View source for Biology:Respiration (physiology)

{{Short description|Exchange of gases between environment and tissues}}
In [[Biology:Physiology|physiology]],''' respiration''' is the movement of oxygen from the outside environment to the cells within [[Biology:Tissue|tissue]]s, and the removal of [[Chemistry:Carbon dioxide|carbon dioxide]] in the opposite direction that's to the environment.<ref name=":0">{{Cite book|last=Hinic-Frlog|first=Sanja|title=Introductory Animal Physiology|publisher=Pressbooks (CC BY 4.0)|year=2019|isbn=|location=University of Toronto Mississauga|pages=40–59}}</ref>

The physiological definition of respiration differs from the [[Biology:Cellular respiration|biochemical definition]], which refers to a metabolic process by which an organism obtains energy (in the form of ATP and NADPH)<ref>{{Cite book |url= |title=Molecular Biology of the Cell |publisher=Garland Science |year=2002 |isbn=0-8153-3218-1 |veditors=Alberts B, Johnson A, Lewis J, Raff M, Roberts K, Walter P |edition=4th |location=New York |chapter=NADH and NADPH Are Important Electron Carriers |chapter-url=https://www.ncbi.nlm.nih.gov/books/NBK26838/#A273 |via=NCBI Bookshelf}}</ref> by oxidizing nutrients and releasing waste products. Although physiologic respiration is necessary to sustain cellular respiration and thus life in animals, the processes are distinct: cellular respiration takes place in individual cells of the organism, while physiologic respiration concerns the [[Physics:Diffusion#Diffusion vs. bulk flow diffusion|diffusion]] and transport of [[Biology:Metabolite|metabolite]]s between the organism and the external environment.

Gas exchanges in the lung occurs by ventilation and perfusion.<ref name=":0" /> Ventilation refers to the in and out movement of air of the lungs and perfusion is the circulation of blood in the pulmonary capillaries.<ref name=":0" /> In mammals, physiological respiration involves respiratory cycles of [[Biology:Inhalation|inhaled]] and [[Biology:Exhalation|exhaled]] [[Physics:Breathing|breaths]]. Inhalation (breathing in) is usually an active movement that brings air into the [[Medicine:Lung|lung]]s where the process of [[Physics:Gas exchange|gas exchange]] takes place between the air in the alveoli and the [[Biology:Blood|blood]] in the [[Biology:Pulmonary circulation|pulmonary]] [[Biology:Capillary|capillaries]]. Contraction of the diaphragm muscle cause a pressure variation, which is equal to the pressures caused by elastic, resistive and inertial components of the respiratory system. In contrast, exhalation (breathing out) is usually a passive process, though there are many exceptions: when generating functional overpressure (speaking, singing, humming, laughing, blowing, snorting, sneezing, coughing, powerlifting); when exhaling underwater (swimming, diving); at high levels of physiological exertion (running, climbing, throwing) where more rapid gas exchange is necessitated; or in some forms of breath-controlled [[Philosophy:Meditation|meditation]]. Speaking and singing in humans requires sustained breath control that many mammals are not capable of performing. 

The process of breathing does not fill the alveoli with atmospheric air during each inhalation (about 350 ml per breath), but the inhaled air is carefully diluted and thoroughly mixed with a large volume of gas (about 2.5 liters in adult humans) known as the [[Medicine:Functional residual capacity|functional residual capacity]] which remains in the lungs after each exhalation, and whose gaseous composition differs markedly from that of the ambient air. Physiological respiration involves the mechanisms that ensure that the composition of the [[Medicine:Functional residual capacity|functional residual capacity]] is [[Homeostasis#Levels of blood gases|kept constant]], and equilibrates with the gases dissolved in the pulmonary capillary blood, and thus [[Biology:Extracellular fluid#Function|throughout the body]]. Thus, in precise usage, the words ''breathing'' and ''ventilation'' are hyponyms, not synonyms, of ''respiration''; but this [[Social:Linguistic prescription|prescription]] is not consistently followed, even by most [[Medicine:Health care provider|health care provider]]s, because the term ''[[Respiratory rate|respiratory rate]]'' (RR) is a well-established term in [[Medicine:Health care|health care]], even though it would need to be consistently replaced with ''ventilation rate'' if the precise usage were to be followed. During respiration the C-H bonds are broken by oxidation-reduction reaction and so carbon dioxide and water are also produced. The cellular energy-yielding process is called cellular respiration.

