report

MUSCLE LAB REPORT

ANATOMY& PHYSIOLOGY

INTRODUCTION
Muscle action is often described as departures from the standard position of the body, the anatomical position. Muscle fiber is an interaction of organelles and molecules within myosin binds to actin and exerts a pulling action. The result of this movement with myofibrils in which the filaments of actin and myosin slide past one another. This action shortens or contracts muscle fiber so that it pulls on its attachment. Muscle are stimulated by a chemical reaction called acetylcholine, it synthesizes in the cytoplasm of a motor neuron and stored in vesicles at the distal end of the motor neuron axons. Each muscle fiber is packed with myofibrils, which is bundles of contractile filaments made up of actin and myosin. A longitudinal view of a myofibril reveals the reason for the striated appearance of skeletal muscle and cardiac muscle. The myofibril consists of repeating units, called sarcomeres, which are the units of contraction. Each sarcomere is made of overlapping filaments of actin and myosin, which create a distinct band pattern. As the muscle contracts, the sarcomeres shorten, and the appearance of the band pattern changes. When the muscle contracts, the sarcomere shortens. The H zone and the I band become much narrower, and the Z lines move toward the A band as if the actin filaments. When a muscle is stimulated, a short latent period follows, during which it is taking up the stimulus. It then contracts, where it becomes short and thick, and finally it relaxes and elongates. Muscles can also become fatigued meaning that if a muscle has being strenuously exercised for a prolonged period may lose its ability to contract. The interruption in the muscle’s blood supply or if ,lack of acetylcholine in motor neuron axons may cause fatigue , however fatigue is mostly arise from accumulation of lactic acid in the muscle as a result from a strenuous breathing. The lactic acid buildup lowers PH and as a result, muscle fibers no longer respond to excitability. On an occasion a muscle becomes fatigued and cramps build up at the same time. Cramps can cause abnormal stimulation of the muscle due to extracellular fluid surrounding the muscle fibers and their motor neurons. Temperature has an effect on the muscle, during the contractile process, the influence which a rise or fall of temperature will have on muscular activity may be anticipated from the effects such changes would have on these separate processes. We know that for each rise of ten degrees in temperature chemical reactions are only increased in rate from two to three times while physical reactions are only increased once. The rate of development of an isometric twitch has a temperature coefficient of about 2.5 for each ten degrees Centigrade, while the same coefficient for its subsidence is about 3.6. The development of energy in contracting muscle is associated with a chemical change, the production of acid. The immediate neutralization of this acid is likewise a chemical reaction as is also the recovery phase of the muscle. The mechanical changes undergone by the contracting muscle involve physical adjustments. Heat, then, within certain limits accelerates all phases of the muscular contraction; the latent period is shortened, the rapidity and effectiveness of the contraction are increased while the relaxation phase is especially accelerated. Cold has opposite effects. These again are most pronounced on the relaxation phase which becomes progressively slower and more prolonged as the temperature is lowered until a critical minimum temperature is reached. At this temperature the properties of irritability and contractility are reversibly suspended. The most favorable temperature for muscular activity is about one degree above the normal body temperature. I observed three changes one being the hardness of the muscle, the buccinator seemed to have expanded and when I let go, the buccinator goes back to shape which shows that it can extract and retract. 2,As I extended the muscle would pull back and come together when flexed. And would get short as I did the action. 3,The measurement of my upper arm was 28cm long ,then my new circumference was 26 cm.

PROBLEM/HYPOTHESIS

They are two problems that we worked on as our lab , the first problem asks what effects does temperature have on muscle action. And the other problem asks what is the affect does fatigue have muscle action. According the intro temperature affects the muscle according to the condition heat or cold , both have different effects on muscle action. And muscle fatigue is caused due to strenuous exercise for a prolonged period of time then losing its ability to contract. And that if interrupted in the muscle’s blood supply may cause lack of acetylcholine in the motor neurons that being the main cause of fatigue in the muscle. My hypothesis for the first problem is that muscle function will increase after getting out the hand out of cold ice water. And for the second problem the number of contractions will decrease as the time moves , that being that fatigue affecting the ability to contract.

DATA
The following data is separated into table A and table B
THE EFFECT OF TEMPERATURE PROCEDURE A (TABLE A)
Trial
1
2
3
Average
normal
37
45
55
45
After ice water
50
40
45
45

THE AFFECT OF FATIGUE ON MUSCLE ACTION(PROCEDURE B) TABLE B

Trial
Seconds
Number of squeezes
1
20
56
2
40
40
3
60
24
4
80
28
5
100
24
6
120
30
7
140
36
8
180
27
9
200
21

CONCLUSION
First problem asks what effects temperature has on muscle action. And the other problem asks what is the affect does fatigue have muscle action. According the intro temperature affects the muscle according to the condition heat or cold , both have different effects on muscle action. And muscle fatigue is caused due to strenuous exercise for a prolonged period of time then losing its ability to contract. And that if interrupted in the muscle’s blood supply may cause lack of acetylcholine in the motor neurons that being the main cause of fatigue in the muscle. My hypothesis for the first problem is that muscle function will increase after getting out the hand out of cold ice water. And for the second problem the number of contractions will decrease as the time moves, that being that fatigue affecting the ability to contract. The data supported my hypothesis that after putting your hand in ice cold water increases the number of contractions. And fatigue has effect on muscle action. Temperature has an effect on the muscle, during the contractile process, the influence which a rise or fall of temperature will have on muscular activity may be anticipated from the effects such changes would have on these separate processes. We know that for each rise of ten degrees in temperature chemical reactions are only increased in rate from two to three times while physical reactions are only increased once. The rate of development of an isometric twitch has a temperature coefficient of about 2.5 for each ten degrees Centigrade, while the same coefficient for its subsidence is about 3.6. The development of energy in contracting muscle is associated with a chemical change, the production of acid. The immediate neutralization of this acid is likewise a chemical reaction as is also the recovery phase of the muscle. The mechanical changes undergone by the contracting muscle involve physical adjustments. Heat, then, within certain limits accelerates all phases of the muscular contraction; the latent period is shortened, the rapidity and effectiveness of the contraction are increased while the relaxation phase is especially accelerated. Cold has opposite effects. These again are most pronounced on the relaxation phase which becomes progressively slower and more prolonged as the temperature is lowered until a critical minimum temperature is reached. At this temperature the properties of irritability and contractility are reversibly suspended. The most favorable temperature for muscular activity is about one degree above the normal body temperature.
Muscles can also become fatigued meaning that if a muscle has being strenuously exercised for a prolonged period may lose its ability to contract. The interruption in the muscle’s blood supply or if ,lack of acetylcholine in motor neuron axons may cause fatigue , however fatigue is mostly arise from accumulation of lactic acid in the muscle as a result from a strenuous breathing. The lactic acid buildup lowers PH and as a result, muscle fibers no longer respond to excitability. On an occasion a muscle becomes fatigued and cramps build up at the same time. Cramps can cause abnormal stimulation of the muscle due to extracellular fluid surrounding the muscle fibers and their motor neurons.
Some errors that we experienced were, miscounting or not paying attention to the other person. If your partner kept moving their hand instead of staying of staying one place. And getting confused on how many number of squeezes we had to do.