Nervous System Lab Make up Reflexes, Sensory Receptors, and Reaction Time Purpose: To explore the body s reflexes, sensory receptors and reaction times and relate the findings to our study of the nervous system. This make up you will need the below materials most will have these at home, but if not I will check them out to you. Then answer all questions to receive full credit Materials: Reflex Hammer (use side of hand) 2 tooth picks Ruler Large index card with dot and X Deck of cards Reflexes Reflex actions in a human usually require at least three neurons; a sensory neuron, interneuron and a motor neuron. One exception to this rule is the knee-jerk or patellar reflex it only uses the sensory neuron and motor neuron. Working in your group, each member should serve as the subject to complete the following reflex labs. A. Patellar reflex. a. The subject should sit on the edge of a table and have their leg hang freely. b. Locate the patella (knee cap) and the tendon below it. c. A different lab partner should sharply strike the tendon with the reflex hammer d. If done properly it should result in a kicking motion. Motor reinforcement of the patellar reflex e. Repeat the above procedure f. Have the subject interlock his or her fingers and attempt to pull them apart as vigorously as possible just as the blow is struck. Observations (describe the response of the subject when the tendon is hit) 1. Is the subject in control of the kicking motion? (why or why not) 2. What section of the nervous system (specifically) is the reflex part of? 3. What effect does the muscular tension (interlocking of fingers) have on the reflex action? 4. Explain how clenching your fists during a fight or athletic contest may affect your reflex response.
B. Pupil reflex a. Go to the edge of the lab where the light bulbs are placed b. Close one eye and cover it with your hand, keep the other eye open c. Stand facing the light so that the light shines near your open eye CAUTION: do not shine light directly into the eye d. Have your lab partner position themselves so that they will be able to see both of your eyes e. Quickly remove your hand and open your closed eye f. Observe what happens to the pupils of both the eye exposed to light and the eye that remained in darkness. Record the observation in the data table Stimulus Light Dark Observations 5. What happened when one eye was exposed to light and the other was covered? D. Achilles Reflex g. Subject should kneel on one knee on a chair while standing with your other foot on the floor. h. Lab partner should tap the Achilles tendon just above the heel with a reflex hammer. Record your observations below. Observation 6. Using page 904 draw and label a diagram of a reflex from figure 35-11
Sensory Receptor There are five main sensory receptors on the human body: mechano, photo, chemo, pain, and thermo. All five use the same action potential impulse to send the message to the brain, just different parts of the brain are notified. For example, vision from photo receptors go to one section of the brain, while mechanoreceptors for touch go to another section of the brain. E. Touch- sensitive areas of the forearm and fingertips (mechanoreceptors) a. Have the subject close his or her eyes and turn their head away. b. The lab partner should use 2 tooth picks and touch them together on the subjects forearm at the same location. c. Have the subject say how many pokes he or she feels. d. Take the tooth picks off of the forearm and repeat with the tooth picks slights apart. e. Repeat until the subject feels two pokes. Measure this distance and record in the data table. f. Repeat the experiment, but use the finger tip instead of the forearm. Touch area Forearm Finger tip Observation (record in mm the distance between the two tooth picks 1. Why does the person only feel one tooth pick when they are placed extremely close? F. Blind spot (photoreceptors) The blind spot is the area in the eye that lacks rods and cones. It is where the retinal artery comes out of the back of the eye. Because of the lack of photoreceptors when an image hits that area of the retina a signal is not sent to the brain, thus we do not see it. a. Using the large index card with a circle and a plus sign. b. Cover you left eye
c. Bring the card up to your face with the plus sign right in front of your right eye d. Lower the card a few centimeters e. While focusing on the plus sign began pulling the card away from your face until the circle disappears f. Measure and record the distance of the card from your face. Observations 3. Measure how far the card is from your face. Record this measurement here. 4. Draw and label a diagram of your eye using page 907 of your book Reaction times H. Ruler reaction time Procedure 1- Partner 1, rest your right elbow on the edge of the lab bench, so that your forearm is hanging over the edge. 2- Partner 2, hold the end of the ruler between your forefingers and thumb at the 30cm mark. 3- Partner 1, place the opposite end of the ruler between your forefingers and thumb, you are not to be holding it. The ruler should be dangling between your fingers. 4- Both partners need to look at the ruler. 5- In trials 1 and 2, partner 1 will count to 3 then drop the ruler. Record the distance the ruler dropped in Data table 1. This will be the number where partner 1 s thumb and forefingers land on the ruler. 6- Repeat this for all lab members. 7- In trials 3-4, partner 1 will no longer count before dropping the ruler. Partner 1 will drop the ruler at random times and partner 2 will catch the ruler and record the number where the forefinger and the thumb land in data table 2. 8- Repeat this procedure until data table 2 is filled up (trials 3-4).
9- Now switch roles and repeat the steps above. Data Table One Data Table Two Trial Number Recorded (cm) Trial Number Recorded (cm) 1 3 2 4 1 3 2 4 1 3 2 4 Questions 1- Which trials had a faster response time (with the count or with out), Why? 2- What are some other examples of reflex responses? 3- When multitasking what happens to your reflex response? 4- What effect do drugs have on reflexes? 5- What effect do synapses have on the response? I. Card Reflex (Use cell phone stop watch for this activity) Procedure 1- Partner 1 will pick up the deck of card, while partner 2 will obtain a stop watch. 2- Partner 1 will then deal the cards one-by-one into a pile while partner 2 records the time it took on the stop watch. Record this information in Data table 3. 3- Partner 1 will now deal the cards into to piles, RED and BLACK. While partner 1 is dealing the cards partner 2 will record the time it took to deal the cards on the stop watch. When done record the information in Data table 3. Data Table 3 Trials First Deal Second Deal (Red/Black Separation) Third Deal (Suit Separation) Time (in seconds)
4- Subtract Fist Deals time from Second Deals time. seconds. This is the period of time which measures the effect of the neural process involved in discrimination. 5- Now shuffle the deck of cards thoroughly. 6- Partner 1 will now deal the cards into 4 piles depending on their suit. Partner 2 will record the time it took on the stop watch. Record this time in Data table 3 under 3 rd deal. 7- Repeat this process for each lab member to see who can process color and suit the quickest. Data Table 4 Suit Separation Trails 1 2 3 Time (in seconds) Questions 1- Compare the times in trials 1-5 in data table 4. 2- When separating the deck into suits, did the dealer always put the card piles in the same order? 3- In data table 4 is there evidence of training? 4- What does the card deal tell us about reaction time and reflexes?