Oligodendrocytes and Schwann cells both create myelin sheaths for axons, however, oligodendrocytes function in the central nervous system and Schwann cells function in the peripheral nervous system.

Myelin sheathes function in insulating the neuron, and allows for much faster propogation of the action potential due to saltatory conduction. Loss of the myelin sheath would slow conduction of signals down the neural axon.

Pain perception is conducted to free nerve endings known as nociceptors, which are not myelinated.

There are two types of cells responsible for the myelination of axons throughout the nervous system. Oligodendrocytes myelinate the axons of neurons in the central nervous system. Schwann cells myelinate neurons in the peripheral nervous system. This question is referring to a nerve in the elbow, which would be in the peripheral nervous system.

Astrocytes are a type of glial cell primarily found in the blood-brain barrier. Dendritic cells play a role in the adaptive immune response, and are not considered part of the nervous system.

Ependymal cells, which line cerebral cavities and the central canal, produce cerebrospinal fluid (CSF). CSF is a colorless liquid that protects the brain and spinal cord against injury.

Microglia protect the central nervous system from microbes and debris of injured cells. Astrocytes, located in the central nervous system, provide structural support for neurons in addition to many other tasks involving nutrient and ion regulation. Oligodrendrocytes produce the myelin sheath around the axons of the central nervous system. Satellite cells are not found in the central nervous system, and therefore cannot produce CSF.

Both oligodendrocytes and Schwann cells produce and maintain myelin along axons. Oligodendrocytes are the most common glial cell type, and provide myelination for all neural axons in the central nervous system. Schwann cells provide myelination for neurons in the peripheral nervous system.

The medulla oblongata is responsible for autonomic functions, such as breathing rate and heart rate regulation. Dysfunction of the medulla oblongata could result in problems with breathing rhythm.

The cerebellum is responsible for coordination and balance. The hypothalamus regulates the fight-or-flight response, sex drive, thirst, and hunger. The midbrain is the center for auditory and visual signal relay to the cortex. The hippocampus functions in the retention of memories.

The MCAT contains minimal questions regarding brain anatomy, however, you should have an understanding of a select few structures, one of which is the corpus collosum. The corpus collosum is a bundle of neurons connecting the left and right brain, allowing communication between the left and right hemispheres. If these neurons were damaged somehow, the result would be split-brain syndrome, a condition in which the two halves of the brain do not communicate with one another.

The cerebral cortex is also referred to as the "higher brain." It acts to process thoughts and store memories. More basic, vital activities such as heart beat and breathing are controlled by other, less developed regions of the brain. Note that the hippocampus plays a role in creating memories, but most memories are stored in the cerebrum; this is the link between long term and short term memory storage.

The hypothalamus is responsible for cooling and heating mechanisms in the body, and thus is the correct answer. 

The cerebrum is responsible for higher brain functions, like conscious thought. The cerebellum is essential for balance and coordination. The thalamus is primarily responsible for integrating and coordinating sensory input to the brain.

The cerebellum is responsible for coordination and balance. Injury to the cerebellum can result in a loss of motor coordination.

The medulla oblongata controls autonomic activities, such as regulating heart and respiration rates. The hypothalamus regulates the fight-or-flight response, sex drive, thirst, and hunger. The midbrain is the center for auditory and visual signal relay to the cortex. The hippocampus functions in the retention of memories.