1 Sheep heart - The sheep heart is very similar in size and shape to the human heart - slightly larger than the average human heart, but otherwise very similar. 2 Sheep eye - The sheep eye is identical to the human eye in all major respects. 3 Sheep brain - The sheep brain has the same basic plan as all mammalian brains, including humans. Compared to a human brain, the sheep brain has a relatively smaller cerebral cortex and consequently a relatively smaller overall size. The other major parts are identical in terms of gross anatomy.