Utente:Mikialba/Sandbox2: differenze tra le versioni

Versione delle 10:28, 9 dic 2006

Versione delle 12:13, 9 dic 2006

Riga 14:

L'[[energia]] prodotta dalla [[respirazione cellulare]] richiede ossigeno e produce anidride carbonica. Nei piccoli [[organismo|organismi]], come i [[batterio|batteri]], questo processo di scambio di gas è svolto interamente dalla [[diffusione]] semplice. Nei grandi organismi, questo none è possibile; solo una bassa percentuale di cellule permettono di far entrare l'ossigeno tramite diffusione. La respirazione negli organismi [[multicellulari]] è possibile grazie ad un efficiente [[sistema circolatorio]], il quale trasporta i [[gas]] anche nelle parti più piccole e profonde del corpo, e al [[sistema respiratorio]], che coglie l'ossigeno dall'atmosfera e lo diffonde nel corpo, da dove viene distribuito rapidamente in tutto l'apparato circolatorio.

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In air-breathing vertebrates, respiration occurs in a series of steps. Air is brought into the animal via the airways — in reptiles, birds and mammals this often consists of the [[nose]]; the [[pharynx]]; the [[larynx]]; the [[trachea]]; the [[bronchus|bronchi]] and [[bronchiole]]s; and the terminal branches of the [[respiratory tree]]. The lungs of mammals are a rich lattice of [[Pulmonary alveolus|alveoli]], which provide an enormous surface area for gas exchange. A network of fine [[capillary|capillaries]] allows transport of [[blood]] over the surface of alveoli. Oxygen from the air inside the alveoli diffuses into the bloodstream, and carbon dioxide diffuses from the blood to the alveoli, both across thin alveolar [[membrane (biology)|membranes]]. The drawing and expulsion of air is driven by [[muscle|muscular]] action; in early [[tetrapod]]s, air was driven into the lungs by the [[Pharynx|pharyngeal]] muscles, whereas in [[reptile]]s, [[bird]]s and [[mammal]]s a more complicated [[musculoskeletal system]] is used. In the mammal, a large muscle, the [[diaphragm (anatomy)|diaphragm]] (in addition to the internal intercostal muscles), drive ventilation by periodically altering the intra-thoracic [[volume]] and [[pressure]]; by increasing volume and thus decreasing pressure, air flows into the airways down a pressure gradient, and by reducing volume and increasing pressure, the reverse occurs. During normal breathing, expiration is passive and no muscles are contracted (the diaphragm relaxes). Another name for this inspiration and expulsion of air is [[Ventilation (physiology)|ventilation]].

InNei air-breathingvertebrati, vertebrates,la respirationrespirazione occursavviene in auna seriesserie ofdi stepspassi. AirL'[[aria]] ispassa broughtper intole thevie animalrespiratorie via the airways- —nei in reptiles[[rettili]], birdsnegli and[[uccelli]] mammalse thisnei often[[mammiferi]] consistsconsistono of thenel [[nosenaso]]; thela [[pharynxfaringe]]; thela [[larynxlaringe]]; thela [[trachea]]; thei [[bronchusbronco|bronchi]] ande i [[bronchiolebronchiolo|bronchioli]]s; andinfine thevi terminalsono branchesgli ofultimi thebranchi [[respiratorydell'albero tree]]della respirazione, gli alveoli. The lungs of mammals are a rich lattice of [[Pulmonary alveolus|alveoli]], which provide an enormous surface area for gas exchange. A network of fine [[capillary|capillaries]] allows transport of [[blood]] over the surface of alveoli. Oxygen from the air inside the alveoli diffuses into the bloodstream, and carbon dioxide diffuses from the blood to the alveoli, both across thin alveolar [[membrane (biology)|membranes]]. The drawing and expulsion of air is driven by [[muscle|muscular]] action; in early [[tetrapod]]s, air was driven into the lungs by the [[Pharynx|pharyngeal]] muscles, whereas in [[reptile]]s, [[bird]]s and [[mammal]]s a more complicated [[musculoskeletal system]] is used. In the mammal, a large muscle, the [[diaphragm (anatomy)|diaphragm]] (in addition to the internal intercostal muscles), drive ventilation by periodically altering the intra-thoracic [[volume]] and [[pressure]]; by increasing volume and thus decreasing pressure, air flows into the airways down a pressure gradient, and by reducing volume and increasing pressure, the reverse occurs. During normal breathing, expiration is passive and no muscles are contracted (the diaphragm relaxes). Another name for this inspiration and expulsion of air is [[Ventilation (physiology)|ventilation]].

==Nonrespiratory functions==

Riga 54 ⟶ 55:

The first lungs, simple sacs that allowed the organism to gulp air under oxygen-poor conditions, evolved into the lungs of today's terrestrial vertebrates and into the [[gas bladder]]s of today's fish. The lungs of [[vertebrate]]s are [[homology (biology)|homologous]] to the [[gas bladder]]s of [[fish]] (but not to their [[gill]]s). The evolutionary origin of both are thought to be outpocketings of the upper intestines. This is reflected by the fact that the lungs of a [[fetus]] also develop from an outpocketing of the upper intestines and in the case of gas bladders, this connection to the gut continues to exist as the [[pneumatic duct]] in more "primitive" [[teleost]]s, and is lost in the higher orders. (This is an instance of correlation between [[ontogeny and phylogeny]].) There are no animals which have both lungs and a gas bladder.

==Voci correlate==

==Collegamenti esterni==

* [[Bronco]]

* [[BronchiteRespirazione]]

* [[PolmonologiaTumore del polmone]]

* [[Chirurgia cardiotoracica]]

* [[Ostruzione polmonare]]

* [[Liquido della respirazione]]

* [[Ventilazione meccanica]]