Myasthenia gravis is a chronic autoimmune disorder that affects the neuromuscular junction. The body's own antibodies block acetylcholine from acting on the muscle, so the muscle cannot get the "contract" signal. This causes fatigue, weakening and paralysis of skeletal muscles. Memory hook: "Grave (gravis) attack by your OWN immune army on the junction."
In myasthenia gravis, the body's own antibodies attack receptors at the neuromuscular junction, blocking acetylcholine signalling so skeletal muscle cannot contract, causing fatigue and paralysis.
Your doubts, answered
Is myasthenia gravis autoimmune or genetic?
It is AUTOIMMUNE, not genetic. The body's own immune system attacks the neuromuscular junction. NEET often traps you here: muscular dystrophy is the genetic (inherited) one; myasthenia gravis is the autoimmune one. Do not mix them.
What is the difference between myasthenia gravis and muscular dystrophy?
Myasthenia gravis = autoimmune, attacks the neuromuscular junction, causes fatigue and paralysis of skeletal muscle. Muscular dystrophy = genetic (inherited), causes progressive degeneration of the skeletal muscle itself. One is an immune problem at the junction; the other is a gene problem in the muscle.
Which junction is affected in myasthenia gravis?
The neuromuscular junction (also called the motor end plate). This is where the motor neuron meets the sarcolemma of the muscle fibre and releases acetylcholine. In myasthenia gravis the signal transfer here is blocked.
Why does myasthenia gravis cause muscle fatigue and weakness?
The neurotransmitter acetylcholine normally crosses the neuromuscular junction to start muscle contraction. In myasthenia gravis, antibodies interfere at this junction, so fewer signals reach the muscle. The muscle gets tired quickly and becomes weak, and in severe cases paralysed.
Is myasthenia gravis the same as tetany?
No. Tetany is caused by LOW calcium (Ca2+) in body fluid, giving rapid wild spasms. Myasthenia gravis is an autoimmune junction disorder giving weakness and paralysis. Different cause, opposite symptom (weakness vs spasm).
⚠️ The NEET trap ✗ Myasthenia gravis is a genetic (inherited) disorder that degenerates muscle. ✓ Myasthenia gravis is AUTOIMMUNE and affects the neuromuscular junction. The genetic muscle-degeneration disorder is muscular dystrophy. NEET repeatedly reverses these two labels in match-the-column questions. 🧠 Autoimmune vs genetic swap
Real NEET questions
2021
Chronic auto immune disorder affecting neuromuscular junction leading to fatigue, weakening and paralysis of skeletal muscle is called as:
A · Myasthenia gravis ✓
B · Gout
C · Arthritis
D · Muscular dystrophy
Solution: Myasthenia gravis is the autoimmune disorder that targets the neuromuscular junction, producing fatigue, weakening and paralysis of skeletal muscle. Gout and arthritis are joint disorders; muscular dystrophy is genetic. NCERT Ch 17: 'Myasthenia gravis: Auto immune disorder affecting neuromuscular junction...'.
2019
Which of the following diseases is an autoimmune disorder?
A · Myasthenia gravis ✓
B · Arthritis
C · Osteoporosis
D · Gout
Solution: Myasthenia gravis is autoimmune. Arthritis is joint inflammation, osteoporosis is age-related bone loss (low estrogen), and gout results from uric acid crystal accumulation. None of these three is autoimmune.
2022
Which of the following is a correct match for disease and its symptoms?
A · Arthritis - Inflamed joints ✓
B · Tetany - high Ca2+ level causing rapid spasms
C · Myasthenia gravis - Genetic disorder resulting in weakening and paralysis of skeletal muscle
D · Muscular dystrophy - An autoimmune disorder causing progressive degeneration of skeletal muscle
Solution: Only 'Arthritis - Inflamed joints' is correct. Tetany is caused by LOW Ca2+ (not high). Myasthenia gravis is AUTOIMMUNE (not genetic). Muscular dystrophy is GENETIC (not autoimmune). This question is the classic NEET reversal trap.
Solved Locomotion and Movement NEET PYQs
Try the real previous-year questions from this chapter — each with the answer and a full solution.
A chronic autoimmune disorder affecting the neuromuscular junction, leading to fatigue, weakening and paralysis of skeletal muscle (NCERT Ch 17).
Which neurotransmitter is linked to myasthenia gravis?
Acetylcholine. It normally carries the signal across the neuromuscular junction to start contraction; in myasthenia gravis this transfer is disrupted.
Is myasthenia gravis inherited?
No. It is autoimmune, not inherited. The inherited (genetic) muscle disorder in NCERT is muscular dystrophy.
Which muscles are affected in myasthenia gravis?
Skeletal (voluntary) muscles, because the neuromuscular junction supplies skeletal muscle fibres.
How is myasthenia gravis different from osteoporosis?
Myasthenia gravis is an autoimmune muscle-junction disorder. Osteoporosis is an age-related bone disorder (decreased bone mass, often from low estrogen). They belong to different systems.
