Mbbs 1st year assignment on NMJ.

1. NEUROMUSCULAR
TRANSMITTER
BY :- RITESH KUMAR TRIPATHI
ROLL NO. :- 105
MBBS BATCH 2022

2. INTRODUCTION :
 It is the process responsible for the chemical transmission
of the electrical impulse from a nerve to the muscle in
order to produce muscle contraction.
 It is a site for many diseases and action for many
pharmacological drugs.
 Neuromuscular transmission can be divided into three
main parts : a presynaptic part ,the postsynaptic part and
an area between the nerve terminal and motor endplate.

3. EVENTS DURING NEUROMUSCULAR
TRANSMISSION
 Arrival of action potential at motor neuron terminal.
 Depolarisation of motor neuron terminal.
 Calcium ion influx into nerve terminal.
 Binding of synaptic vesicles to pre junctional membrane.
 Release of acetylcholine by exocytosis.
 Diffusion of acetylcholine through synaptic.
 Binding of acetylcholine with receptors on post junctional
membrane.
 Opening of ligand gated sodium channels and slow influx of
sodium.

4. EVENTS DURING NEUROMUSCULAR
TRANSMISSION
 Generation of end plate potential.
 End plate potential on reaching the firing level leads to the
opening of voltage gated sodium channels at extra junctional
region.
 Generation of muscle action potential.
 Metabolism of acetylcholine by choline esterase present on
the post junctional membrane.

6. MYASTHENIA GRAVIS
 It is a rare autoimmune disorder caused by formation of antibodies
against nicotinic acetyl choline receptors.
 In this disorder, the size of end plate potential is reduced therefore it is
more difficult to the muscle membrane to threshold and to produce
action potential.

7. Symptoms :
Weakness of the eye muscles (ocular
myasthenia)
Drooping of one or both eyelids (ptosis)
Blurred or double vision (diplopia)
Changes in facial expressions.
Difficulty swallowing.
Shortness of breath.
Impaired speech (dysarthria)

8.  TREATMENT :
 Cholinesterase inhibitors Medications such as pyridostigmine
(Mestinon, Regonal) enhance communication between nerves and
muscles. These medications aren't a cure, but they can improve
muscle contraction and muscle strength in some people.
• Corticosteroids. Corticosteroids such as prednisone inhibit the
immune system, limiting antibody production. Prolonged use of
corticosteroids, however, can lead to serious side effects, such as
bone thinning, weight gain, diabetes and increased risk of some
infections.
• Immunosuppressants. Your doctor might also prescribe other
medications that alter your immune system, such as azathioprine
(Azasan), cyclosporine (Sandimmune, Gengraf, others), methotrexate.
These drugs, which can take months to work, might be used with
corticosteroids.

9. THANK YOU!!