An
organ is a distinct region of
cells within a multicelluar organism that perform a distinct function. Organs include the
heart,
lungs,
brain,
stomach,
spleen,
pancreas,
kidneys,
liver,
intestines,
uterus,
bladder etc. Some considered
skin as the largest organ on the human body.
Analogous structures exist on the sub-cellular level and are known as organelles.
See also : transplant, Artificial organ