Neuromuscular junction disease
Encyclopedia
Neuromuscular junction disease is a medical condition where the normal conduction through the neuromuscular junction
fails to function correctly.
, the End Plate Potential (EPP) fails to effectively activate the muscle fiber due to an autoimmune reaction against acetylcholine receptor
s, resulting in muscle weakness and fatigue.
Myasthenia gravis is caused most commonly by auto-antibodies against the acetylcholine receptor.
It has recently been realized that a second category of gravis is due to auto-antibodies against MuSK
.
A different condition, Lambert-Eaton myasthenic syndrome
, is usually associated with presynaptic antibodies to the voltage-dependent calcium channel
.
It is possible for these conditions to coexist.
prevent the release of acetylcholine, resulting in muscle paralysis
.
Neuromuscular junction
A neuromuscular junction is the synapse or junction of the axon terminal of a motor neuron with the motor end plate, the highly-excitable region of muscle fiber plasma membrane responsible for initiation of action potentials across the muscle's surface, ultimately causing the muscle to contract...
fails to function correctly.
Autoimmune
In diseases such as myasthenia gravisMyasthenia gravis
Myasthenia gravis is an autoimmune neuromuscular disease leading to fluctuating muscle weakness and fatiguability...
, the End Plate Potential (EPP) fails to effectively activate the muscle fiber due to an autoimmune reaction against acetylcholine receptor
Acetylcholine receptor
An acetylcholine receptor is an integral membrane protein that responds to the binding of acetylcholine, a neurotransmitter.-Classification:...
s, resulting in muscle weakness and fatigue.
Myasthenia gravis is caused most commonly by auto-antibodies against the acetylcholine receptor.
It has recently been realized that a second category of gravis is due to auto-antibodies against MuSK
Musk
Musk is a class of aromatic substances commonly used as base notes in perfumery. They include glandular secretions from animals such as the musk deer, numerous plants emitting similar fragrances, and artificial substances with similar odors. Musk was a name originally given to a substance with a...
.
A different condition, Lambert-Eaton myasthenic syndrome
Lambert-Eaton myasthenic syndrome
Lambert–Eaton myasthenic syndrome is a rare autoimmune disorder that is characterised by muscle weakness of the limbs...
, is usually associated with presynaptic antibodies to the voltage-dependent calcium channel
Voltage-dependent calcium channel
Voltage-dependent calcium channels are a group of voltage-gated ion channels found in excitable cells with a permeability to the ion Ca2+...
.
It is possible for these conditions to coexist.
Toxins
Various toxins, such as botulinum toxinBotulinum toxin
Botulinum toxin is a protein produced by the bacterium Clostridium botulinum, and is considered the most powerful neurotoxin ever discovered. Botulinum toxin causes Botulism poisoning, a serious and life-threatening illness in humans and animals...
prevent the release of acetylcholine, resulting in muscle paralysis
Paralysis
Paralysis is loss of muscle function for one or more muscles. Paralysis can be accompanied by a loss of feeling in the affected area if there is sensory damage as well as motor. A study conducted by the Christopher & Dana Reeve Foundation, suggests that about 1 in 50 people have been diagnosed...
.