Muscle experiments lab

1. Placing my finger along my jaw line and then clenching my teeth. The jaw muscle seems to expand. Instead of the lower jaw muscle being smooth, there is a bulge in the skin under the ear where the jaw muscle expands out to the side of the jaw.


2. When the arm is extended fully the width of my thumb and finger fully stretched out goes from the elbow joint the full length of the upper bicep muscle. When I bend my arm so my hand comes back to my shoulder my finger and thumb get much closer to each other. The upper arm muscle is contracting and becoming smaller when my are is bent and then extending when my hand stretches back out to full length.


3. Using two strips of paper connected together I measured my bicep circumference. After clenching my fist the circumference of my arm muscles increase to ¾ inch longer then my arm muscles without a clenched fist.
Clenching the fist expands the upper arm muscles increasing there overall circumference.


Temp.
Normal 32 clenched fists in 20sec.
Cold water 41 clenched fists in 20sec.


Effect of Fatigue on Muscle action
Trial # of squeezes in 20 sec
1. 51
2. 45
3. 45
4. 37
5. 42
6. 38
7. 39
8. 37
9. 37
10. 37


1. What are the three changes you observed in a muscle while it is working (contracted)?
The three changes I observed is when I was flexing my upper arm bicep muscle was first the bicep brachii muscle contracted and became shorter as my forearm moved upward so my fist was close to my deltoid muscle. The bicep muscle gets shorter because the actin is moving across the myosin until the sarcomeres are fully contracted making the bicep muscle the shortest it can become.


The second thing I observed was the total circumference of my bicep brachii increased as I flexed the arm muscle. From my understanding of the contraction process as the thousands of sarcomeres start the process of contracting the actin begins to slide over the myosin. As this process happens it would make sense that the muscle would go from longer and thinner to shorter and bulkier. I think the increase in circumference is the result of thousands of sarcomeres fully compacted and slightly bulging then they were when the muscle was relaxed.


The third thing I observed is when I flex the bicep muscle as I bring the forearm up to meet my shoulder muscle the bicep muscle is not the only muscle at work. For every muscle I move or contract another one or more muscle are also moving with that muscle. When the bicep muscle is contracting and becoming shorter the triceps brachii is relaxed as possible to allow the opposite muscle to be as tight as possible. Its like that saying for every action there is an opposite reaction, it seems with muscles for everyone that does one thing there are multiple other muscles either doing the opposite or helping with the primary function (primary vs. synergist vs. antagonists).


2. What effect did the cold temperature have on the action of your hand muscles? Explain.
This little experiment was fun to try, at first I assumed I had done the experiment wrong because the results I got were different from what I expected. So I had my roommate try it and he got the same results. So I reviewed the chapter 12 material again and I think I now understand the results. From the data I collected you can see I was able to do more clenched fists after my hand was freezing cold from the water. I think there are a few primary reasons why this happened. One is homeostasis, when my hand was in the ice cold water the core temperature of my hand decreased the longer my hand was in the water. Since my body automatically wants to get that temperature back to where it should be my hand wants to do work. As the muscles in my hand use ATP to contract they are doing work, as the muscles do work they are producing heat as a by product of work. So as soon as I withdrew my hand from the water and started making fists I could go faster because my hand muscles were eager to start heating up and therefore getting that temperature back to normal. When people are in a very cold environment they start to shiver and naturally clench there fists and tighten up there muscles almost automatically. I think this helps explain the situation as we shiver are muscles are again contracting and trying to produce enough heat to raise the body temperature back up. I would guess if you were really cold you could do a few more pushups then if you were in a hot environment where the muscles said we are as hot as we want to be so they don’t want to do as much activity, they you have to start sweating the keep the temperature down.


3. Why at the cellular level would cold and fatigue affect muscular action?
Being in cold weather or under strenuous physical activity will cause a strong response from the nervous system and how your muscle will react. In cold conditions the body temperature will decrease as the environmental conditions your are in decreases. The body does not like this and will automatically want to raise the core body temperature back up to normal levels to maintain homeostasis. To accomplish this on the cellular level the cells will want to start using energy and doing work to produce body heat. An example of this could be shivering or tightening of muscles. The results from the cold water and fist experiment shows the body wanting to perform functions quickly which will help to raise the temperature. The more the cells in your body produce ATP for use by the muscle cells in contracting and relaxing the muscles of the body the more heat the body can produce. With physical activity the body is also going to experience some effects to the nervous and muscular system. When we start doing physical activity the body and respiratory system start working harder to get red blood cells and oxygen to the different muscles which need them most. If we are doing hard physical activity the body and cells may not be able to produce enough ATP for the muscle cells and oxygen for the regular cells to make the ATP, thus fatigue starts to set in. We have three main sources for the body to get energy and depending on what type of activity your body is used will determine which of the three sources you will use of first. If you are doing short bursts of activity the creatine phosphate pathway may be the first source of energy but once it is depleted fatigue will set in quickly. If you are a runner then your body will mostly run on cellular respiration especially if you have trained the body to build up excess stores of ATP and a larger production of cellular respiration. This source is a good steady supply and will take a long time to deplete. Fermentation is another source of energy for the muscles to use during activity. When I did the cloths pin experiment I was able to maintain and level number of reps even though my fingers were feeling the strain, this is because even though my finger muscles and forearm muscle were feeling fatigue at the cellular level only a certain percentage of muscle cells were fatigued. When we use are cellular muscles they do not all contract at once with every myofibril being used at the same time. Some are used for a certain period and then they rest and others take up the role, in this way your muscles will start to become fatigued but it’s the bodies way of saving some energy to keep up that movement as long as possible. This is a great evolutionary trait to have selective cellular muscles being worked and not all at once, allowing us to perform functions for extended periods before experiencing extreme muscle fatigue.