Discovering Diseases

Question 1

What is the end-plate?

Answer 1

The neuro muskular junction where a motor neuron axon terminal makes close contact with the skeletal muscle fiber which it supplies

Question 2

What diseases affect NMJ level?

Answer 2

Myastenia gravis
Tetanus
Botulism

Question 3

What are the basic concepts of NMJ-skeletal muscle?

Answer 3

Release of ACh
Safetyfactor (more ACh is released than needed)
Anatomy and histology of the nicotinic ACh receptor (nAChR)

Question 4

What is Myasthenia Gravis and what are its effects?

Answer 4

A generalized neuropathy (failure in neuromuscular transmission)
Autoimmune disease
Leads to a decrease in nr of nAChR at neuromuscular junction of skeletal muscle due to the production of circulating anti nAChR antibodies-structural deficiency of nAChR in NMJ- inhibiting the excitatory effects of ACh on nAChR
Leads to muscle weakness

Question 5

What are the symptoms of Myastenia Gravis?

Answer 5

Muscle weakness and fatigue, increase with activity an decrease with rest
Variable evolution
Difficulties swallowing and chewing
Megaesophagus (enlarged esophagus) and Thymoma (thymic tumor, produced antibodies anti nAChR)

Question 6

What can be used to diagnose Myastenia Gravis?

Answer 6

Tensilon response test
A AChesterase inhibitor (edrophonium, brand name tensilon) is given as shows effect within 20-90 sek. The drug allows ACh to ackumulate by inhibiting AChesterases

Question 7

What is tetanus and What is its effects?

Answer 7

Caused by tetanus toxin (Tetanospasmin) a neurotoxin produced by clostridium tetani
Causes spastic paralysis

Question 8

What are the symptoms of tetanus?

Answer 8

Tetanus toxin blocks the inhibitory neurotransmitter Glycine or GABA and thereby the muscles contract without relaxation=continous contraction
Affects agonist and antagonist muscles simultanously

Question 9

What is botulism and its effects?

Answer 9

Botulinum toxin is a neurotoxin that is produced by clostridium botulinum
Causing flaccid paralysis

Question 10

What are the symptoms of botulism?

Answer 10

Botulinum toxin blocks the release of ACh (also blocks the cholinergic synapses of ANS)
The blocking of ACh makes it unable for muscles to contract in the region of the nerve terminal-flaccid paralysis