National Board of Chiropractic Examiners (NBCE) Practice Test 2025 - Free Chiropractic Practice Questions and Study Guide

Myasthenia gravis, rheumatoid arthritis, and multiple sclerosis are all classified as autoimmune disorders. An autoimmune disorder arises when the immune system mistakenly attacks the body's own tissues, believing them to be foreign invaders.

Myasthenia gravis specifically affects the communication between nerves and muscles, leading to muscle weakness and fatigue. In this condition, antibodies attack the acetylcholine receptors at the neuromuscular junction, inhibiting muscle contraction.

Rheumatoid arthritis primarily affects the joints, where it causes inflammation and pain due to the immune system attacking the synovium — the lining of the joints. This chronic inflammation can lead to joint damage and loss of function.

Multiple sclerosis involves the immune system attacking the myelin sheath that covers nerve fibers in the central nervous system. This demyelination leads to various neurological symptoms, depending on the areas where the damage occurs.

Since all three options represent distinct autoimmune mechanisms and disorders, the most accurate choice is that they all classify as autoimmune disorders. Thus, claiming only myasthenia gravis is classified as such is incomplete.