In ihumans, ithe
imain iorgans iresponsible
ifor irespiration iare
ipresent iin ithe
ithoracic icavity. iIn ithe ithorax
iregion, ithe irib
icage iand ia idome ishaped
ifibrous itissue iknown
ias ithe idiaphragm
iare iobserved. ipresent
iwithin ithe irib
icage ior ithe iplural imembranes,
iwhich iincludes ithe
ilungs. iThe iright
ilung iis idivided iinto ithree
ilobes, ithe iright
isuperior, iright imiddle,
iand ithe iright
iinferior ilobe. iThe
ileft ilung iis ismaller iand
ihas ionly itwo
ilobes, ithe ileft
isuperior iand ithe
ileft iinferior ilow
iBoth ithe ilungs
iare iassociated iexternally
iwith ismall itubular
ibronchitis, iwhich iunite
iand iextend iinto
ithe itrachea. iThe
itrachea ihas iincomplete
iC ishaped irings
iof icartilage, iwhich
iprevent ithe itrachea
iwall ifrom icollapsing.
iThe itrachea igoes iinto ithe ifirings
iwhrere iis iconnected ito ithe
inostrils. iAs iwe ibreathe iin iair, ithe
ioxygen imolecules ienter
ithe inostrils iand
itravel idownwards ithrough
ithe ipharynx iand
itrachea to ifinally ireach
ithe ibronchitis.
From ieach ibronchitis, ioxygen itravels iinto ithe ilungs. iWithin ithe ilungs, ithe ibronchus idivides irepeatedly ito iform ibronchioles. iOxygen itravels ithrough ithese ibronchioles iand ireaches ithe ialveoli iline, ieach iof iwhich iis isurrounded iby ia inetwork iof icapillaries. isection iof ione ialveoli ilive ishows ithe ipresence iNumerous ialveoli ilarge ichambers iwith ipores.
Blood containing iRBC iis iseen iflowing ithrough ithe icapillaries, ithe ioxygen imolecules ifrom ithe
ialveoli idiffuse iinto ithe icapillary iand ithen iget iabsorbed iby ithe ibluish ipurple iRBC. iThis icauses ioxygenation iof ithe iRBC, iand ia itransition iin itheir icolor ifrom ibluish ipurple ito ired iis iobserved ithe iblood imoving iinto ithe ialveolar sacs iicontains RBC iand icarbon idioxide imolecules. These imolecules iare ireleased iinto ithe ialveolar sacs, the icarbon idioxide icollects iin ithe ialveoli ilarge ichamber iand ithen ifrom ithe ialveolar sacs, i iit itravels ithrough ithe ibronchioles into ithe ibronchus.
Which ifinally ireaches ithe itrachea, iand iit's ibreathe idown ithrough ithe inostrils. iSo ithe iprocess iof ibreathing iin iair iwhich in ioxygen iis icalled iinhalation. iAfter ithe ishrinking iof ithe imuscular idiaphragm, ithe ilungs increase in sizeiiand ithe iair ifills iin, iresulting iin ithe iinflation iof ithe ialveoli. iDuring iexhalation, ithe idiaphragm imoves iup iand ithe ilungs shrink s. iThus ithe ialveoli ideflate icausing ithe iair ito ibe iforced iout. iThis iexhaled iair iis iwhich iin icarbon idioxide. iThis iprocess iof iinhalation iand iexhalation iis iknown ias irespiration which iis iapproximately i20 itimes iper iminute.
