Definitions | myasthenia-gravis

Definitions:

Myasthenia Gravis (MG): a disease that is characterized by the weakening of muscles due to an autoimmune response against the acetylcholine receptors in the neuromuscular junction.

Immune system: the system in the body that responds to foreign substances to protect the body.
Neuromuscular junction: the junction of a nerve and muscle cell at which the electrical action potential is translated to a chemical signal for muscle function.
Thymus: a glandular lymphoid tissue that develops T cells for immune response.

Acetylcholine: a neurotransmitter released from the presynaptic membrane and diffuses across the synaptic cleft, binding to acetylcholine receptors to create the end plate potential.
End plate potential: the potential created on the muscle cell membrane that is caused by acetylcholine and leads to depolarization.
T-tubules: carriers of the signal throughout the muscle cell.
Sarcoplasmic reticulum: the endoplasmic reticulum of skeletal muscle cells. It stores calcium for use in muscle contraction.
ATP (Adenosine Triphosphate): is a phosphorylated nucleotide with three phosphate groups and one adenosine. It is known for its hydrolysis and its’ ability in many metabolic (energy) related body functions including muscle contraction.
Diffusion: process by which molecules move through a fluid or membrane from high to low concentration.
Acetylcholinesterase: an enzyme that hydrolyzes acetylcholine.

B Cell: lymphocytes that differentiate in the bone marrow and can form plasma, antibody secreting, or memory cells.
T Cell: lymphocytes that differentiate in the thymus and can be made into helper, cytotoxic or regulatory T cell to aid in immune function and response.
Peripheral Lymphoid Organs: lymph tissues other than the thymus and bone marrow, such as those in the spleen, gut, tonsils, etc.
Innate Immune Response: non-specific, first immune response.
Adaptive Immune Response: specific immune response.
Antibodies: proteins produced by B cells in the immune system to tag and/or block antigens.
Antigens: anything that is foreign to the body and causes an immune response.
Helper T cells: a T cell that “help” the immune system efficiency and activate B cells to differentiate and produce antibodies.
Cytotoxic T cells: a T cell with CD8 that mounts a cell-mediated response to antigens.
Major histocompatibility complex: complex created by cells to present antigens on the cell membrane for identification by T cells.
Complement: immune system response activated by antibodies to destroy Acetylcholine receptors.

Autoimmune disorder: a disorder in which the host recognizes itself as foreign and mounts an immune response.
Voltage gated channels: ion channels that function based on voltage potentials allowing ions to flow.

Ptosis: a sagging or prolapse of an organ or part, especially a drooping of the upper eyelid.
MG Crisis: involves weakness in the respiratory muscles that can lead to respiratory failure.
Oropharyngeal muscles: muscles of the pharynx and mouth region.
Thymoma: tumor found in the thymus.

Cholinesterase Inhibitors: drugs that inhibit the function of acetylcholinesterase and allowing acetylcholine to remain at the end plate longer.
Prednisone: most common corticosteroid used in treatment of MG.
Thymectomy: surgical procedure to remove the thymus gland. May be beneficial in MG to reduce CD4 T-cells.