1. What is the purpose of the myelin sheath covering the axon of a neuron?
The myelin sheath is a protective covering that surrounds fibers called axons,
the long thin projections that extend from the main body of a nerve cell or
neuron. This sheath is composed of protein and lipids.
2. What are neurotransmitters? Give an example of one.
More than 30 substances are thought to be neurotransmitters, including
norepinephrine, acetylcholine, dopamine, histamine, and serotonin. Many of
these transmitters have more than one function.3 For example, norepinephrine in
the brain probably helps regulate mood, functions in dreaming sleep, and
maintains arousal. Some neurotransmitters are amino acids, including gamma-
aminobutyric acid (GABA), glutamic acid, and aspartic acid.
3. What is the name for the collection of nerve cells within the brainstem that
control our vital reflexes such as HR and RR?
The midbrain, medulla, and pons comprise the brain stem, which connects the
hemispheres of the brain, cerebellum, and spinal cord. A collection of nerve cell
bodies (nuclei) within the brain stem makes up the reticular formation. The
reticular formation is a large network of diffuse nuclei that control vital
reflexes, such as those controlling cardiovascular function and respiration. It is
essential for maintaining wakefulness and therefore is referred to as the reticular
activating system. Some nuclei within the reticular formation cause specific
motor movements.3
4. The cerebrum is broken down into 4 different lobes. What are those lobes and
what is the main function of each one?
There are four basic lobes that divide up the cerebral hemispheres. These have
been named for the bones of the skull that lie on top of them and include the
Frontal, Temporal, Parietal and Occipital lobes.