BreathingBreathing (respiring or ventilating) is the rhythmic process of inhaling air into the lungs providing oxygen, and exhaling the air removing carbon dioxide, in the gas exchange process. All aerobic organisms require oxygen for cellular respiration, which extracts energy from food and produces carbon dioxide as a waste product.Respiration (physiology)In physiology, respiration is a biological process that facilitates the transport of oxygen from the outside environment to bodily tissues and the removal of carbon dioxide of an organism using a respiratory system. The physiological definition of respiration differs from the biological definition of cellular respiration, which is a metabolic process by which an organism obtains energy (in the form of ATP and NADPH) by oxidizing nutrients and releasing waste products.
Carbon dioxideCarbon-oxygen gasNames IUPAC nameCarbon dioxideOther names Carbonic acid gasCarbonic anhydrideCarbonic dioxideCarbonic oxideCarbon(IV) oxideMethanedioneR-744 (refrigerant)R744 (refrigerant alternative spelling)Dry ice (solid phase)Identifiers CAS Number124-38-93D model (JSmol)Interactive imageInteractive imageBeilstein Reference1900390 ChEBICHEBI:16526ChEMBLChEMBL1231871ChemSpider274ECHA InfoCard100.004.271EC Number204-696-9E numberE290 (preservatives)Gmelin Reference989 KEGGD00004MeSHCarbon+dioxidePubChemCID280RTECS numberFF6400000UNII142M471B3JUN number1013 (gas), 1845 (solid) CompTox Dashboard(EPA)DTXSID4027028InChIInChI=1S/CO2/c2-1-3Key: CURLTUGMZLYLDI-UHFFFAOYSA-NInChI=1/CO2/c2-1-3Key: CURLTUGMZLYLDI-UHFFFAOYAOSMILESO=C=OC(=O)=OProperties Chemical formulaCO2Molar mass44.009 g·mol Appearance Colorless gas OdorLow concentrations: noneHigh concentrations: sharp; acidicDensity1562 kg/m (solid at 1 atm (100 kPa) and −78.5 °C (−109.3 °F))1101 kg/m (liquid at saturation −37 °C (−35 °F))1.977 kg/m (gas at 1 atm (100 kPa) and 0 °C (32 °F))Critical point (T, P) 304.128(15) K (30.978(15) °C), 7.3773(30) MPa (72.808(30) atm) Sublimationconditions194.6855(30) K (−78.4645(30) °C) at 1 atm (0.101325 MPa) Solubility in water1.45 g/L at 25 °C (77 °F), 100 kPa (0.99 atm) Vapor pressure5.7292(30) MPa, 56.54(30) atm (20 °C (293.15 K)) Acidity (pKa) Carbonic acid:pKa1 = 3.6pKa1(apparent) = 6.35pKa2 = 10.33 Magnetic susceptibility (χ)−20.5·10 cm/mol Thermal conductivity0.01662 W·m·K (300 K (27 °C; 80 °F)) Refractive index (nD)1.00045 Viscosity14.90 μPa·s at 25 °C (298 K)70 μPa·s at −78.5 °C (194.7 K)Dipole moment0 D Structure Crystal structureTrigonal Point groupD∞hMolecular shapeLinearThermochemistry Heat capacity(C)37.135 J/(K·mol) Std molarentropy(S298)214 J·mol·K Std enthalpy offormation(ΔfH298)−393.5 kJ·mol Pharmacology ATC codeV03AN02 (WHO) Hazards GHS labelling: PictogramsSignal wordWarningHazard statementsH280, H281Precautionary statementsP282, P336+P317, P403, P410+P403NFPA 704 (fire diamond) 200SALethal dose or concentration (LD, LC): LCLo (lowest published)90,000 ppm (162,000 mg/m) (human, 5 min) NIOSH (US health exposure limits): PEL (Permissible)TWA 5000 ppm (9000 mg/m) REL (Recommended)TWA 5000 ppm (9000 mg/m), ST 30,000 ppm (54,000 mg/m) IDLH (Immediate danger)40,000 ppm (72,000 mg/m) Safety data sheet (SDS) Sigma-AldrichRelated compounds Other anionsCarbon disulfideCarbon diselenideCarbon ditellurideOther cationsSilicon dioxideGermanium dioxideTin dioxideLead dioxideTitanium dioxideZirconium dioxideHafnium dioxideCerium dioxideThorium dioxideRelated carbonoxidesSee OxocarbonRelated compoundsCarbonic acidCarbonyl sulfideCarbonyl selenideSupplementary data page Carbon dioxide (data page)Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).N verify ( ?)Peripheral chemoreceptorPeripheral chemoreceptors (of the carotid and aortic bodies) are so named because they are sensory extensions of the peripheral nervous system into blood vessels where they detect changes in chemical concentrations. As transducers of patterns of variability in the surrounding environment, carotid and aortic bodies count as chemosensors in a similar way as taste buds and photoreceptors.Respiratory rateThe respiratory rate is the rate at which breathing occurs; it is set and controlled by the respiratory center of the brain. A person's respiratory rate is usually measured in breaths per minute.
Blood gas tensionBlood gas tension refers to the partial pressure of gases in blood. There are several significant purposes for measuring gas tension. The most common gas tensions measured are oxygen tension (PxO2), carbon dioxide tension (PxCO2) and carbon monoxide tension (PxCO). The subscript x in each symbol represents the source of the gas being measured: "a" meaning arterial, "A" being alveolar, "v" being venous, and "c" being capillary.
Cellular respirationCellular respiration is the process of oxidizing biological fuels using an inorganic electron acceptor, such as oxygen, to drive production of adenosine triphosphate (ATP), which stores chemical energy in a biologically accessible form.
PCO2pCO2, or PCO2{\displaystyle P_{{\ce {CO2}}}}, depending on the context and use, is the partial pressure of carbon dioxide (CO2). It can refer to bloodphysiology or to atmospheric chemistry and geochemistry, including meteorology, climate science, hydrochemistry, oceanography, and limnology to describe the fractional pressure of CO2 as a function of its concentration in gas or dissolved phases.
OxygenChemical element with atomic number 8 (O)–↑O↓Snitrogen ← oxygen → fluorine
PhysiologyPhysiology (; from Ancient Greek (phúsis)'nature, origin' and (-logía)'study of') is the scientific study of functions and mechanisms in a living system. As a subdiscipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out chemical and physical functions in a living system.
LungPrimary organ of the respiratory systemThe 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 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.
ArteryAn artery (from Greek ἀρτηρία (artēríā)) is a blood vessel in humans and most other animals that takes oxygenated blood away from the heart in the systemic circulation to one or more parts of the body. Exceptions that carry deoxygenated blood are the pulmonary arteries in the pulmonary circulation that carry blood to the lungs for oxygenation, and the umbilical arteries in the fetal circulation that carry deoxygenated blood to the placenta.*As an Amazon Associate I earn from qualifying purchases.