Lab 3

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Austin Peay State University *

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4161

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Biology

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Apr 3, 2024

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Biology 4161: Human Physiology Laboratory Laboratory 3: Reaction Time & Reflexes NOTE: Do not consume caffeine within 6 hours of this laboratory! Introduction Today, we will perform two experiments. First, each group will design, perform, and analyze an experiment to study reaction time. Second, each group will examine the dive reflex. Part 1 : Reaction Time A. Reaction Time 1. You will need a ruler to perform this experiment. 2. Have your subject sit in a chair while another student, the releaser, stands facing the subject. 3. The releaser should hold the top of the ruler between his/her thumb and index finger. The subject should hold his/her thumb and index finger 1 inch apart at the 0 mark of the ruler. 4. When the subject is ready, the releaser will release the ruler. The subject will try to catch the ruler as quickly as possible. Note: the releaser should be careful not to give any clues that might hint when he/she will drop the ruler. 5. Record the distance that the ruler fell before it was caught. 6. Perform this experiment 10 times for each person in the lab group. 7. Calculate the reaction times for each attempt using the following equation: t = square root (2 * y / g) Where: t = time (seconds) y = distance (cm) g = 980 cm/sec 2 (acceleration due to gravity) 1. Record the reaction time (in milliseconds) in the data table located in the lab assignment. 2. Calculate the average reaction time of each subject and record it in the data table. 3. Calculate the standard deviation for each subject and record it in the data table. Where: N = number of students X i = average reaction time for each student X bar = Group mean (constant for all students in group) 1. Calculate the average reaction time of each repetition and record it in the data table. A. Altering Reaction Time 1. Think of something that might alter the reaction time. 2. Formulate a hypothesis and a test based up your idea. 3. Perform the “ruler drop” experiment, incorporating your test. 4. Determine the standard deviation of the control and test group data using the formula above. Part 2 : Reflexes NOTE: Do not consume caffeine within 6 hours of this laboratory! Introduction These experiments will introduce you to the topic of reflexes. A reflex is an automatic, patterned response to a specific stimulus. Reflexes can be classified based upon a number of conditions. Spinal and cranial reflexes are those that are processed in the spinal cord or the brain, respectively. Somatic reflexes activate skeletal muscle, while autonomic reflexes control glands as well as smooth and cardiac muscle. A monosynaptic reflex contains only one synapse, while a polysynaptic reflex involves at least

two synapses. Lastly, innate reflexes are those that you are born with and do not need to learn, while conditioned reflexes are those that you must learn. A good example of a conditioned reflex is the salivation of Pavlov’s dog. A reflex arc is a series of events that occur in response to a stimulus that produces a reflex. A reflex arc has five components: sensory receptor, afferent neuron, integration center, efferent neuron, and an effector. Tests of reflexes are used to determine if the components of a reflex arc remain intact and undamaged. We will examine several reflexes today. I will not tell you what the response is supposed to be, that will be up to you to determine through careful observation. Procedure We will begin by examining several stretch reflexes. You only need to have one subject do these tests. 1. Knee Jerk - tests the femoral nerve ● Have a subject sit with his/her legs hanging freely over the edge of the chair. ● Strike the patellar ligament and observe the resulting muscle contraction. The leg should kick out in this reflex. OBSERVATION/RESPONSE: Once the patellar ligament was hit with the reflex hammer, the leg kicked out. 1. Ankle Jerk - tests the medial popliteal nerve ● Have a subject stand on one leg alongside a chair, with the other leg bent at the knee and its shin resting on the seat of the chair. The foot should project over the edge of the chair. ● Strike the Achilles tendon at ankle level and observe the resulting muscle contraction. OBSERVATION/RESPONSE: Cause toes to curl slightly and foot to point 1. Biceps Brachii Jerk - tests the musculocutaneous nerve ● Have the subject rest an arm on the desk. ● Locate the tendon of the biceps brachii muscle in the antecubital (anterior elbow) region. ● Gently press the biceps brachii tendon with the thumb and strike the thumbnail with the mallet. ● Note the twitch in the biceps brachii muscle. Usually the contraction is too weak to produce any significant arm movement. OBSERVATION/RESPONSE: small contraction of muscle 1. Triceps Brachii Jerk - tests the radial nerve ● Have the Subject lay his or her chest on the lab desk so that the upper part of the arm is resting on the desk and the forearm is hanging over the edge of the desk. ● Strike the tendon of the triceps brachii on the posterior surface of the elbow. OBSERVATION/RESPONSE: the muscle contracting caused arm extension Now, we will examine other types of reflexes. 5. Pupillary Light – tests the occulomotor nerve ● Have a relaxed and calm subject sit in a chair. ● Shine a flashlight into one eye of the subject. OBSERVATION/RESPONSE: As soon as the light shined in the eyes, the pupils quickly decreased in size, almost to a pinpoint. 1. Dive Reflex The dive reflex is initiated by placing your head under cold water while holding your breath. The reflex alters heart rate. 1. Attach electrodes to the right wrist and both ankles. 2. Attach the white lead to the wrist electrode, the black lead the right ankle, and the red lead to the left ankle.

