20. The Neuromuscular Junction Flashcards
Describe the neuromuscular junction
-Synapse between motor neuron and end plate of muscular fibre.
Describe 2 Neuromuscular junction disorders.
-Myasthenia gravis, autoantibodies bind to the acetylcholine receptors on the motor end plates blocking ACh so muscle activation is inhibited and the muscles will become weak. Small muscles are effected first like the eye muscles or throat with difficulty swallowing, end stages control of breathing may be hard and control of limbs will be effected
-Lambert-Eaton myasthenic syndrome, autoantibodies interfere with the calcium-dependant release of ACh from the presynaptic membrane and subsequently cause a reduced endplate potential on the postsynaptic membrane resulting in NMJ transmission failure
A patient with Myasthenia gravis disease is to receive immunosuppressive therapy this is effective because.
A: inhibits the breakdown of acetylcholine at the neuromuscular junction.
B: Stimulates the production of acetylcholine at the
C: Promotes the removal of antibodies that impair the transmission of impulses
D: Decreases the production of autoantibodies that attack the acetylcholine receptors
Answer D: Decreases the production of autoantibodies that attack the acetylcholine receptors
The neurotransmitter always used at the neuromuscular junction is:
A: Acetylcholine
B: Dopamine.
C: it depends on the type of muscle being innervated.
D: Noradrenaline
Answer A: Acetylcholine
An action potential arriving at the motor endplate causes release of:
A: Acetylcholine which traverses the neuromuscular junction
B: Sodium ions which bind to sodium receptors on the muscle membrane.
C: Calcium ions which initiate an action potential along the muscle fibre.
D: Noradrenaline which increase muscle metabolic activity.
E: None of the above.
Answer A: Acetylcholine which traverses the neuromuscular junction
A Nurse teaching a client with myasthenia gravis about the prevention of myasthenic and cholinergic crises. The effective measure is.
A: Eating large, well-balanced meals.
B: Doing muscle-strengthening exercise.
C: Taking medications on time to maintain therapeutic blood levels.
D: Doing all chores early in the day while less fatigued.
Answer C: Taking medications on time to maintain therapeutic blood levels.
