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55-415: Green Cross may refer to: Science [ edit ] Green Cross (chemical warfare) , a group of World War I chemical warfare agents Businesses [ edit ] Green Cross (South Korea) , a South Korean pharmaceutical company Green Cross (Japan) , a Japanese pharmaceutical company Health and safety [ edit ] Green Cross Code ,

110-693: A Venezuelan paramedic group Cannabis dispensary , indicated sometimes by a green cross sign Pharmacy , indicated in some countries by a green cross sign Sports [ edit ] C.A. Green Cross , an Ecuadorian football (soccer) club Club de Deportes Green Cross (1916–1985), a former Chilean football (soccer) club See also [ edit ] All pages with titles containing Green Cross Blue Cross (disambiguation) Bronze Cross (disambiguation) Gold Cross (disambiguation) Red Cross (disambiguation) Silver Cross (disambiguation) White Cross (disambiguation) Yellow cross (disambiguation) Topics referred to by

165-417: 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 . The left lung, unlike the right, does not have a middle lobe, though it does have a homologous feature, a projection of the upper lobe termed the lingula . Its name means "little tongue". The lingula on the left lung serves as an anatomic parallel to the middle lobe on

220-485: A right lung with only two lobes, or a left lung with three lobes. A variation in the airway branching structure has been found specifically in the central airway branching. This variation is associated with the development of COPD in adulthood. The development of the human lungs arise from the laryngotracheal groove and develop to maturity over several weeks in the foetus and for several years following birth. The larynx , trachea , bronchi and lungs that make up

275-755: A traffic safety education program in the United Kingdom Green Cross Corps , an alternative name for the British Women's Reserve Ambulance Corps Green Cross flags , the industrial safety/health flags in Japan Green Cross for Safety Award from the National Safety Council Green Cross International , an environmental organization founded by Mikhail Gorbachev Green Cross (Venezuela)  [ es ] ,

330-414: 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 connective tissue links all the alveoli to form the lung parenchyma which has a sponge-like appearance. The alveoli have interconnecting air passages in their walls known as the pores of Kohn . All of the lower respiratory tract including

385-460: Is bigger than the left, the left lung shares space in the chest with the heart. The lungs together weigh approximately 1.3 kilograms (2.9 lb), and the right is heavier. 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 . These divide until air reaches microscopic alveoli , where gas exchange takes place. Together,

440-500: Is different from Wikidata All article disambiguation pages All disambiguation pages Green Cross (chemical warfare) Green Cross is also a generic World War I German marking for artillery shells with pulmonary agents (chemical payload affecting the lungs ). The tip of the projectile with the fuse end painted green and a green cross at the bottom of the cartridge. Other Green Cross mixtures were based on phosgene and/or diphosgene . The first use of Green Cross

495-422: Is divided into three lobes by a horizontal fissure , and an oblique fissure . The left lung is divided into two lobes by an oblique fissure which is closely aligned with the oblique fissure in the right lung. In the right lung the upper horizontal fissure, separates the upper (superior) lobe from the middle lobe. The lower, oblique fissure separates the lower lobe from the middle and upper lobes. Variations in

550-401: 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. In humans the lungs are located in the chest on either side of

605-427: Is likely to be made up of between 30 and 50 primary lobules. The lobule is supplied by a terminal bronchiole that branches into respiratory bronchioles. The respiratory bronchioles supply the alveoli in each acinus and is accompanied by a pulmonary artery branch. Each lobule is enclosed by an interlobular septum. Each acinus is incompletely separated by an intralobular septum. The respiratory bronchiole gives rise to

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660-435: Is the part of the lung distal to the respiratory bronchiole. Thus, it includes the alveolar ducts, sacs, and alveoli but not the respiratory bronchioles. The unit described as the secondary pulmonary lobule is the lobule most referred to as the pulmonary lobule or respiratory lobule . This lobule is a discrete unit that is the smallest component of the lung that can be seen without aid. The secondary pulmonary lobule

715-425: The carina where the trachea divides into the two main bronchi. The cardiac impression is an indentation formed on the surfaces of the lungs where they rest against the heart. Both lungs have a central recession called the hilum , where the blood vessels and airways pass into the lungs making up the root of the lung . There are also bronchopulmonary lymph nodes on the hilum. The lungs are surrounded by

770-470: The circulation , and carbon dioxide diffuses from the blood into the lungs to be breathed out . Estimates of the total surface area of lungs vary from 50 to 75 square metres (540 to 810 sq ft); although this is often quoted in textbooks and the media being "the size of a tennis court", it is actually less than half the size of a singles court . The bronchi in the conducting zone are reinforced with hyaline cartilage in order to hold open

825-438: 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 155–720 g (0.342–1.587 lb) and in women of 100–590 g (0.22–1.30 lb). The left lung is divided into two lobes, an upper and

880-418: 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 apex of the lung extends into the root of the neck, reaching shortly above the level of the sternal end of the first rib . The lungs stretch from close to the backbone in the rib cage to the front of the chest and downwards from

935-429: 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 musculoskeletal systems to support and foster breathing. In early tetrapods, air

