neuromuscular disorders Flashcards
Which muscles exert more force?
Proximal (think torque)
Break down the CNS
CNS
- brain
1) cerebral hemispheres
2) brainstem
3) cerebellum
- cord
1) cervical
2) thoracic
3) lumbo sacral & conus
Break down the PNS
PNS
- roots
- plexus
- nerves
- end organs
1) NMJ/ muscle
2) sensory organs
Components of NMJ
1) Presynaptic terminal with synaptic vesicles, mitochondria
2) Synaptic cleft
3) Postsynaptic membrane with neurotransmitter receptors
Roles of NMJ
NMJ transmits nerve impulses to skeletal muscle cells for voluntary contraction
Main neurotransmitter at the NMJ is
Acetylcholine
In Myastenia gravis, there are antibodies directed against
Ach receptors (AchRAb-acetylcholine receptor antibodies)
Treatment for Myasthenia Gravis
Acetylcholinesterase inhibitors
Pathology of myasthenia gravis
AchRAb-acetylcholine receptor antibodies is directed against the AChR. Fewer ACh binds to AChR, thus weaker muscles. AchE-acetylchoolinesterase breaks down the remaining ACh.
1) there’s exchaustion of Ach from vesicles
2) breakdown of Ach with AchE
–> weaker with sustained contraction fatiguability
What does dystrophin do?
Stabilises the sarcolemma by anchoring it tot he actin and ECM
What happens in DMD?
1) Dystrophin not tethered to the sarcolemma
2) When muscle contracts sarcolemma more vulnerable to shear forces, and tiny rips appear
Why do we see a single image when we have 2 eyes
binocular vision to preserve depth
Why do we see double?
1) Misalignment of the eyes (Strabismus)
2) Lens or cornea issues
3) Nerve or muscle damage
4) Fatigue or alcohol
Why do you have nasal speech?
If the soft palate is weak and fails to elevate or occlude the nasal passage, air goes through the mouth and the nose.
What happens when you speak?
Soft palate is elevated to occlude the nasal passage, allowing air and sound to come out exclusively through the mouth
What happens when you swallow?
Palaete goes up, epiglottis comes down to protect the airway
Why do you choke?
1) Epiglottis fails to protect the tracheal entrance causing water to go the wrong way
2) Soft palate fails to elevate fully, failing to occlude the nasal passage as one swallows
What is TTX?
Tetrodotoxin is a potent neurotoxin, which a powerful blocker of voltage gated sodium channels, which stops nerves conducting. You get tingling and weakness. Although CNS nerves are sensitive, TTX does not cross blood brain barrier.
Symptoms of Myastenia Gravis
1) dysphagia
2) ptosis
3) hypophonia
4) proximal muscle weakness
basically skeletal muscle weakness
NOT BRADYCARDIA
