Final answer:
Multiple sclerosis (MS) is an autoimmune disease that affects the brain and spinal cord, resulting in inflammatory demyelination of nerve cells. This leads to lesions or foci in the central nervous system, causing a variety of symptoms including physical disability and cognitive deficits.
Step-by-step explanation:
Multiple sclerosis (MS) is an autoimmune central nervous system disease that affects the brain and spinal cord. MS is characterized by the inflammatory demyelination of nerve cells in the brain and spinal cord, resulting in foci or lesions. These lesions disrupt neuronal signaling and lead to a wide range of symptoms including physical disability, cognitive deficits, and psychiatric symptoms.