990-676: The immune system . 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 microbiota that interacts with the airway epithelial cells; an interaction of probable importance in maintaining homeostasis. The microbiota is complex and dynamic in healthy people, and altered in diseases such as asthma and COPD . For example significant changes can take place in COPD following infection with rhinovirus . Fungal genera that are commonly found as mycobiota in

1045-427: 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 . Middle Lower Lingula Lower Each lung is divided into sections called lobes by

1100-473: The airways initiate a reflex known as the Hering–Breuer reflex that prevents the lungs from over-inflation, during forceful inspiration. The lungs have a dual blood supply provided by a bronchial and a pulmonary circulation . The bronchial circulation supplies oxygenated blood to the airways of the lungs, through the bronchial arteries that leave the aorta . There are usually three arteries, two to

1155-399: The airways. The bronchioles have no cartilage and are surrounded instead by smooth muscle . Air is warmed to 37 °C (99 °F), humidified and cleansed by the conducting zone. Particles from the air being removed by the cilia on the respiratory epithelium lining the passageways, in a process called mucociliary clearance . Pulmonary stretch receptors in the smooth muscle of

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1210-464: The alveolar ducts that lead to the alveolar sacs, which contain two or more alveoli. The walls of the alveoli are extremely thin allowing a fast rate of diffusion . 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 (also known as pneumocytes). Types I and II make up

1265-474: The alveolar septa which separate each alveolus. The septa consist of an epithelial lining and associated basement membranes . Type I cells are not able to divide, and consequently rely on differentiation from Type II cells. Type II are larger and they line the alveoli and produce and secrete epithelial lining fluid, and lung surfactant . Type II cells are able to divide and differentiate to Type I cells. The alveolar macrophages have an important role in

1320-462: The alveoli. The four genes mostly associated with branching morphogenesis in the lung are the intercellular signalling protein – sonic hedgehog (SHH), fibroblast growth factors FGF10 and FGFR2b, and bone morphogenetic protein BMP4 . FGF10 is seen to have the most prominent role. FGF10 is a paracrine signalling molecule needed for epithelial branching, and SHH inhibits FGF10. The development of

1375-410: The base of the lung. By standard reference range , the weight of the left lung is 110–675 g (0.243–1.488 lb) in men and 105–515 g (0.231–1.135 lb) in women. 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 which make up the functional tissue ( parenchyma ) of

1430-416: The branch. In the development of the lungs (as in some other organs) the epithelium forms branching tubes. The lung has a left-right symmetry and each bud known as a bronchial bud grows out as a tubular epithelium that becomes a bronchus. Each bronchus branches into bronchioles. The branching is a result of the tip of each tube bifurcating. The branching process forms the bronchi, bronchioles, and ultimately

1485-402: The bronchus and bronchioles, and increases the secretions from glands. The lungs also have a sympathetic tone from norepinephrine acting on the beta 2 adrenoceptors in the respiratory tract, which causes bronchodilation . The action of breathing takes place because of nerve signals sent by the respiratory center in the brainstem , along the phrenic nerve from the cervical plexus to

1540-533: 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, though they only account for around 0.5 percent of the total epithelial population. PNECs are innervated airway epithelial cells that are particularly focused at airway junction points. These cells can produce serotonin, dopamine, and norepinephrine, as well as polypeptide products. Cytoplasmic processes from

1595-423: The diaphragm. The lobes of the lung are subject to anatomical variations . A horizontal interlobar fissure was found to be incomplete in 25% of right lungs, or even absent in 11% of all cases. An accessory fissure was also found in 14% and 22% of left and right lungs, respectively. An oblique fissure was found to be incomplete in 21% to 47% of left lungs. In some cases a fissure is absent, or extra, resulting in

1650-460: The fissures are fairly common being either incompletely formed or present as an extra fissure as in the azygos fissure , or absent. Incomplete fissures are responsible for interlobar collateral ventilation , airflow between lobes which is unwanted in some lung volume reduction procedures. 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

1705-406: 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

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1760-413: The infoldings of the visceral pleura as fissures. Lobes are divided into segments, and segments have further divisions as lobules. There are three lobes in the right lung and two lobes in the left lung. The fissures are formed in early prenatal development by invaginations of the visceral pleura that divide the lobar bronchi, and section the lungs into lobes that helps in their expansion. The right lung

1815-628: The left has two. The lobes are further divided into bronchopulmonary segments and lobules. The lungs have a unique blood supply, receiving deoxygenated blood sent from the heart for the purposes of receiving oxygen (the pulmonary circulation ) and a separate supply of oxygenated blood (the bronchial circulation ). The tissue of the lungs can be affected by a number of respiratory diseases , including pneumonia and lung cancer . Chronic diseases such as chronic obstructive pulmonary disease and emphysema can be related to smoking or exposure to harmful substances. Diseases such as bronchitis can also affect

1870-458: The left lung and one to the right, and they branch alongside the bronchi and bronchioles. The pulmonary circulation carries deoxygenated blood from the heart to the lungs and returns the oxygenated blood to the heart to supply the rest of the body. The blood volume of the lungs is about 450 millilitres on average, about 9% of the total blood volume of the entire circulatory system. This quantity can easily fluctuate from between one-half and twice

