* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Group Number 4 Nick Ha, Andrew Phan Physiology Lab 8: Muscle 1.1) 1.2) 2.1) Table 2.1 Increasing Clench Force Data Assigned Force Increment Peak SS25L/LA = # Kg SS56L = kgf/m^2 #1 5.00 Dominant arm Nondominant arm Force at Peak Integrated EMG (mV) Force at Peak Integrated EMG (mV) 5.021 kg 0.05173 mV-sec 9.820 0.08706 #2 10.00 8.236 0.06365 16.3466 0.13073 #3 20.00 13.152 0.11425 26.8433 0.1881 #4 30.00 24.167 0.20235 #5 35.00 31.693 0.26506 #6 #7 #8 2.2) 2.3) 2.4 3.1) First a motor neuron sends an action potential which leads to the release of neurotransmitters. The neurotransmitter then binds to receptors on the muscle cell, creating an action potential along the muscle cell and the release of calcium, which binds to troponin,causing the actin and myosin to form cross bridges that attach and pull the filament according to the sliding filament model granted ATP is present. Once ATP is no longer bound to the myosin, the cross bridges are no longer present, leading to the stopping of the contraction. 3.2) The motor neurons are responsible for the EEG signal. This is because the motor neurons receive neurotransmitters from the central nervous system, and their axon consequently depolarizes in order to activate the muscle fibers. This depolarization is what causes the spike in the EEG due to positive ions flowing into the axon. 3.3) The EMG signal increases due to motor unit recruitment. When there is more strain or force that the muscle needs to exert, the sensory data from the muscle creates additional feedback that the more force is needed, and more action potentials are generated to activate more motor units that would synergistically combine to lead to more force and larger electrical signal as more motor units undergo depolarization/ 3.4) Subject 1: The percent difference between the dominant arm and the nondominant arm was 5.98%. The dominant arm was significantly stronger than the nondominant. Subject 2: The percent difference between the dominant arm and the nondominant arm was 1.78%. Although the dominant arm was slightly stronger than the nondominant arm, the difference was negligible and cannot be used to conclude whether one arm is stronger than the other. 3.5) There is a slight positive correlation between the dominant forearm circumference in cm and the max force in kg. This is shown by an r-squared value of 0.3157. However, the r-squared value is still fairly low so not many conclusions can be drawn. 3.6) With two same sized forearm, surprisingly, the nondominant arm produced more force per fiber. This is because the dominant arm had a ratio of 119.4 kg/mV-sec and the nondominant arm had a ratio of 142.7 kg/mV-sec 3.7) The difference of the average time of fatigue between the dominant arm and non dominant arm is approximately 8.94 seconds. It should also be noted that for the non dominant arm, time to fatigue was sometimes greater than the time to fatigue for the dominant arm. This could possibly be due to the non dominant arm exerting a small max force. 3.8) There are no specific trends between time to fatigue and forearm diameter or max force because the r-squared values from graphs 2 (forearm diameter and time to fatigue) and 3 (Time to fatigue versus max force) both being too small to draw any proper conclusions.