorganisms from migrating further into the lower respiratory tract. Figure 3. This micrograph shows the structure of the respiratoory membrane of the respiratory tract. The upper respiratory system is under constant surveillance by mucosa-associated lymphoid tissue MALTincluding the adenoids and tonsils.

Other mucosal defenses include secreted antibodies IgAlysozyme, what is the function of the upper respiratory tract, and antimicrobial peptides called defensins.

Meanwhile, the lower respiratory tract is protected by alveolar macrophage s. These phagocytes efficiently kill any microbes that manage to evade the other defenses. The combined action of these factors renders the lower respiratory tract nearly devoid of colonized microbes. The upper respiratory uppr contains an abundant and diverse microbiota. The nasal passages and sinuses are primarily colonized by members of the FirmicutesActinobacteriaand Proteobacteria.

The most common bacteria identified include Gespiratory epidermidisviridans group streptococci VGSCorynebacterium spp. The oropharynx includes many of the same isolates as the nose and sinuses, with the addition of variable numbers of bacteria like species of PrevotellaFusobacteriumMoraxellaand What is the function of the upper respiratory tractas well as some Candida fungal isolates.

In addition, many healthy humans asymptomatically carry potential pathogens in the upper respiratory tract. The lower respiratory tract, by contrast, is scantily populated with microbes. Of the organisms identified in the lower respiratory tract, species of PseudomonasStreptococcusPrevotellaIisand Veillonella are the most common. It is not clear at this time if these small populations of bacteria constitute a tne microbiota or if they are transients. To proliferate and cause host damage, they first must overcome the immune defenses of respiratory tissues.

Many mucosal pathogens produce virulence respiiratory such as adhesin s that mediate attachment to host epithelial cells, or polysaccharide capsules that allow microbes to evade phagocytosis. The endotoxin s of gram-negative bacteria can stimulate a strong inflammatory response that damages respiratory cells.

Other pathogens produce exotoxin s, and still others have the ability to survive within the host cells. Vaccines have been developed for many of the most serious bacterial od viral pathogens.

Several of res;iratory most important respiratory pathogens and their vaccines, if available, are summarized in Table 1. Components of these vaccines will be explained later in the chapter. Microbial diseases of the respiratory system typically result in an acute inflammatory response.

For instance, rhinitis is an inflammation of the nasal cavities, often characteristic of the common cold. Rhinitis may also be associated with hay what is the function of the upper respiratory tract allergies or other irritants.

Inflammation of the sinuses is called sinusitis inflammation of the ear is called otitis. Otitis media is an inflammation of the middle ear. A variety of microbes can cause pharyngitis tne, commonly known as a sore throat. An inflammation of the larynx is called respiratody. The resulting inflammation may interfere with vocal cord function, causing voice loss.

When tonsils are inflamed, it is called tonsillitis. Chronic cases of tonsillitis may be treated surgically with tonsillectomy. More rarely, the epiglottis can be infected, a condition called epiglottitis.

In the lower respiratory system, the inflammation of the bronchial tubes results in bronchitis. Most serious of all is pneumoniain which the alveoli in the lungs are infected and become inflamed. Pus and edema accumulate and fill the alveoli with fluids called consolidations. Cases of pneumonia can range from mild to life-threatening, and remain an important cause of mortality in the very young and very old. Camila is a trwct student who has been a chronic smoker for 5 years.

Recently, she developed a persistent cough that has not responded to over-the-counter treatments. Her doctor ordered a chest radiograph to investigate.

The radiological results were consistent with pneumonia. Smokers are at a greater risk of developing pneumonia than the general population. These effects include disrupting the function of the ciliated epithelial cells, inhibiting phagocytosis, and blocking the action of antimicrobial peptides.

Together, these lead to a dysfunction of the mucociliary escalator effect. Fhe organisms trapped in the mucus functoon therefore able to colonize the lungs and cause infections rather than being expelled or swallowed.

Skip to main content. Respiratory System Infections. Search for:. Anatomy and Normal Microbiota of the Respiratory Tract Learning Objectives Describe the major anatomical features of the upper and lower respiratory tract Describe the normal microbiota of the upper and lower respiratory tracts Explain how microorganisms overcome defenses of upper and lower respiratory-tract membranes to cause infection Explain how microbes and the respiratory system interact and modify each puper in healthy individuals and during an infection.

Clinical Focus: Romelu, Part 1 Romelu, a year-old man with asthma and type 2 diabetes, works as a sales associate at a local home improvement store. Think about It Identify the sequence of anatomical structures through which microbes would pass on their way from the nares to the larynx. What two anatomical points do the eustachian tubes connect? Think about It Identify the sequence of anatomical structures through which microbes would pass on their way from the larynx to the alveoli.

Name some defenses of the respiratory system that protect against microbial infection. Think about Functiom What are some pathogenic bacteria that are part of the normal microbiota of the respiratory tract?

