Lab 3 Muscle Action

Lab 3 Unit 3

Introduction:

The human body heavily relies on the contraction and relaxation of skeletal muscles.  This experiment will allow you to observe the characteristics of muscle contraction and also the effects that cold and fatigue have on muscles. 

                                                  

(http://163.178.103.176/CasosBerne/3cMusculo/Caso12-1/HTMLC/CasosB2/ATP/amuscle.html, accessed 13 April 2012)

Materials:

Ice  *  Clothes pin  *  Timer  *  Bowl of Water  *  Thin Strip of Paper (that loosely fits around you bicep)

Muscle Action

One way to feel how a muscle contracts is by placing your fingers along the angle of your jaw just in front of your ear and then clenching your teeth together.  When you clench your teeth together your jaw becomes hard with your jaw muscles contracted.   

Another way to observe muscle contraction is to take a thin piece of paper that can loosely fit around your bicep muscle in your arm.  When your arm is relaxed take the piece of paper and wrap it around your arm marking the circumference. Next flex your bicep muscle and mark the circumference of your arm now.  What happened to your muscle circumference?

(http://health-pictures.com/muscle/muscle-contraction.htm, accessed 13 April 2012)

Effect of Temperature on Muscle Action

What effect does cold have on our muscles?   First I opened and closed my hand as many times as I possibly could within twenty seconds, extending my hand open as far as possible. In the next part of the exercise a pan of almost freezing ice water was prepared.  Then I placed my hand in the ice water for one complete minute.  As soon as the minute was up I repeated the first part of the exercise, completely opening and closing my hand as many times as I could within twenty seconds.

This is the number of times I opened and closed my hand.

Room Temperature______33______                   Ice Water______29_______

 

Effect of Fatigue on Muscle Action

In the table below each number represents the number of times a close pin was opened and closed within twenty seconds.  The exercise was preformed ten consecutive times without rest in between for both the right and left hand. 

Right Hand	Left Hand
1.  50	1.  45
2.  49	2.  46
3.  48	3.  45
4.  48	4.  42
5.  50	5.  42
6.  50	6.  45
7.  48	7.  46
8.  47	8.  44
9.  47	9.  42
10.  49	10.  43

Analysis of Data

1.      1.   What are the three changes you observed in a muscle while it is working (contracted)?

I observed that while my muscle was contracted that it was very hard, compact, and noticeably bulged out more than when relaxed.   

2.    2.     What effect did the cold temperature have in the action of your hand muscles?

It was painful to keep my hand in the ice water for a full minute.  After twenty seconds my hand began to burn and it was very intense.  When I pulled my hand out of the ice bath and began to perform the experiment of completely opening and closing my hand for twenty seconds it was difficult in the beginning.  It was like watching a movie in slow motion.  Once about eight seconds had gone by I could feel my muscles warming up and my hand was moving much faster. 

I researched and found that cold water makes the muscles and tissues contract, thus reducing the size of transportation channels of blood and nutrients and so slows/impairs movement. (http://wiki.answers.com/Q/Why_does_cold_water_effect_the_muscles, accessed 14 April 2012)

3.      3.  What effect did fatigue have on the action of your hand muscles? Explain

I originally used my right hand to perform the close pin experiment and never had any feelings of discomfort or fatigue.  I then decided to also perform the experiment on my left hand as well.  When doing the experiment on my left hand I felt discomfort and felt my muscles begin to ache in my forearms on the 9^th and 10^th time performing the experiment.  Fatigue made it more difficult to close the close pin and my muscles to be sore the following day in my forearms. 

4.     4.   Explain why at the cellular level you think cold and fatigue would affect muscular action.  Include what’s happening to the actin and myosin, to calcium release.

At the cellular level, muscles begin relaxing due to fatigue even when my body is telling those muscles to keep contracting.  Muscle fatigue is contributed to the depletion of glucose in the body and the buildup of lactic acid.  The cold slows down the chemical actions and reactions needed for muscular contraction.  A sarcomere consists of two types of proteins.  One of those proteins is myosin that is at regular intervals within filaments of the other protein actin. The interaction of the two proteins determines muscle contraction.  

(http://www.nerdylorrin.net/jerry/politics/Nuke/teach.html, accessed 13 April 2012)

Conclusion

In conclusion I observed that when you reputably do a motion that uses skeletal muscles fatigue sets in.  Depending on if a person exercises and is used to using specific muscles determines how quickly their muscles will fatigue.    The cold slows the body’s reaction time down.    I learned that muscles are much more complex than I had originally thought.  I was amazed that after taking my hand out of the cold water my body recovered so quickly.