Ukuphefumla kuxa umoya ungena uphuma emiphungeni, okanye i-oxygen xa ihamba ngezinye ii-respiratory organs ezifana nee-gills. Kwii-organisms ezinemiphunga, ukuphefumla kuthiwa yi-ventilation, ezibandakanya zombini i-inhalation ne-exhalation. Ukuphefumla kulelinye lamalungu e- physiological respiration efunekayo ukuze kugcinwe ubomi. 

Ii-Aerobic organisms zeentaka, izilwanyana ezanyisayo, kunye nezirhubuluzayo – zifuna i-oxygen ukuze zikwazi ukukhulula i-energy eyakuthi ihambe nge-cellular respiration, ngenkqubo ekuthiwa yi-metabolism ye-energy-rich molecules njenge-glucose. Ukuphefumla yenye yeendlela zokuzisa  i-oxygen apho ifuneka khona emzimbeni kuze kususe ne- carbon dioxide.