KIN 460 Lab KIN 460 Lab Write up Copy and paste this section into a new word document Answer the following questions based on the procedures performed for the corresponding sections above Export your answer document to a PDF and submit your individual report to the appropriate Turnitin link on Moodle by the Sunday following this lab session at 11 59pm 1 15 pts Graph your data as a dual y axis scatterplot straight lines without markers a Primary y axis hammer force kg You should have both and values b Secondary y axis EMG activity mV You should have both and values c x axis time Refer to the Figure Grading Criteria below to ensure you have appropriate graph elements included in your figure Copy and paste the graph below EMG Response of Rectus Femoris in response to Hammer Force 0 2 Figure 1 g k e c r o F r e m m a H 0 15 0 1 0 05 0 0 05 0 0 2 0 4 1 1 2 0 8 0 6 Time s Hammer Force kg EMG Response mV Description The hammer was tapped against the participants patellar tendon and the rectus femoris response was measured below The hammer force was also shown 2 5 pts What was the reflex time of the rectus femoris The reflex time of the rectus femoris was 0 021 seconds 3 10 pts Describe the muscle spindle s role in eliciting a motor response muscular contraction during a knee reflex arc Your answer should include information about During the knee reflex arc the tendon pulls the rectus femoris upon the hammer strike The muscle spindles can sense this stretching as muscle spindles are stretch receptors that can detect changes in muscle length of the rectus femoris They lay parallel to the rectus femoris muscles As the stretching occurs these muscle spindles send sensory neurons which are afferent to the dorsal root ganglion in the spinal cord Once in the spinal cord these sensory neurons then synapse with motor neurons to contract the 0 6 0 4 0 2 0 0 2 0 4 0 6 V m e s n o p s e R G M E KIN 460 Lab rectus femoris while also signaling interneurons to inhibit the motor neurons of the hamstrings The leg can then kick out with reciprocal inhibition smoothly without the hamstrings preventing it from kicking 4 10 pts In the knee jerk reflex your hamstrings are lengthened when your quadriceps contract and shorten Explain why hamstring lengthening does not produce a new monosynaptic stretch reflex Your answer should include The hamstring lengthening doesn t create another monosynaptic stretch reflex because the muscles are inhibited instead of stimulated The reciprocal inhibition allows the firing of the rectus femoris and also inhibits the hamstring flexor the opposing muscle through the interneuron The hamstrings are prevented from contracting allowing the rectus femoris to contract which allows for a kick 5 10 pts Describe a the functional role of the stretch reflex 5 pts b and provide an example excluding the knee jerk reflex of a situation in which the stretch reflex contributes to motor control 5 pts The role of the stretch reflex is so that the muscles respond in response to stimuli and maintain good posture and balance so that muscles and tendons do not experience too much strain For example if somebody is leaning too far to the side the muscle spindles are able to detect the stretching of the postural muscles and respond in a similar way in the knee jerk reaction to the muscles to stay upright These reflexes occur within the spinal cord so they are unconscious reflexes that can happen quickly They are not sent to the brain which is important so that we are more efficient and don t have to be constantly thinking about every action such as posture