== Classifications of respiration ==
There are several ways to classify the physiology of respiration:
{{Prose|section|date=February 2014}}

=== By species ===
* [[Biology:Aquatic respiration|Aquatic respiration]]
* Buccal pumping
* [[Biology:Cutaneous respiration|Cutaneous respiration]]
* Intestinal respiration
* Respiratory system

=== By mechanism ===
* [[Physics:Breathing|Breathing]]
* [[Physics:Gas exchange|Gas exchange]]
* Arterial blood gas
* Control of respiration
* Apnea

=== By experiments ===
* Huff and puff apparatus
* [[Medicine:Spirometry|Spirometry]]
* Selected ion flow tube mass spectrometry

=== By intensive care and emergency medicine ===
* CPR
* [[Medicine:Mechanical ventilation|Mechanical ventilation]]
* [[Medicine:Intubation|Intubation]]
* [[Medicine:Negative pressure ventilator|Iron lung]]
* [[Medicine:Intensive care medicine|Intensive care medicine]]
* [[Biology:Liquid breathing|Liquid breathing]]
* ECMO
* [[Medicine:Oxygen toxicity|Oxygen toxicity]]
* [[Medicine:Medical ventilator|Medical ventilator]]
* Life support
* [[Medicine:General anaesthesia|General anaesthesia]]
* Laryngoscope

=== By other medical topics ===
* Respiratory therapy
* [[Chemistry:Breathing gas|Breathing gas]]es
* Hyperbaric oxygen therapy
* [[Medicine:Hypoxia (medical)|Hypoxia]]
* Gas embolism
* [[Medicine:Decompression sickness|Decompression sickness]]
* [[Medicine:Barotrauma|Barotrauma]]
* [[Physics:Oxygen equivalent|Oxygen equivalent]]
* [[Medicine:Oxygen toxicity|Oxygen toxicity]]
* Nitrogen narcosis
* Carbon dioxide poisoning
* [[Medicine:Carbon monoxide poisoning|Carbon monoxide poisoning]]
* HPNS

==Additional images==
<gallery>
 Image:Surface tension and lung volume.jpg
 Image:Curvon1.jpg
 Image:Curvon2.jpg
 Image:IPP lungs.jpg
</gallery>

==See also==
* {{annotated link|Medicine:Diffusing capacity}}
* {{annotated link|Biology:Outline of biology}}

== References ==
{{Reflist}}
* Nelsons VCE Units 1–2 Physical Education. 2010 Cengage Copyright.

==External links==
* [http://oac.med.jhmi.edu/res_phys/index.HTML Overview] at [[Organization:Johns Hopkins University|Johns Hopkins University]]

== Further reading ==
* {{cite book | last = Nilsson | first = Goran E. | title = Respiratory Physiology of Vertebrates | publisher = Cambridge University Press | location = Cambridge | year = 2010 | isbn = 978-0-521-70302-4}}
* {{cite book | last = Randall | first = David | title = Eckert Animal Physiology | publisher = W.H. Freeman and CO | location = New York | year = 2002 | isbn = 0-7167-3863-5 | url-access = registration | url = https://archive.org/details/eckertanimalphys00rand }}, human biology 146149
* C.Michael Hogan. 2011. [http://www.eoearth.org/article/Respiration?topic=74360 ''Respiration''. Encyclopedia of Earth. Eds. Mark McGinley and C.J.Cleveland. National Council for Science and the Environment. Washington DC]

{{Respiratory physiology}}

[[Category:Excretion]]
[[Category:Respiration|*]]

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{{Sourceattribution|Respiration (physiology)}}