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1b afferent fiber reflex
-attaches to golgi tendon organ to transfer sensation of muscle tension
-excites interneuron to excite antagonist muscle (to counteract the force causing the muscle stress)
-excites inhibitory interneuron to agonist muscles (on same side) so they relax and alleviate stress
gamma motor neurons in response to muscle stretch
they are activated in response to muscle shortening
-they cause intrafusil muscle fibers (that sense muscle stretch) to contract along with the muscle
-control the sensitivity of the muscle spindle fiber when they shorten
1a afferent fiber
sensory fiber that transfers sensations from the muscle spindle
-shortens in response to external forces pulling on muscle (ie when the hammer taps it pulls on the tendon, stretching the muscle)
-excites agonist muscles to contract, excites inhibitory interneuron to antagonist muscles (so they contract)
golgi tendon reflex
-involves the golgi tendon organs
-reverse of the stretch reflex
-agonist muscles relax and antagonist muscles contract
-why you might drop a load if it gets too heavy
-when tendons sense they are under tension, muscles act to alleviate that tension
stretch reflex -what is it? examples
-examples: flexing biceps to maintain glass being held at a certain level when beer is added to the glass, having reflexes tested at the doctor's office
-when a muscle senses it it stretched, muscles react to keep maintaining that muscle length
what is the effect of lower motor neuron damage on the stretch reflex?
-hyporeflexia, less response to stretch
-happens in response to damage to the Ia afferent fiber
what is the effect of upper motor neuron damage to the stretch reflex?
-hyperreflexia
how does upper motor neuron damage cause the effect they do on the stretch reflex?
-a lot of upper motor neuron control is inhibitory
-with less inhibitions, the gamma motor neuron is more active, and therefore the spindle fibers are more sensitive
-alpha motor neurons in spinal cord receive less inhibitory inputs, and are more sensitive to being triggered to contract
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