The brain of an animal and the brain of a human are composed of the same structures and have the same components, but some vary in size in different animals.
The human brain is made up of approximately 100-billion nerve cells. The nerve cells have three basic parts: the cell body, the axon, and the dendrites. The brain also has thefollowing parts: the brainstem, which controls the reflexes and the automatic functions, limb movements, and visceral functions; the cerebellum, which coordinates limb movements; the hypothalamus, which controls visceral functions such as feeding, drinking, and aggression; and the cerebrum, which integrates information from all the sense organs, initiates motor functions, and controls emotions.
The lower brain consists of the spinal cord, brainstem, and diencephalons. Within each .
of these structures are nuclei that are used for particular functions such as breathing, heart-rate .
regulation, and sleep. These cell bodies are called the medulla, the pons, the midbrain, the thalamus, and the hypothalamus.
Animal brains also have the brainstem, the cerebellum, hypothalamus and pituitary gland, .
and the cerebrum. However, in different animals, the cortex gets bigger, takes up a larger portion of the total brain and becomes folded. .
The bigger cortex takes on additional higher-order functions, such as information processing, speech, thought and memory. When a split-brain study was done in an animal, in which the .
optical chiasm and corpus callosum were cut, the animal not only had a split-brain, but also an eye connected to one hemisphere. Only the left side of the brain could be taught. In humans, split-brain studies imply do not prove that ordinary people have two minds. The left brain can easily pick out an object placed in the right hand if the object is easy to identify. The left brain has difficulty with amorphous shapes, but the right brain could easily identify amorphous objects.