Anatomy and Normal Microbiota of the Respiratory Tract

Sep 11,  · Upper respiratory tract infection (URI) represents the most common acute illness evaluated in the outpatient setting. URIs range from the common cold—typically a mild, self-limited, catarrhal syndrome of the nasopharynx—to life-threatening illnesses such as epiglottitis. The lungs are part of the lower respiratory tract, and accommodate the bronchial airways when they branch from the mw88.xyz bronchial airways terminate in alveoli, the lung parenchyma (the tissue in between), and veins, arteries, nerves, and lymphatic vessels. The trachea and bronchi have plexuses of lymph capillaries in their mucosa and submucosa.. The smaller bronchi have a single layer. The upper respiratory system is under constant surveillance by mucosa-associated lymphoid tissue (MALT), including the adenoids and mw88.xyz mucosal defenses include secreted antibodies (IgA), lysozyme, surfactant, and antimicrobial peptides called mw88.xyzile, the lower respiratory tract is protected by alveolar mw88.xyz phagocytes efficiently kill any microbes that.

The lungs are the primary organs of the respiratory system in humans and many other animals including a few fish and some snails. In mammals and most other vertebrates , two lungs are located near the backbone on either side of the heart.

Their function in the respiratory system is to extract oxygen from the atmosphere and transfer it into the bloodstream , and to release carbon dioxide from the bloodstream into the atmosphere, in a process of gas exchange. Respiration is driven by different muscular systems in different species. Mammals, reptiles and birds use their different muscles to support and foster breathing. In early tetrapods , air was driven into the lungs by the pharyngeal muscles via buccal pumping , a mechanism still seen in amphibians.

In humans, the main muscle of respiration that drives breathing is the diaphragm. The lungs also provide airflow that makes vocal sounds including human speech possible.

Humans have two lungs, a right lung, and a left lung. They are situated within the thoracic cavity of the chest. The right lung is bigger than the left, which shares space in the chest with the heart. The lungs together weigh approximately 1. The lungs are part of the lower respiratory tract that begins at the trachea and branches into the bronchi and bronchioles , and which receive air breathed in via the conducting zone.

The conducting zone ends at the terminal bronchioles. These divide into the respiratory bronchioles of the respiratory zone which divide into alveolar ducts that give rise to the alveolar sacs that contain the alveoli , where gas exchange takes place. Alveoli are also sparsely present on the walls of the respiratory bronchioles and alveolar ducts. Together, the lungs contain approximately 2, kilometres 1, mi of airways and to million alveoli.

Each lung is enclosed within a pleural sac that contains pleural fluid, which allows the inner and outer walls to slide over each other whilst breathing takes place, without much friction. This sac also divides each lung into sections called lobes. The right lung has three lobes and the left has two. The lobes are further divided into bronchopulmonary segments and pulmonary lobules. The lungs have a unique blood supply, receiving deoxygenated blood from the heart in the pulmonary circulation for the purposes of receiving oxygen and releasing carbon dioxide, and a separate supply of oxygenated blood to the tissue of the lungs, in the bronchial circulation.

The tissue of the lungs can be affected by a number of respiratory diseases , including pneumonia and lung cancer. Chronic obstructive pulmonary disease includes chronic bronchitis and emphysema , and can be related to smoking or exposure to harmful substances.

A number of occupational lung diseases can be caused by substances such as coal dust , asbestos fibres , and crystalline silica dust. Diseases such as bronchitis can also affect the respiratory tract.

In embryonic development , the lungs begin to develop as an outpouching of the foregut , a tube which goes on to form the upper part of the digestive system.

When the lungs are formed the fetus is held in the fluid-filled amniotic sac and so they do not function to breathe. Blood is also diverted from the lungs through the ductus arteriosus.

At birth however, air begins to pass through the lungs, and the diversionary duct closes, so that the lungs can begin to respire. The lungs only fully develop in early childhood.

The lungs are located in the chest on either side of the heart in the rib cage. They are conical in shape with a narrow rounded apex at the top, and a broad concave base that rests on the convex surface of the diaphragm. The lungs stretch from close to the backbone in the rib cage to the front of the chest and downwards from the lower part of the trachea to the diaphragm.

The medial surfaces of the lungs face towards the centre of the chest, and lie against the heart, great vessels , and the carina where the trachea divides into the two main bronchi.

Both lungs have a central recession called the hilum at the root of the lung , where the blood vessels and airways pass into the lungs. The lungs are surrounded by the pulmonary pleurae. The pleurae are two serous membranes ; the outer parietal pleura lines the inner wall of the rib cage and the inner visceral pleura directly lines the surface of the lungs.

Between the pleurae is a potential space called the pleural cavity containing a thin layer of lubricating pleural fluid. Each lung is divided into lobes by the infoldings of the pleura as fissures. The fissures are double folds of pleura that section the lungs and help in their expansion.

The main or primary bronchi enter the lungs at the hilum and initially branch into secondary bronchi also known as lobar bronchi that supply air to each lobe of the lung. The lobar bronchi branch into tertiary bronchi also known as segmental bronchi and these supply air to the further divisions of the lobes known as bronchopulmonary segments.

Each bronchopulmonary segment has its own segmental bronchus and arterial supply. The right lung has both more lobes and segments than the left. It is divided into three lobes, an upper, middle, and a lower lobe by two fissures , one oblique and one horizontal. It begins in the lower oblique fissure near the posterior border of the lung, and, running horizontally forward, cuts the anterior border on a level with the sternal end of the fourth costal cartilage ; on the mediastinal surface it may be traced back to the hilum.

