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Final

final exam review - long answers


Department
Biological Sciences
Course Code
BIOC21H3
Professor
Stefan Rusyniak
Study Guide
Final

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Long Answer:
Part B:
A neuron along with the specific muscle fibers that it innervates is called a motor
unit.
A single neuron may innervate several to a hundred or more muscle fibers
The larger the motor unit – the more muscle fibers the neuron innervates
Muscles capable of sophisticated, micro movements have the smallest ratio
between muscle fibers and neuron and thus have small motor units
oSince we have developed more delicate and sophisticated movements in
our finger compared to our back, we can predict that the finger will have a
smaller motor unit then the back where the movements are larger and have
less micro movements – the movements are lagers in the back
Therefore neurons innervating the back will have large motor units
– where as those innervating the finger will have small motor units
Part A
Demdrtes reicieve motor information via electrical impulses
The impulses are carried through the perkaryon
Enters axon through axon hillock
The axons utilize salutatory conduction – to allow action potel to jum from node
of ranvier to node of ranvier
The single mylinated axon leaves the ventral horn
The schwann cells wrap themselves around the tellodendria - the basement
membrane of the schwann cells fuses with that of the sarcolema at the
neuromuscular junction
oHelping to create a isolated microecnviroment for the interaction of the
terminal bouton with the sarcolema
oThe terminal bouton sits within this neuromuscular junction
oThe muscle fiber is bent inward at the neuromuscular junction
oCreating a grove for the terminal bouton to sit in
oThere is 20-30nm space btw the two
Created by the junctional folds of the muscle fiber
The nerve impulse carried through the neuron into the tellodendria causes an
influx of calcium into the terminal bouton causes the fusion of synaptic AcH
vesicles with the membrane of the terminal bouton
This will cause the release of AcH into the synaptic cleft
ACh binds with ACh receptors found within the synaptic cleft
This triggers a localized plasma membrane depolarization
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