Sec. Nan1e: _

! Experiment: Muscle Cells & Muscle Contractions, (S. Science 10-36-2d)

Purpose: To observe the three types of musclestissue,to learn that electrical impulses initiatemuscle contractions, and to see that skeletalmuscles work in pairs.

Materials: polygraph (EMG) frog dissection kit

Methods:

Part A: Electrical activity of muscles .•__ 0_ •• :(Electromyograph EMG)

1. Rest your arm on the desk with your hand facing up and then hook up elBCtrodes tothe muscle of arm. Notice a fairly regular electrical pattern, now move your arm.2. Record the results of EMG while resting then moving.Part B: Tendon and Muscle Relationship1. Place a frog on the dissecting pan belly up. Cut the skin around the leg right nearwere it connects to the abdomen. Peel back the skin, like rolling a sock off your foot, toexpose the muscles of the leg.2. Find the tendons attached to the muscles on the front of the "thigh" portion of theleg. (Tendons are the tough, shiny white cords, that join the muscles to the bones).Pull on the muscle, observe and record the motion of the leg.3. Repeat step two, but with the back of the leg.Part C: Making Basic Observations and Measurements.1. While sitting quietly, rest your right arm on your desk with thepalm of your hand up. Place your left hand lightly around yourright arm as shown in the figure. Make a fist and lightly bend (flex)your right arm. Explain the changes you feel taking place in theright arm. Include muscle names of the front and back of the arm.2. Now, fully straighten (extend) your arm. Describe the changesyou feel with muscles on the front and back of arm.3. What observation show that skeletal muscles work in pairs?4. With the aid of charts or your text, identify the flexor muscle (muscle to move armup) involved in the activity. Also label this in the diagram.5. Name the extensor muscle used to straighten arm, also label this in the diagram.6. Where are these muscles attached? Label the bones of the arm as well.7. What type of joint does this movement take place in?8. What must occur in the cells (fibers) of the biceps when the arm is flexed?9. What must occur in the cells (fibers) of the triceps when the arm is flexed?

Results:Part A: Electrical activity of muscles.resting electrical activity:Part B: Tendon and Muscle Relationship2. leg motion when pulling on front :

active:

See. Name: _3. leg motion when pulling on back :Part C: Making Basic Observations and Measurements.1. flexing observations:

2. extending: _3. observations of pairs:4. flexor muscle: _5. extensor muscle:6. biceps:

triceps:7. joint: _8. cell action of biceps:9. cell action of triceps:

Conclusions:1. Explain the statement: "Skeletal muscles that move joints work in opposite pairs".

2. The point of contact between a motor neuron and a skeletal muscle cell is a(an)

3. What stimulates the muscles to contract?4. What causes the muscles to lengthen?

Discussion: Fill in the blanks.1. An extensor muscle a joint, while a flexor muscle_______ a joint. Skeletal muscles are under our control and are said to be______ , while smooth muscles are not under our control and are referred toas . Increasing our muscular activity will also increase themuscle's need for and . In times of increasedmuscular activity, coordinated activities of the respiratory and circulatory systems serveto bring in additional nutrients. They also serve to speed up the removal of cellularwastes, including . The contraction of the _causes the elbow to bend. The contraction of the straightens thearm at the elbow joint.

2a. During a race there is rapid muscle contractions. Read I Cor 9: 23 - 27. In theChristian race how should we run (vs. 23, 24)?

3b. Athletes under go strict training to develop muscles so they can win the prize.Does this prize (crown) last for ever? (vs 25)

9c. How long does the Christian prize last (vs 25)?

9d. According to verses 26 - 27, record some of the phrases describing the intensity ofeffort the author uses in competing in the Christian race for the eternal prize.

ge. When we face the end of our Christian race here on Earth (death) my prayer is thateach of us can quote 2 Tim. 4:7 to sum up our Christian experience. Write this text out.