Reflex arcs - week 23 Flashcards
Describe the components of a simple reflex arc
Sensory afferent neuron
Interneuron
Preganglionic fibre
Autonomic ganglion
Postganglionic fibre
What are muscle spindles?
proprioceptors that detect change in muscle length
What is the relationship of muscle spindles with gamma motor neurons?
peripheral parts of muscle spindle innervated by GMN
when GMN activate the muscle spindles will contract
What are golgi tendon organs?
receptors in ligaments/tendons
proprioceptors that detect change in muscle length
What do alpha motor neurons do?
sends signal causing stretched muscle to contract
What are the two types of muscle fibres?
Extrafusal and intrafusal
Describe extra and intrafusal muscle types?
Extra - on outside, innverated by LMN, attched to bone with tendon
Intra - on inside, has muscle spindles and contains actin and myosin
Two examples of reflexes?
Golgi tendon reflex
knee jerk/stretch reflex
What are descending pathways?
Motor pathways to allow muscles to contract
Where do descending pathways orginate?
cerebral cortex or brainstem
What do descending pathways contain?
Upper and lower motor neurons
Name the 5 descending spinal tracts?
Corticospinal
Reticulospinal
Reubrospinal
Vestibulospinal
Tectospinal
What do upper motor neurons do?
transmit motor commands from brain to spinal cord
What do lower motor neurons do?
innervate muscles
which tract is the only one that doesn’t originate from the brainstem
corticospinal
