Imithambo yegazi esebenza njengomzila okanye indlela yegazi eliphuma entliziyweni ibizwa ngokuba ngoo-nothumela. Aba nothumela ke baya bencipha ngokuya bebhekela beyishiya intliziyo. Bathi ke bakubabancinane ngokugqibeleleyo bajike ngoku babe zii-arterioles. Xa bezii-arterioles kulapho bathi baxhumane khona nemithanjana yomzimba ebizwa ngokuba zii-cappilaries.