neuromuscular junction muscle contraction and normal muscle tone Flashcards
absolute refractory period
depolarization
repolarization
refractory period
a time during which an organ or cell is incapable of repeating a particular action
relative refractory period
hyperpolarization
twitch
a single rapid contraction and relaxation of muscle fiber or group of muscle fibers
how many motor unit innervate a single muscle fiber
one
latent period
excitation-contraction-coupling
when does latent period begins
begins when action-potential cause depolarization in myocyte membrane
muscle tone
resistance felt by examiner
it is a partial state of contraction of a skeletal muscle to maintain its optimal length during resting
hypertonia
spasticity
rigidity
spasm
hypotonia
sloppy mushy feeling
classification of muscle tone
postural
phasic
muscle tone is regulated by;
spinal mechanism
supraspinal mechanism
spinal mechanism/control
- interaction between muscle spindle and spinal cord
- interneurons
supraspinal control
- via descending long tracts
- role of cerebellum
descending long traits
Inhibitory tracts -corticospinal and corticoreticular
Facilitatory tract - vestibulospinal and medial reticulospinal
what is the role of cerebellum in supraspinal control
activation of medullary reticular formation
hypertonic
spasticity
dystonia
rigidity
hyperkinetic
chorea
dystonia
athetosis
myoclonus
tremor
tics
stereotypies
neural factors of spasticity mechanism
-disruption of balance between inhibition or excitation in cns
- decreased excitability threshold of alpha motor neuron
- increase spontaneous discharge in gamma motor neurons
- disruption of reciprocal and autogenic inhibition controlling by interneurons
non neural factors of spasticity mechanism
viscoelastic properties changes
replaced sarcomere with fats
accumulation of titin
why spasticity occurs
it occurs as a result of diffuse or localized pathologies of cerebral cortex, brainstem or spinal cord