3. Start the BSL PRO program. DO NOT USE THE BSL LESSONS PROGRAM! 4. On the menu bar choose: File menu > Open > choose Files of type: Graph Template (*GTL) > File Name: DiveReflex.gtl (or H08) . 5. Fill one washbasin with room-temperature water and another with ice water. Record the temperatures. 6. Remember these guidelines while conducting the experiment. 1. The subject should not talk or laugh during any of the recording segments. 2. The subject should be relaxed in the position noted for each recording segment. 3. The subject should be as still as possible during the recording segment. The electrocardiograph is very sensitive to small changes in voltage caused by contraction of skeletal muscles, and the subject's arms and legs need to be relaxed so that the muscle (EMG) signal does not corrupt the ECG signal. 4. Start recording a few seconds before the subject gets wet to give the computer time to display the data. 5. Subject should remain immersed for 20-30 seconds -- the longer the better! 6. Conduct immersions in random order and do not advise the Subject of the water temperature before immersion . 7. Allow an equilibrium period of no less than 3 minutes between immersions. 7. While the subject is relaxing, push the “ start ” button on the lower right corner of the BSL window. Record the heart rate until you have 30 seconds of stable data. 8. Have the subject close his/her eyes, hold his/her breath and immerse his/her head in the water. Do not tell the subject the water temperature or show the basin to the subject! 9. Push the “ F9” key when the subjects head enters the water to insert a marker on the computer screen. 10. Record the heart rate as long as the subject can keep his/her head underwater. 11. Repeat the experiment so that you have 2 trials in each washbasin. 12. Analyze the data for the first subject. Select the BPM or heart rate window. Change the data type from p-p to mean (upper left part of menu). Click on the I-beam tool. Highlight the area to be analyzed with the cursor. Read the heart rate from the window located to the right of the mean. 13. After you analyze the data from the first person, click on new , then repeat the experiment for the next group member of your group. Record data for all group members. Biol 4161: Laboratory Report 3 Group Members: Sierra Tevis, Jessica Raybuck, Tristin Smith, Lyra Leflore Complete the following table. (dont forget to calculate time from distance recorded)

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Trial Subject’s Reaction Time 1 2 3 4 5 Average 1 0.143 0.181 0.212 0.202 0.185 2 0.127 0.127 0.186 0.136 0.144 3 0.143 0.111 0.197 0.149 0.15 4 0.119 0.101 0.169 0.156 0.136 5 0.149 0.111 0.202 0.111 0.143 6 0.09 0.101 0.163 0.119 0.117 7 0.111 0.119 0.202 0.207 0.159 8 0.163 0.111 0.163 0.196 0.158 9 0.143 0.119 0.197 0.202 0.165 10 0.186 0.136 0.163 0.230 0.179 Average 0.137 0.122 0.185 0.171 Standard Deviation 0.0085 0.016 0.016 0.0085 1. Did the reaction time improve with practice? Explain how your data supports your statement. ~ Yes, as more trials were completed, the number at which the ruler was caught decreased. For example, in Table 2 subject three continued with trials the cm where it was caught decreased. 2. What physiological processes occur between the ruler falling and the catching of the ruler? ~ When the ruler is dropped, the eye sends a message to the visual cortex which then sends a signal to the motor cortex resulting in you catching the ruler

