stretch reflex

stretch reflex

yesterday,hanis asked me question regarding the reflex.sigh*she always make me think twice and i need to double check my understanding.

so,this entry is dedicated to hanis,ceewahhh=p

b4 we discuss in detail,we need to know that the muscle consist in extrafusal muscle and also he muscle spindle.the muscle spindle contain 2 chains,nuclear bag chain and also nuclear fiber chain.
this two chains are innervated by Ia and type II nerve fiber.(they are sensory)

the motor neuron for the intrafusal muslce is gamma efferent and for the extrafusal muscle is alpha motor neuron.

inverse stretch reflex

monosynaptic reflex

so bila ada strecthing of the extrafusal muscle(bila tapping the knee dalam knee jerk),muslce spindle will also stretch.So strecthing ni akan menyebabkan muslce spindle become slender.more slender,more firing rate of Ia and type II nerve.so this axon ni akan bawak impulse pegi dekat post horn of the spinal cord.bila sampai dekat spinal cord,this nerve akan ada 2 kerja.satu dia akan innervate directly to the motor neuron which is gamma efferent.so gamma efferent akan menyebabkan intrafusal muslce contraction.bila intrafusal muscle contract,extrafusal muscle pun akan ikut contract.satu lagi,the Ia nerve akan synapse dengan internuclei yang mana this akan synapse plak dengan nerve yang innervate antagonist muslce.so gamma efferent yang innervate that muslce akan menyebabkan relaxation.so sebabtu dalam knee jerk,agonist contract,antagonist relax=P

terlupa plak,selain Ia innervate dekat spinal cord,dia jugak akan hantar maklumat to the CNS,mainly to the medulla.kira macam nak check betul ke tak movement yang dia buat.kalau tak betul dia akan hantar motor neuron untuk innervate the alpha and gamma efferent untuk buat kerja yang sepatutnya.and also,kalau that muslce over contract,kalau tak kawal boleh fatigue muslce tu.so apa yang kita akan buat?dekat tendon,ada satu receptor,namanya golgi tendon.so kalau ada overstretch,golgi tendon akan hantar maklumat melalui Ib afferent.ini akan synapse dengan internuclei,yang mana akan inhibit agonist muslce,and cause contraction of antagonist muslce(so agonist akan relax,antagonist akan contract plak)

p/s:harap membantu pemahaman kita semua,kalau salah tolong cakap ye=p