1925-420: The lower part of the trachea to the diaphragm. The left lung shares space with the heart, and has an indentation in its border called the cardiac notch of the left lung to accommodate this. The front and outer sides of the lungs face the ribs, which make light indentations on their surfaces. The medial surfaces of the lungs face towards the centre of the chest, and lie against the heart, great vessels , and

1980-495: The lung, 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 of lymph capillaries, and they are absent in the alveoli. The lungs are supplied with the largest lymphatic drainage system of any other organ in the body. Each lung is surrounded by a serous membrane of visceral pleura , which has an underlying layer of loose connective tissue attached to

2035-415: 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 . Segments for the left and right lung are shown in the table. The segmental anatomy is useful clinically for localising disease processes in

2090-404: The lungs contain approximately 2,400 kilometres (1,500 mi) of airways and 300 to 500 million alveoli. Each lung is enclosed within a pleural sac of two pleurae which allows the inner and outer walls to slide over each other whilst breathing takes place, without much friction. The inner visceral pleura divides each lung as fissures into sections called lobes. The right lung has three lobes and

2145-419: The lungs. A segment is a discrete unit that can be surgically removed without seriously affecting surrounding tissue. 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. The upper, horizontal fissure, separates the upper from the middle lobe. It begins in the lower oblique fissure near

2200-409: The microbiota include Candida , Malassezia , Saccharomyces , and Aspergillus . The lower respiratory tract is part of the respiratory system , and consists of the trachea and the structures below this including the lungs. The trachea receives air from the pharynx and travels down to a place where it splits (the carina ) into a right and left primary bronchus . These supply air to

2255-416: The normal volume. Also, in the event of blood loss through hemorrhage, blood from the lungs can partially compensate by automatically transferring to the systemic circulation. The lungs are supplied by nerves of the autonomic nervous system . Input from the parasympathetic nervous system occurs via the vagus nerve . When stimulated by acetylcholine , this causes constriction of the smooth muscle lining

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2310-406: 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

2365-467: 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. Bronchioles are too narrow to support cartilage and their walls are of smooth muscle , and this is largely absent in the narrower respiratory bronchioles which are mainly just of epithelium. The absence of cartilage in

2420-404: The respiratory tract, begin to form during the fourth week of embryogenesis from the lung bud which appears ventrally to the caudal portion of the foregut . The respiratory tract has a branching structure, and is also known as the respiratory tree. In the embryo this structure is developed in the process of branching morphogenesis , and is generated by the repeated splitting of the tip of

2475-456: The respiratory tract. Medical terms related to the lung often begin with pulmo-, from the Latin pulmonarius (of the lungs) as in pulmonology, or with pneumo- (from Greek πνεύμων "lung") as in pneumonia. 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

2530-429: The right and left lungs, splitting progressively into the secondary and tertiary bronchi for the lobes of the lungs, and into smaller and smaller bronchioles until they become the respiratory bronchioles . These in turn supply air through alveolar ducts into the alveoli , where the exchange of gases take place. Oxygen breathed in , diffuses through the walls of the alveoli into the enveloping capillaries and into

2585-403: 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

2640-425: The right lung, with both areas being predisposed to similar infections and anatomic complications. There are two bronchopulmonary segments of the lingula: superior and inferior. 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

2695-419: The same term [REDACTED] This disambiguation page lists articles associated with the title Green Cross . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Green_Cross&oldid=1213898090 " Category : Disambiguation pages Hidden categories: Short description

2750-441: The substance of the lung. 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 . Elastin gives the necessary elasticity and resilience required for the persistent stretching involved in breathing, known as lung compliance . It

2805-467: The terminal bronchioles gives them an alternative name of membranous bronchioles . The conducting zone of the respiratory tract ends at the terminal bronchioles when they branch into the respiratory bronchioles. This marks the beginning of the terminal respiratory unit called the acinus which includes the respiratory bronchioles, the alveolar ducts, alveolar sacs , and alveoli. An acinus measures up to 10 mm in diameter. A primary pulmonary lobule

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2860-451: 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),

2915-464: The walls and alveolar septa . Type I cells provide 95% of the surface area of each alveoli and are flat (" squamous "), and Type II cells generally cluster in the corners of the alveoli and have a cuboidal shape. Despite this, cells occur in a roughly equal ratio of 1:1 or 6:4. Type I are squamous epithelial cells that make up the alveolar wall structure. They have extremely thin walls that enable an easy gas exchange. These type I cells also make up

2970-400: Was driven into the lungs by the pharyngeal muscles via buccal pumping , a mechanism still seen in amphibians. In humans, the primary muscle that drives breathing is the diaphragm . The lungs also provide airflow that makes vocalisation including 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

3025-469: Was on May 31 1915 in a German offensive in Ypres . The mixture was chlorine-phosgene, with 95% and 5%. This article related to weaponry is a stub . You can help Misplaced Pages by expanding it . Lungs The lungs are the primary organs of the respiratory system in many animals, including humans. In mammals and most other tetrapods , two lungs are located near the backbone on either side of

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