Altering Reaction Time Complete the following table. Treatment standing with non dom hand Subject’s Reaction Time 1 2 3 4 5 Average Treatment Trial 1 0.197 0.207 0.235 0.143 0.196 2 0.136 0.181 0.09 0.128 0.134 3 0.186 0.181 0.23 0.163 0.19 4 0.197 0.243 0.202 0.207 0.212 5 0.149 0.217 0.064 0.149 0.145 6 0.230 0.212 0.169 0.143 0.189 7 0.191 0.078 0.156 0.169 0.149 8 0.202 0.221 0.111 0.175 0.177 9 0.197 0.243 0.149 0.186 0.194 10 0.197 0.207 0.101 0.212 0.179 Average 0.188 0.199 0.151 0.165 Standard Deviation 0.005 75 0.011 3 0.012 8 0.004 25 1. What was your hypothesis? a. Switching to our non-dominant hand while standing will slow down our reaction time compared to sitting and using our dominant hand.w 2. Explain the test of your hypothesis. a. The first set of data was collected while sitting with the dominant hand. Then to test the difference the subject was standing and used their non-dominant hand to catch the ruler. Both tests were repeated a total of ten times per test subject. 3. Record the average and standard deviation used to test your hypothesis. a. Control Group: dominant hand/ sitting b. Test Group: non-dominant/ standing 1. Does your experiment support your hypothesis? Yes, the data collected supports this hypothesis, hence we fail to reject it. 2. Why or why not? The numbers for the control group on average were lower than that of the experimental group’s average.

3. Using your own words, explain the standard deviation Standard deviation is a measure of the average distance between the values of data in the set and the mean. Based on our standard deviation we have a high or large standard deviation because there is greater variability in our data set. 4. Which muscle contracted during the knee jerk? The quadriceps femoris muscle is contracted during the knee-jerk 5. Classify the knee jerk reflex. Remember to use all 4 classifications. a. the knee jerk reflex is a monosynaptic, spinal, somatic reflex involving both afferent and efferent neurons, and innate. 6. What were the effects of the ankle jerk? It causes the toes to curl and the foot to become pointed. 7. If the biceps brachii produced a strong contraction, what action would occur at the elbow joint? a. When it contracts, it shortens and pulls on the radius bone of the forearm, causing the forearm to move toward the upper arm. 8. What were the effects of the triceps brachii jerk? a. The primary effect of the triceps brachii jerk is extension at the elbow joint. 9. What happens in response to the pupillary reflex? As soon as the light shined in the eyes, the pupils quickly decreased in size, almost to a pinpoint. 10. Classify the pupillary reflex. Remember to use all 4 classifications. a. The pupillary reflex is a type of autonomic, cranial, visceral, innate, polysynaptic, and consensual reflex. ** Temperature in Celsius ** 8. Complete the following table (use trials 3 and 4 if applicable). Subject Trial Water Temperature Initial Heart Rate Final Heart Rate Change in Heart Rate 1 1 10 82 63 19 2 29 82 38 44 3 29 79 20 59 4 10 75 52 23 2 1 28 78 66 12 2 12 70 53 17 3 12 72 73 +1 4 28 76 67 9 3 1 11 52 53 +1 2 11 50 64 +14 3 28 58 86 +28 4 28 53 59 +6 4 1 27 78 78 0 2 14 70 27 43

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3 14 64 56 8 4 27 82 46 36 1. Using Excel, make a scatterplot of your data. Include a trend line. Choose the correct independent and dependant variables for each axis to show how temperature affects heart rate. Staple the scatterplot to your report. 2. How does the dive reflex alter heart rate? The dive reflex slows the heart rate down 3. What are the physiological benefits of the dive reflex? a. The dive reflex is an adaptive response that allows mammals, including humans, to optimize their physiological functions during underwater immersion. It helps extend the duration of submersion by conserving oxygen, redistributing blood flow, and minimizing metabolic demands. While more pronounced in aquatic mammals, the dive reflex in humans demonstrates the body's ability to adapt to underwater environments.

Lab 3

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