Virtual lab 9 Activity 2: Determining the Latent Period 1. How long is the latent period? 2.78 msec. 2. What occurs in the muscle during this apparent lack of activity? Ca++ is being released from the sacroplasmic reticulum and filament movement is taking up slack. Activity 3: Investigating Graded Muscle Response to Increased Stimulus Intensity 1. Use your graph to answer and note that the dot in the graph turns red when you select that line in the table. What is the minimal, or threshold, stimulus? 0V. 2. What is the maximal stimulus? 10V. 3. How can you explain the increase in force that you observe? the increase is how many volts went into the muscle. Activity 4: Investigating Treppe 1. What happens to force …show more content…
Activity 7: Investigating Muscle Fatigue 1. Why does the force begin to decrease with time? Note that a decrease in force indicates muscle fatigue. Because there is not enough ATP being produced to allow the muscle to contract that many times and for the length of time. 2. The muscle will produce force for a longer period if the stimulator is briefly turned off than if the stimulations were allowed to continue without interruption. Explain why. Because for the brief time that the stimulation is off the muscle can produce more ATP to supply the contractions with. 3. Describe the difference between the current tracing and the myogram generated in step 6. The current tracing does not dip as much but gradually decreases as the muscle fatigues. Activity 8: Investigating Isometric Contraction 1. What happens to the passive force as the muscle length is increased from 50mm to 100mm? The passive force increases. 2. What happens to the active force as the muscle length is increased from 50mm to 100mm? The active force increases until 74-76 then starts to decrease again. 3. What happens to the total force as the muscle length is increased from 50mm to 100 mm? It does the same thing as the active force does except for in increases at the end again. 4. Explain the dip in the total
Oxygen debt in the muscles is reached when oxygen levels are much lower than required during strenuous physical activity, causing lactate fermentation to occur in the cells leading to muscle fatigue. The results found in the experiment were the number of squeezes in the first trial for the dominant and non-dominant hands were significantly higher than the remaining ones. The results also showed as the trials continued, the number of muscle contractions decreased steadily which supported the hypothesis. However, there were some increased numbers for the dominant hand from trial 4 to 5 and trial 9 to 10. The non-dominant hand expressed similar unexpected results from trial 6 to 7 and trial 9 and 10. The reasons for these results might be due to the finger muscles being worked at the high intensity for a long period of time causing the muscles to consume higher amounts of oxygen thus producing more ATP production. This would cause the muscles to create more contractions towards the end of the trials. The unexpected results could also be caused by experimental errors such as faulty clothespins. The springs connecting the two ends of the clothespin was tight causing the number of contractions as the trials progressed having a more significant decrease. This is because the amount of energy required to open and close the clothespin would be higher, causing the lactate threshold to occur quicker. Due to this, the number of squeezes would decrease drastically as the trials progressed, in contrast to if the springs were normal. This would change the results by the difference between the trials not being evident therefore, not demonstrating the effects of muscle fatigue. Another factor that altered this experiment was the participant’s condition, Palmar Hyperhidrosis –excessive sweating on the palms – which
The more stimuli per second, the greater the force generated by the muscle due to a
This activity is the critical driving force of muscle contraction. The stream of action potentials along the muscle fiber surface is terminated as Acetylcholine at the neuromuscular junction is broken down by acetyl cholinesterase. The release of Calcium ions is ceased. The action of the myosin molecule heads is obstructed because of the change in the configuration of troponin and tropomyosin due to the absence of calcium ions. This will eventually cause the contraction to be ceased. Together with these physical processes, an external stretching force such as gravity pulls the muscle back to its normal length.
5. Now take each stage in turn and discuss how sustained neural activity could create a dysfunction and result in a decrease in muscle response during repetitive motor nerve stimulation.
1. Predict if healthy muscle or muscle with MH will contract with the most force.
#2. What changes in Jim's muscles promote unloading of O2 from hemoglobin for use by the muscles cells?
than they would at their natural length. This means that the muscle fibers will generate less tension with each
Smooth muscle contraction occurs when calcium is present in the smooth muscle cell and binds onto calmodulin to activate myosin light chain kinase (Wilson et al., 2002). Phosphorylation of myosin light chains result in myosin ATPase activity thus cross-bridge cycling occurs causing the muscle to contract (Horowitz et al., 1996). There are two known models of excitation and contraction in smooth muscle, electromechanical coupling (EMC) and pharmomechanical coupling
As a result of the contractions in the Muscle- Skeletal Longitudinal Section cells and the Muscle- Skeletal Cross Section cells, it allows your muscle to be able to contract in response to nerve stimuli. This means that the movements of most of these muscles are not involuntary, you can control them. Therefore, once the stimulation stops, the muscles relax.
Introduction: According to the “Human Physiology Laboratory Manual “,BIOL 282 ,page 31 , the reason of performing this experiment is to learn how the muscle contraction occurs based on the molecular level and what kind of factors are involved .As a matter of fact, skeletal muscles contain a lot of nuclei because of the cell fusion while being developed and are made of cylindrical cells that have myofibrils. The myofibrils contain sarcomeres and the
15. Name and describe the four functional abilities of muscle that are the basis for muscle response.
1. How is there a lower metabolic cost but with the higher forces during eccentric contraction?
The Purpose of this exercise is to understand how muscle twitch, contract and react to different activities.
9. Strong involuntary muscle reactions to shocks can occur in a amperage ranges as low as __________________.
This is because once a contraction has started, the action potential has already fired, stimularing the muscle fibers. Once they