11/28: Neuromuscular Control Flashcards
What is the CNS dividded into?
Afferent and efferents
What are afferents?
Sensory neurons
to CNS (somatic and visceral)
What are efferents?
Motor neurons
Away from CNS (autonomic and somatic)
What do somatics innervate?
Skeletal muscle (motor neurons)
What is a motor unit?
Motor neuron and all the fibers it innervates
What acetylcholine receptor is found on skeletal muscle?
Acetylcholine nicotine
What does stimulation of the Ach nicotinic reecptor lead to?
Change in membrane potential - end plate potential
End plate potential usually always causes…
An action potential
What proteins are responsible for carrying the AP across a muscle?
Voltage gated sodium channels
What is an end plate potential?
The stimulation in membrane potential of skeletal muscle
Do end plate potentials almost always cause an AP to form?
Yes
Once a T-tubule brings an AP down into the muscle cell from the surface, what are the steps that occur in order for Ca+2 to actually be released?
- AP acts on Dihydro purine receptors (DHPRs)
- DHPRs change conformations and physically attach to RyR1 receptor
- RyR1 receptor acts on SR to release Ca+2 intramuscularly
What protein is responsible for allowing Ca+2 reuptake after contractions have ceased?
SERCA
Regarding actin and myosin, what protein is responsible for connecting the cytoskeeton of the fiber to the extracellular matrix?
Dystrophin
What complex does dystrophin attach to on the SR?
Dystrophin-associated protein complex
What is the syndrome called when one lacks the dystrophin protein?
Duchenne muscular dystrophy
What are the two products acetylcholine is broken down into by acetylcholinesterase?
Choline and acetic acid
What co-transporter is choline reabsorbed with?
Sodium-Choline co-transporter
What enzyme turns choline and acetyl-CoA back into acetylcholine?
Choline Acetyl transferase
What does SERCA stand for?
Sarcoplasmic
Endoplasmic
Reticulum
Calcium
ATPase
Once SERCA has reuptaked Ca+2 into the SR, what protein within the SR is responsible for maintaining the concentration gradient of Ca+2 so it is held within the SR?
Calsequestrin
Ultimately, Ca+2 will need to be released from the SR to go extracellularly, besides the
Ca+2 ATPase pump, what other pump is responsible for this?
NCX
How does NCX work?
By using the Na gradient to allow Na to come into muscle cell while pushing Ca out of it
What toxins inhibit Ca+2 channels within neurons?
Conotoxin
How does BoTox work?
BoTox works by inhibiting ACh release by inhibiting the snare proteins necessary for vesicle fusion
What compound prescribed inhibits acetylcholinesterase activity and INCREASES muscle contraction?
Physostigmine
If one wanted to INCREASE muscle contraction and activity, what compounds would you prescribe?
Acetylcholine
Nicotine
What compound inhibits acetylcholine nicotinin (AChR) receptors and DECREASES muscle contraction?
alpha-Tubocurarine (Curarine)
What inhibits ACh release and DECREASES muscle contraction?
Botulinum toxin (BoTox)
What inhibits neuronal Na+ channel and DECREASES muscle contraction?
Tetrodotoxin
What inhibits Ca2+ channel and DECREASES muscle contraction?
w-Conotoxin
What causes myasthenia gravis?
Autoimmune attack to the acetylcholine nicotinic receptors so ACh cannot bind
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