this lab is important because it helps you realize just how much cold and fatigue affect your muscle performance.
How Do Your Muscles Work?
Name__Rebecca M__ Date__7-22-08__
INTRODUCTION:
Much of the work of the body depends on the contraction of skeletal muscles. In this experiment you will first observe the characteristics of muscle contraction and then will investigate the effects of two factors - temperature and fatigue - on the action of your muscles.
MATERIALS:
dishpan of water narrow strip of paper which will fit around upper arm ice or snow rubber ball or clothespin timer (clock, watch, or stop watch)
PROCEDURE:
The following exercises will help you understand what happens to your muscles when they contract.
Muscle Action
1. Place your fingers along the angle of your jaw just in front of your ear. Grit your teeth and observe what happens to the hardness of the muscles in your cheek.
2. With the thumb and little finger of one hand, span the opposite arm's biceps (front muscle of the upper arm) from the elbow to as close to the shoulder as possible. Bend the arm and observe the change in the length of the muscle.
3. Wrap a strip of paper around your upper arm and mark the circumference of your arm on the paper. Clench your fist tightly and mark the new circumference on the paper. Observe what happens to the circumference of the muscle.
Effect of Temperature on Muscle Action
1. Count the number of times you can make a fist in 20 seconds. Start with your hand completely outstretched and make a tight fist each time. Do it as rapidly as you can. Record the count in Figure 1.
2. Now submerge your hand in a dishpan of water to which has been added snow or ice so that the temperature is near the freezing point. Leave your hand in the water for one full minute.
3. Remove your hand and immediately count how many forceful fists you can make in 20 seconds. Record in Figure 1.
Figure 1:
Effect of Temperature on Muscle Action
Temperature Number of Fists
Normal ------------------------------42
Ice Water ----------------------------14
Effect of Fatigue on Muscle Action
1. Count how many times you can tightly squeeze a rubber ball in your hand in 20 seconds. Record in Figure 2.
2. Repeat the squeezing nine more times and record results. Do not rest between trials. (An alternative procedure which works well is to open and close a clothespin with the thumb and index finger while the other fingers are held out straight.)
Figure 2: Effect of Fatigue on muscle action
Trial # of Squeezes in 20 seconds
1 -----------------------39----------------- ----------------------------------------
2 -------------------------37--------------- ----------------------------------------
3 ----------------------------34------------ ----------------------------------------
4 -------------------------------35--------- ----------------------------------------
5 ---------------------------------26------- ----------------------------------------
6 ------------------------------------36---- ----------------------------------------
7 ---------------------------------------37- ----------------------------------------
8 ---------------------------------------- -40---------------------------------------
9 ---------------------------------------- ----40------------------------------------
10 ---------------------------------------- ------35----------------------------------
ANALYSIS OF DATA:
1. What are the three changes you observed in a muscle while it is working (contracted)?
changes in how hard, how long, and how big muscle is.
2. What effect did the cold temperature have on the action of your hand muscles? Explain.
the cold temperature affected the muscles by decreasing the amount of heat that is conducted throughout the cells in the hand which slowed it down considerably and made my hand quite stiff.you should try this while playing a game of volleyball on a cold night and see what happens:D(your hand will be so stiff and hard that you can serve the volleyball REALLY far...)
3. In Figure 3, make a line graph of your results of the fatigue experiment. Be sure to fill in the values on the vertical axis.
Figure 3: Graph of Effect of Fatigue on Muscle Action
4. What effect did fatigue have on the action of your hand muscles? Explain.
_fatigue is the end result of what happens when you push your body to the limit (also known as anaerobic metabolism), so when I fatigued my hand I used up most of the energy within my hand, making it too tired to properly function.
cold makes the sarcomeres tighten, which means that the actin and myosin are tightly packed so they can't slide as easily.Fatigue would exhaust all the ACh,which then has to be replenished to trigger more contraction, which will take some time.
