BIOS252 Lab report 2

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Chamberlain College of Nursing *

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252

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Mechanical Engineering

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Apr 3, 2024

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AP II - Week 2 Lab Instructions Neurophysiology Activity Deliverable Points All Lab Deliverables Reflexes and General Senses Lab Exercise and Questions 30 References: 1. Saladin Anatomy & Physiology: The Unity of Form and Function Complete Reflexes and General Senses Lab Exercise BACKGROUND: Nervous tissue cells are divided into two categories: 1. Neurons – cells that conduct electricity 2. Neuroglia – cells that do not conduct electricity but rather function in support of neurons. The nervous system has two major divisions: 1. Central Nervous System (CNS) – the brain and spinal cord 2. Peripheral Nervous System (PNS) – all nervous tissue outside of the CNS The PNS can be divided into: a. Sensory nerves – afferent nerves; nerves that convey sensory information from sensory receptors INTO the CNS b. Motor nerves – efferent nerves; nerves that convey motor impulses out of the CNS to the effector muscle or glandular cell A typical neuron has three parts:  Dendrites: the main receiving or input area  Cell body (soma): which includes the nucleus and other typical cell organelles  Axon: which is typically the output part of the cell that propagates nerve impulses toward another neuron, muscle fiber, or gland cell. (See image on the next page) BIOS252 Week 3 Lab Instructions (B) Page 1 of 9

Axons can be surrounded by an insulating layer of fat called the myelin sheath. The myelin not only functions to insulate the axon but to also speed up the electrical conduction of the neuron. At the end of the axon is the communication space between the neuron and the target cell called the synapse. The synapse is the site where a chemical called a neurotransmitter or an electrical current can be passed from the nerve the presynaptic cell (the nerve) to a postsynaptic cell (the target cell). BIOS252 Week 3 Lab Instructions (B) Page 2 of 9 Axon Dendrites Cell Body Neurotransmitter Synapse Postsynaptic cell Presynaptic cell

Reflexes involve a sensory receptor sending a signal up the sensory nerve to the spinal cord. The information is then integrated in the spinal cord when the signal is send from the sensory dorsal horn to the motor ventral horn. The signal will then be sent out the motor neuron to the effector cell. General Senses The two-point discrimination test. In this test you will be checking the sensitivity of two areas of skin to touch. Two-point threshold will be checked in this portion of the lab. This is the smallest distance apart that two objects can touch your skin and you perceive two different touches. Eventually, as the two touches become closer and closer together, your brain will register them as one touch. Thermoreception is the ability of the nervous system to detect a change in temperature. Free nerve endings are responsible for registering this sensation in the skin. Since these receptors are unequally distributed throughout the skin, you can use a small probe and find places on the skin that are unable to sense a change in temperature. You will use a small temperature probe, changing the temperature of the probe and testing for these distributions on the skin. You will also test for adaptation, the ability of the body to adjust to a particular sensation over time. OUTCOMES: In this lab, you will be asked to look at and describe the cellular and functional components of the nervous system. You will be able to explain how a reflex arc works. You will also be able to perform and interpret common clinical tests of the nervous system. This lab will be covering the following course outcome: CO2: Given an illustration of the nervous system, analyze its structure and function. MATERIALS:  Reflex Hammer  Aluminum temperature probe  Ink pad  Grid stamp  Monofilament BIOS252 Week 3 Lab Instructions (B) Page 3 of 9 Effector (Contraction of the muscle) Motor nerve Integration Sensory nerve Receptor

 Two-point discriminator  Thermometer  2 foam cups PREPARATION: 1. Read your lab in its entirety before coming to class. 2. Clear your workstation of all unnecessary materials. Book bags and or purses should be hung on hooks or places at the front of class. Make sure all other unnecessary materials (coats, drink containers, unused textbooks, etc.) are all stored and placed in a safe area out of the way. 3. Obtain all materials listed above. 4. Familiarize yourself with your lab materials. Make sure it is your water temperatures are prepped and ready at the correct temperature. 5. Be aware of the instructions for documenting your lab work. You will be performing the lab on yourself or one of your group partners. Make sure to select who will be performing the experiments, who will be the subject of the experiments, and who will record the results. 6. Fill one of the foam cups with ice water 10˚C (50˚F). Fill the second cup with hot water to between 30- 45˚C (86-113˚F) ACTIVITY: 1. Patellar Reflex - Have your designated group subject, sit in a chair with the legs crossed setting the right leg over top of the left leg. The experimenter will then locate the patella (kneecap) on the subject’s right knee. Using the reflex hammer, gently tap the patella tendon and observe the reflex (extension of the subject’s lower leg). Record your result. Repeat these steps with the subject’s left leg and record the results. 2. Achilles Reflex - Have your designated subject sit in a chair or on a bench with their legs freely suspended from the edge. Alternatively, the subject can kneel on the chair with their foot off the edge of the chair. Using the flat edge of the reflex hammer, gently tap the subject’s Achilles tendon and record the reflex. Have the subject switch to the other leg and repeat the steps recording your observations/results. You may need to place your hand under the plantar portion of the foot to feel the reflex as it is often hard to see. 3. Babinski Reflex - Have the subject extend their right foot to you while sitting in a chair. Using the handle side of the reflex hammer, start at the heal of bottom of their bare right foot and stroke the hammer up towards the toes and then over to toward the big toe in a “J” pattern. The expected result is an extension of the big toe. Record your results. Repeat these steps with the subject’s left foot and record the results. 4. Biceps Reflex – Have the subject sit in a chair with their right arm exposed. Place your thumb on the biceps tendon. Tap your thumb with the reflex hammer with enough force to elicit the reflex. Record your results. Repeat these steps with the left biceps and record the results. 5. Triceps Reflex – Have the subject sit in a chair with back of their right arm exposed. Hold the subject’s arm relaxed and bent. Locate the triceps tendon at the elbow. Tap the tendon with the reflex hammer with enough force to elicit the reflex. Record your results. Repeat these steps with the left biceps and record the results. 6. Stimulus Sensitivity Testing – Have the subject sit on a chair or bench and face the person performing the experiment. Using the grid stamp and ink, place a grid on the back of the test subject’s right hand, the palm of the subject’s right hand, and the inside of the subject’s right forearm. With the subject’s eyes closed, the experimenter will begin lightly touching each square of the grid with the medical monofilament and recording where they feel the stimulus in the corresponding grid in the Observations Report. Repeat these steps with the grids on the palm of the hand and the forearm and record those results in the appropriate grids in the Observation Report. BIOS252 Week 3 Lab Instructions (B) Page 4 of 9

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