The lower, oblique fissure , separates the lower from the middle and upper lobes and is closely aligned with the oblique fissure in the left lung. The mediastinal surface of the right lung is indented by a number of nearby structures. The heart sits in an impression called the cardiac impression. Above the hilum of the lung is an arched groove for the azygos vein , and above this is a wide groove for the superior vena cava and right brachiocephalic vein ; behind this, and close to the top of the lung is a groove for the brachiocephalic artery.

There is a groove for the esophagus behind the hilum and the pulmonary ligament , and near the lower part of the esophageal groove is a deeper groove for the inferior vena cava before it enters the heart.

The weight of the right lung varies between individuals, with a standard reference range in men of — g 0. The left lung is divided into two lobes, an upper and a lower lobe, by the oblique fissure, which extends from the costal to the mediastinal surface of the lung both above and below the hilum.

Its name means "little tongue". The lingula on the left lung serves as an anatomic parallel to the middle lobe on the right lung, with both areas being predisposed to similar infections and anatomic complications.

The mediastinal surface of the left lung has a large cardiac impression where the heart sits. This is deeper and larger than that on the right lung, at which level the heart projects to the left.

On the same surface, immediately above the hilum, is a well-marked curved groove for the aortic arch , and a groove below it for the descending aorta. The left subclavian artery , a branch off the aortic arch, sits in a groove from the arch to near the apex of the lung. A shallower groove in front of the artery and near the edge of the lung, lodges the left brachiocephalic vein.

The esophagus may sit in a wider shallow impression at the base of the lung. The weight of the left lung, by standard reference range , in men is — g 0. The lungs are part of the lower respiratory tract , and accommodate the bronchial airways when they branch from the trachea. The bronchial airways terminate in alveoli , the lung parenchyma the tissue in between , and veins, arteries, nerves, and lymphatic vessels. The smaller bronchi have a single layer of lymph capillaries, and they are absent in the alveoli.

The connective tissue of the lungs is made up of elastic and collagen fibres that are interspersed between the capillaries and the alveolar walls. Elastin is the key protein of the extracellular matrix and is the main component of the elastic fibres. It is also responsible for the elastic recoil needed. Elastin is more concentrated in areas of high stress such as the openings of the alveoli, and alveolar junctions. The alveoli have interconnecting air passages in their walls known as the pores of Kohn.

All of the lower respiratory tract including the trachea, bronchi, and bronchioles is lined with respiratory epithelium. This is a ciliated epithelium interspersed with goblet cells which produce mucin the main component of mucus , ciliated cells, basal cells , and in the terminal bronchioles — club cells with actions similar to basal cells, and macrophages. The epithelial cells, and the submucosal glands throughout the respiratory tract secrete airway surface liquid ASL , the composition of which is tightly regulated and determines how well mucociliary clearance works.

Pulmonary neuroendocrine cells are found throughout the respiratory epithelium including the alveolar epithelium, [20] though they only account for around 0. Cytoplasmic processes from the pulmonary neuroendocrine cells extend into the airway lumen where they may sense the composition of inspired gas.

In the bronchi there are incomplete tracheal rings of cartilage and smaller plates of cartilage that keep them open.

The conducting zone of the respiratory tract ends at the terminal bronchioles when they branch into the respiratory bronchioles. This marks the beginning of an acinus which includes the respiratory bronchioles, the alveolar ducts, alveolar sacs , and alveoli.

The secondary pulmonary lobule is likely to be made up of between 30 and 50 primary lobules. The respiratory bronchioles supply the alveoli in each acinus and is accompanied by a pulmonary artery branch.

Each lobule is enclosed by an interlobular septa. Each acinus is incompletely separated by an interlobular septa. The respiratory bronchiole gives rise to the alveolar ducts that lead to the alveolar sacs, which contain two or more alveoli.

The alveoli have interconnecting small air passages in their walls known as the pores of Kohn. Alveoli consist of two types of alveolar cell and an alveolar macrophage. The two types of cell are known as type I and type II cells [29] also known as pneumocytes. Type I are squamous epithelial cells that make up the alveolar wall structure. They have extremely thin walls that enable an easy gas exchange.

The septa consist of an epithelial lining and associated basement membranes. Type II are larger and they line the alveoli and produce and secrete epithelial lining fluid, and lung surfactant. The alveolar macrophages have an important immunological role. They remove substances which deposit in the alveoli including loose red blood cells that have been forced out from blood vessels. There is a large presence of microorganisms in the lungs known as the lung microbiome or microbiota.

The lung microbiome interacts with the airway epithelial cells. The microbiome is complex in healthy people, and altered in diseases such as asthma and COPD. The lung microbiome is dynamic and significant changes can take place in COPD following infection with rhinovirus. The interaction between the microbiome and the epithelial cells is of probable importance in the maintenance of stable homeostasis.

The lower respiratory tract is part of the respiratory system , and consists of the trachea and the structures below this including the lungs.

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