3C - Lab report 3 part c PDF

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Lab report 3 part c...

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February 20, 2020 BIOL 5600 Section 5 Experiment 3: Possible Sites of First Fatigue, Axonal Conduction and the Neuromuscular Junction Section C: Effect of Lidocaine Table 3

Discussion

Continuous muscle contraction, often called tetanic contraction, is the effect of repetitive activations of muscle fibers and the summation of responses successive stimuli that aid animals in lifting heavy objects that would not normally be possible with a single muscle stimulation (Celichowski, 2019). However, if a muscle is stimulated to continuously contract it will eventually lead to a point of fatigue where muscle force steadily begins to decline with repeated stimulations (Person, 2006). The focus of this lab was to observe fatigue in muscles and how drugs such as lidocaine affect the rate of fatigue. Lidocaine is a local anesthetic that stabilizes the lipid bilayer of neuronal cell membrane and makes it less flexible and more resilient to change (Person, 2006). This causes ion channels such as the voltage-gated sodium channel in the neuronal membrane and in the conduction system in cardiac muscle from changing shape and allowing action potentials to propagate along the membrane which decreases impulse generation and strength of muscle contractions (Person, 2006). In skeletal muscle, lidocaine addition directly to the muscle does not affect the strength of contraction when being innervated by a neuron. When lidocaine was added to the sciatic nerve of a frog and then stimulated multiple times, the force of contraction of the gastrocnemius muscle decreased from 40.06 grams to 29.40 grams. This result shows how lidocaine application to neurons causes a decrease in action potential propagation which results in a decrease in muscle contraction. However, when the gastrocnemius muscle was innervated directly and not through the neuron, the contraction force increase to 35.82 grams. This value was slightly lower than the control muscle contraction value, possibly due to imprecise placement or movement of the pin electrodes in the gastrocnemius muscle. Lidocaine addition directly to the muscle should not affect muscle contraction due to action potentials being able to propagate normally within the neuron that innervate the muscle.

Journal

Teague Kelly BIOL 5600 Section 5 February 20, 2020 Experiment 3: Possible Sites of First Fatigue, Axonal Conduction and the Neuromuscular Junction Stimulus: Single stimulus at 2.1 volts with 10 second intervals between each muscle (M) and nerve (N) control stimulation and 20 second intervals between each lidocaine affected nerve (LN) and muscle (LM) stimulation. Sensing Device: Myograph

Control

Lidocaine Nerve Contractions

Lidocaine Muscle Contractions

Voltage: 2.1V

Voltage: 2.1V

Voltage: 2.1V

N1 – 38.63g

LN1 – 37.86g

LM1 – 35.47g

N2 – 40.06g

LN2 – 37.79g

LM2 – 35.51g

M1 – 43.64g

LN3 – 36.64g

LM3 – 35.82g

M2 – 43.23g

LN4 – 36.66g LN5 – 34.46g LN6 – 35.32g LN7 – 35.58g LN8 – 34.53g LN9 – 35.51g LN10 – 32.01g LN11 – 30.42g LN12 – 29.96g LN13 – 29.40g LN14 – 29.92g LN15 – 31.62g

C – Nerve and muscle control contraction (N1, N2, M1, M2), effect of lidocaine on nervous stimulation of the muscle (LN1 – LN15) and effect of lidocaine on direct muscle stimulation (LM1 – LM3).

Citations Celichowski, J., & Krutki, P. (2018). Chapter 4 - Motor Units and Muscle Receptors. In Muscle and Exercise Physiology (1st ed., pp. 51–91). London, United Kingdom: Academic Press, an imprint of Elsevier. Person, D. J., Ward, C. K., & Henry, R. P. (2006). Student Animal and Mammalian Physiology Handbook for the Biopac System (3rd ed.). Dubuque, IA: Kendall Hunt....