Study Question Eight

• Q8. Explain and understand clinical applications given in class and in independent reading.
• Multiple sclerosis (MS) affects the central nervous system, which includes the brain and spinal cord. In MS, the immune system mistakenly attacks the myelin, a protective sheath that surrounds nerve fibers, leading to inflammation and damage. This disruption slows or blocks electrical signals between the brain and the rest of the body, causing symptoms like muscle weakness, coordination issues, and sensory disturbances. Over time, this damage can lead to scar tissue (sclerosis), which further impairs nerve function.
• Amyotrophic lateral sclerosis (ALS) affects the central nervous system, targeting motor neurons in the brain and spinal cord. These motor neurons are responsible for controlling voluntary muscle movements. As ALS progresses, these neurons degenerate and die, leading to muscle weakness, atrophy, and loss of coordination. Unlike multiple sclerosis, ALS does not affect the myelin sheath; instead, it directly impacts the nerve cells themselves. This degeneration results in increasingly severe physical disabilities, while cognitive functions often remain intact.
• Myasthenia gravis is an autoimmune disorder that affects the communication between nerves and muscles. It targets the neuromuscular junction, where nerve endings release a chemical called ACh to stimulate muscle contraction. The immune system produces antibodies that block or destroy ACh receptors on muscle cells, preventing effective communication. As a result, affected muscles become weak and tire easily. This can impact various muscle groups, leading to difficulties in movement, swallowing, and breathing.
• Guillain-Barré syndrome (GBS) is an autoimmune condition that affects the peripheral nervous system. It occurs when the immune system mistakenly attacks the myelin sheath surrounding the nerves, leading to inflammation and damage. This disruption slows down or blocks nerve signals, causing symptoms like weakness, tingling, and paralysis that start in the legs and can ascend. The condition can progress quickly but is often temporary.