Physiology: Nervous System and Reflex

Topics: Nervous system, Eye, Sensory system Pages: 9 (1899 words) Published: April 21, 2014

Reflex and Sensory Physiology. Lab # 4
Satta Charis Bemah
Wilmington University

Reflex and Sensory Physiology

What is the purpose of this exercise?
The purpose of this lab is focus towards testing our reflexes and sensory physiology. We use these every day but we rarely do understand how much they contribute to our ability to function normally. A reflex is a rapid, involuntary motor response to stimuli. We will be conducting several experiments to test our reflexes throughout this lab.

Are there any safety concerns associated with this exercise? If so, list what they are and what precautions should be taken. Some of the safety precautions include: wearing safety glasses, mask, and gloves. We need to also be careful with sharp objects which are involved. Keep all lab materials out of reach of children.

Exercise 1: Stretch Reflexes


A. Which muscles contracted with the patellar reflex?
The muscles contracted with the patella reflex include the sharp top on the tendon which slightly stretches the quadriceps, the complex of muscles which is at the front of the upper leg. These muscles in reaction, contract and the contraction tends to straighten the leg in a kicking motion.

B. Which nerves carried the stimulus to the spinal cord?
The nerves which carried the stimulus to the spinal cord stimulates stretch sensory receptors that trigger an afferent impulse in a sensory nerve fiber of the femoral nerve leading to the lumber region of the spinal cord.

C. Is the patellar reflex response during mental distraction greater than or less than the response without mental distraction?

The knee jerk may be reinforced by a second stimulus, such as a loud noise when the noise is appropriately timed with respect to the tapping of the tendon.

D. What can be concluded about the effect of mental distraction on reflex activity?

I would conclude a decrease in mental excitement is associated with a decrease in the reflex.

E. Is the patellar reflex more or less vigorous after exercise?

The strength of the tap required to evoke the reflex is higher after physical or mental work.

F. Did muscle function or nervous system activity cause the changes observed after exercise? Explain. For the fact that due to nervous system response and muscle fatigue, there is a decrease in response speed. This is because the human body needs time and rest in order to recover after exercise.

G. Describe the result of the Achilles tendon test.

The result of the Achilles tendon test is that it squeezes the calf muscles while watching for a flex response that is called plantar flexion, in the foot. The foot would move when the calf muscles are squeezed.

H. Does the gastrocnemius muscle normally do what you observed with this test? (Think about the function of this muscle). I observed that the gastrocnemius heads arises from the posterior portions of the femoral condyles. The gastrocnemius muscle is stretched with the knee fully extended and the soleus is the only stretched with the knee flexed.

Exercise 2: The Crossed Extensor Reflex


A. What happened when you pricked the subject’s finger?

When you picked the subject’s finger, the reflex occur the flexors in the withdrawing hands contract and the extensors relax, while in the opposite occurs.

B. Did this reflex seem to be slower than the other reflexes observed? Why or why not?

The reflex is slower because the signals need to travel up to the spinal cord and cause contraction of the contralateral muscles.

Exercise 3: Cranial Nerve Reflexes


A. Describe what happened when the subject’s cornea was touched. When the subject cornea was touched, you blink.

B. What is the function of the corneal reflex?

The function of the corneal reflex is involuntary movement of the eyelids through light, stimulation or...
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