Imithambo yegazi ekuhamba kuyo igazi ilise entliziyweni ngoonobuyisa. Yona imithambo iya ivuleka isiba mikhulu xa isiya isondela entliziyweni. Xa kubuyiselwa igazi entliziyweni le mithambo ingoonobuyisa iya ivuleka ngokuya isondela entliziyweni, ize iye incipha ngokuya isiba kude nentliziyo, le ndawo inciphileyo ke apha koonobuyisa kuthiwa zii-venules.