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Reflexes: Muscle and Reflex Reinforcement

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    Contraction of Quadriceps Muscle and Extension of Leg Abstract1 The purpose of the Patellar reflex lab was to observe the effect of central nervous system influence on reflex amplitude. My hypothesis was a reflex with reinforcement would have a greater Max of (mV). In this lab we attached three electrode tabs to the leg and connected them to a EKG Sensor. Next we swung a reflex hammer in contact with the patellar tendon and observed the results without reinforcement and then with reinforcement. Our results showed that the reflex reinforcement had the highest results over without reinforcement.

    In conclusion our results showed that focusing on the hammer swing created a lesser reflex, while focusing on another part of the body allowed for a greater reflex. Introduction In purpose of this lab was to observe the effect of central nervous system influence on reflex amplitude, associate muscle activity with involuntary activation, and obtain graphical representation of electrical activity of a muscle activated by a reflex arc through nerves and form the spinal cord. My hypothesis for this lab was the mV maximum would be with reinforcement.

    My rationale for my hypothesis was when arms are clenched there will be an increased muscle tone in the rest of your body, therefore on your muscle spindle. The muscle muscle fibers will contract even more due to the spindle fibers already being experienced. When without reinforcement the body anticipated the tap therefore muscle spindle causes the muscle to contract to place resistance from over stretching. A reflex is an automatic response coordinated within the spinal cord through interconnected sensory neurons, motor neurons, and internuerons.

    A reflex is a single reflex beginning with a receptor ending at a peripheral effector generally opposes original stimulus. A patellar reflex results from tapping the patellar tendon below the knee with a reflex hammer. This causes contraction of the quadriceps muscle and extension of the leg. Stretching of the muscle activated nerve impulses (sensory acceptors) which travel to the spinal cord (sensory neurons) where motor neurons travel the impulses to the effector which results in muscle contraction. This is an xample of a reflex arch, which is influenced by other pathways to and from the brain. After a spinal cord injury information is gathered through reflexes to determine the severity of the injury. Spinal shocks are used to see how far up or down on the spinal cord injuries have occurred. The returning spinal cord reflex arcs below the level of injury are irrevocably altered and are the substrate on which rehabilitation efforts are based. This is important to know if nerves have been damaged in the body and ultimately determine if a person is paralyzed. Materials and Methods

    Materials include a computer, Vernier computer inferface,Vernier EKG Sensor, Logger Pro, electrode tabs, Reflex hammer and Pen 1. Connect the EKG Sensor to the Vernier computer interface. 2. Open the file “14B Reflexes without ACC” from the Human Physiology with Vernier folder. 3. Have the subject sit comfortably in a chair that is high enough to allow his/her legs to dangle freely above the floor. 4. Attach two electrode tabs above one knee along the line of the quadriceps muscle between the knee and the hip. The tabs should be 5 and 13 cm, from the middle of the patella.

    A third electrode tab should be placed on the lower leg. 5. Locate the subject’s patellar tendon by feeling for the narrow band of tissue that connects the lower aspect of the patella to the tibia. Place a pen mark in the center of the tendon, which can be identified by its softness compared with the bones above and below. 6. Attach the red and green leads to the electrode tabs above the knee with the red electrode closest to the knee. Attach the black lead (ground) to the electrode tab on the lower leg. 7. Click ? to begin data collection.

    If your graph has a stable baseline as shown in Figure 4, click ? and continue to Step 8. If your graph has an unstable baseline, click ? and repeat data collection until you have obtained a stable baseline for 5 s. 8. Collect patellar reflex data without and with reinforcement. Note: Read this entire step before collecting data to familiarize yourself with the process. Have the subject close his/her eyes, or avert them from the screen. Click ?. After recording a stable baseline for 5 s, swing the reflex hammer briskly to contact the mark on the subject’s tendon.

    If this does not result in a visible reflex, aim toward other areas of the tendon until the reflex is obtained. After 5 or 6 successful reflexes have been obtained, have the subject reinforce the reflex by hooking together his/her flexed fingers and pulling apart at chest level, with elbows extending outward. Continue obtaining reflexes until data collection is completed at 30 s. A total of 10–15 reflexes should appear on the graph. 9. Determine the average amplitude of the reinforced and unreinforced reflexes. Click the Statistics button, ?.

    Move the brackets to frame the first area of increased amplitude (depolarization) in this run . Record the minimum, maximum and ? y value (amplitude) for this depolarization in Table 1, rounding to the nearest 0. 01 mV. Close the Statistics box by clicking on the ? in the corner of the box. Repeat this process for 5 unreinforced and 5 reinforced depolarization events. Ignore rebound responses. Record the appropriate values in Table 1. Determine the average amplitude of the reinforced and unreinforced depolarization events Results Table 1 Reflex without reinforcementReflex with reinforcement

    Reflex response Max(mV)Min (mV)Reflex response Max(mV)Min (mV) 11. 490. 8711. 780. 77 21. 20. 9521. 460. 87 31. 10. 9831. 440. 87 41. 130. 9741. 70. 81 51. 150. 9551. 580. 81 average1. 2140. 944average1. 5920. 826 Table one shows that reflex with reinforcement has the maximum mV and reflex without reinforcement had the lowest maximum. In addition reflexes were larger at reflex one than at reflex 5 in each of the tables. Table 2 ? In table two the graph shows that the neuromuscular reflex without reinforcement has a lower potential in mV.

    In addition the reflex with reinforcement has a higher potential mV. Discussion The goal of this experiment was to understand the effect of a reflex with and without reinforcement. My results showed that a reflex with reinforcement had a higher potential in mV than reflex without reinforcement. This is because an increase in muscle tone( of the arm) increases extent of knee jerk. Subject is not focusing on knee tap. With no reinforcement the body anticipates muscle is about to be overstretched therefore spindle fibers cause the muscle to contract to place resistance from over stretching.

    This was expected because thinking about my knee being tapped made me contract my leg before the experiment. My hypothesis was correct reflex with reinforcement was greater than a reflex without reinforcement. Conclusion The purpose of this lab was to observe the effect of central nervous system influence on reflex amplitude, associate muscle activity with involuntary activation, and obtain graphical representation of electrical activity of a muscle activated by a reflex arc through nerves and form the spinal cord.

    In summary a reflex with reinforcement had a greater mV potential than a reflex without reinforcement, which was my hypothesis. This lab taught me a spinal arc, and how reflexes react with anticipation and reinforcement.

    References 1. Atkinson, P. , & Atkinson, J. (April, 1996 7). Spinal shock. Retrieved from http://www. ncbi. nlm. nih. gov/pubmed/8637263 2. MSC Web Designs. (n. d. ). Testing reflexes redefining spinal shock. Retrieved from http://www. streetsie. com/testing-reflexes-redefining-spinal-shock/ 3. Sarikas, S. (2009). Anatomy and physiology. (Second ed. ). San Fransisco: Pearson Learning Solutions.

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