Neuro Muscular Junction (NMJ) Quiz

Neuro Muscular Junction (NMJ)

Definition

• Site where motor neuron terminals release neurotransmitters to stimulate muscle contraction
• Also known as neuromuscular synapse or myoneural junction

Structure

• Presynaptic Terminal: Motor neuron terminal that releases neurotransmitters
  • Contains synaptic vesicles filled with acetylcholine (ACh)
• Synaptic Cleft: Small gap (20-30 nm) between presynaptic terminal and muscle fiber
• Postsynaptic Membrane: Muscle fiber membrane with ACh receptors

Neurotransmission

• Release of Neurotransmitters: ACh is released from synaptic vesicles into synaptic cleft
• Binding of ACh: ACh binds to nicotinic ACh receptors on postsynaptic membrane
• Muscle Contraction: Binding of ACh triggers muscle contraction through muscle action potential

Functions

• Muscle Contraction: NMJ enables muscle contraction in response to neural stimulation
• Motor Control: NMJ plays a crucial role in motor control and coordination

Diseases and Disorders

• Myasthenia Gravis: Autoimmune disorder where immune system attacks ACh receptors
• Lambert-Eaton Syndrome: Autoimmune disorder where immune system attacks presynaptic terminal proteins
• Botulism: Bacterial toxin that inhibits ACh release, leading to muscle weakness and paralysis

Neuro Muscular Junction (NMJ)

Definition

• The site where motor neuron terminals release neurotransmitters to stimulate muscle contraction
• Also known as neuromuscular synapse or myoneural junction

Structure

• The presynaptic terminal contains synaptic vesicles filled with acetylcholine (ACh)
• The synaptic cleft is a small gap (20-30 nm) between the presynaptic terminal and the muscle fiber
• The postsynaptic membrane has ACh receptors on the muscle fiber membrane

Neurotransmission

• ACh is released from synaptic vesicles into the synaptic cleft through exocytosis
• ACh binds to nicotinic ACh receptors on the postsynaptic membrane, causing a conformational change
• The binding of ACh triggers muscle contraction through muscle action potential

Functions

• The NMJ enables muscle contraction in response to neural stimulation
• The NMJ plays a crucial role in motor control and coordination

Diseases and Disorders

• Myasthenia Gravis is an autoimmune disorder where the immune system attacks ACh receptors, leading to muscle weakness and fatigue
• Lambert-Eaton Syndrome is an autoimmune disorder where the immune system attacks presynaptic terminal proteins, leading to muscle weakness and fatigue
• Botulism is a bacterial toxin that inhibits ACh release, leading to muscle weakness and paralysis