MUSCLE LAB - Weebly



MUSCLE LAB

1. PROPRIOCEPTION

Even with your eyes closed, we have a sense of body position- where are arms and legs are, for example, and that we are moving them. Muscles, tendons, joints and the inner ear contain proprioceptors, also known as stretch receptors, which relay positional information to our brains. Our brains then analyze this information and provide us with a sense of body orientation and movement.

For these two activities, you & your partner will take turns. Person 1 will read and explain the procedure to person 2 and then you will switch off.

Activity 1: Finding Fingertips

Close your eyes and raise both hands above your head. Keep the fingers of your left hand totally still (no wiggling!). With your right hand, quickly touch your index fingertip to your nose, then quickly bring that fingertip back up and touch your left thumb. Quickly repeat this process (nose, finger, nose, finger, etc.) while attempting to touch each of the fingers on your left hand in succession.

After you have touched all five fingers of your left hand with your right index fingertip, switch hands and try again.

Now that you completed this activity with both hands, repeat the whole process but this time, wiggle the fingers that stay in the air while your other hand goes from your nose to each finger and back to your nose.

How successfully did you find each fingertip? Was there a difference when different hands were used? Was there a difference when you “wiggled” the fingers in the air? (Discuss the results with your partner)

Muscle Action:

Place your fingers along the angle of your jaw just in front of your ear. Grit your teeth and observe what happens to your muscles when they contract.

1) What do you observe? (write answers to questions on lined paper)

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.

2) What do you observe?

(Guys-this is your chance to impress the ladies with your beach muscles) Wrap a strip of paper around your relaxed upper arm and mark the circumference of your arm on the paper. Clench your fist tightly, move your fist towards your shoulder and and flex your biceps brachii. Try to rip the paper. If you cannot, hold your head in shame and mark the new circumference on the paper.

3) What do you observe in your biceps brachii?

Activity 2: X marks the Spot

Mark an “X” on a piece of paper. Keep the paper on the desk in front of you. Pencil in hand, raise your hand above your head, close your eyes and make a dot as near as possible to the “X.” Open you eyes and check your success. Raise your hand above your head, close your eyes, and attempt to make a dot closer to the “X.” Do this several times. Repeat with your eyes open.

What did you observe through this process? (Discuss the results with your partner)

Tonus:

The muscles of the body are normally in a state of continual and mild contraction. This is known as muscle tone or tonus, and can be detected by feeling a slight rigidity of the muscle. Palpate muscles (feel or massage) in the different regions of your body to detect the presence of tonus.

Tonus is concerned with the maintenance of body posture. While sitting erect, relax the abdominal muscles.

4) What is the effect on posture of voluntarily relaxing these muscles?

Next, observe the position of the mandible when it is allowed to fully relax. Hint: What usually happens to your mouth when you fall asleep while sitting up?

5) When the mandible is fully relaxed, what is its position?

6) Explain how tonus is concerned with the posture of the jaw when one is conscious and alert?

7) When do you think tonus is normally at a minimum?

Activity 3: Handwriting Analysis

On a sheet of lined paper, write the word “muscle.” Place your pencil on the same line next to the written word, close your eyes, and write “muscle” again.

What difference, if any, do you see between the two words? (Discuss the results with your partner)

Isotonic and Isometric Contractions:

8a) Explain what isotonic contractions and isometric contractions are. (Look this up on your Ipad or ck12, don’t ask your teacher!)

8b) Give two examples for each type of contraction.

9) What is the advantage of isometric exercise?

10a) What is the main advantage of isotonic contractions?

10b) What impact does it have on cardiac and skeletal musculature?

Activity 4: Fatigue

Fatigue is a state of loss of excitability of a muscle or a group of muscles. Physiologists also recognize psychological fatigue. Holding a heavy object can induce fatigue. A textbook will be a perfect tool to help illustrate this concept! This is a timed exercise so have your partner get the stopwatch ready. Grasp two textbook between the fingers and thumb (fingers should be superior to the thumb; thumb should be inferior to the fingers).

Extend the arm laterally (START TIME) and as soon as your arm sinks half way down, STOP the time.

11) How long were you able to keep your arm holding the textbook extended?

12a) If a tourniquet was placed on your upper arm prior to the activity, how do you suppose depletion of the blood supply would affect your endurance? What does blood supply to the muscles that they need?

12b) WHY?

13) Indicate two factors which can contribute to fatigue and how do they contribute?

Activity 5: Effect of Fatigue on Muscle Action

Look at the following data collected when a student opened and closed a clothespin with their thumb and index finger for 10 trials, each trial lasting 20 seconds. Each trial was conducted in quick succession without a break or rest.

|TRIAL |# closures / 20 sec. |

|1 |42 |

|2 |38 |

|3 |41 |

|4 |36 |

|5 |34 |

|6 |32 |

|7 |31 |

|8 |31 |

|9 |29 |

|10 |28 |

[pic]

14) What effect did fatigue have on the action of this person’s hand muscles?

Grab one of the two red squishy hearts and squeeze it as hard as you can 30 times while your partner times you. Wait only 5 seconds. Now, immediately squeeze it as hard as you can another 30 times while your partner times you

15a) After squeezing the heart the second time for 30 seconds, how did your arm feel?

15b) How does this feeling relate to “oxygen debt” and lactic acid formation?

Activity 6: Muscle Sounds

Some muscle, such as the masseter (cheek) and the biceps bronchii, emit detectable sounds on contraction. These sounds can be heard in a perfectly quiet area (step just outside the room) when a stethoscope is placed over the area of the muscle. The stethoscope can be placed over the side of the face at about the region of the third molar (last tooth). You may also use the biceps of the anterior portion of the upper arm. Place the stethoscope on your upper arm where the muscle forms a bulge as you flex your arm. Each student should attempt this observation, taking note of the frequency of the sounds and whether or not the quality of the sound changes as these muscles are intensely contracted.

16) Describe what it sounds like to you.

17) Did you notice any difference in the sounds made by the cheek muscle as compared to the biceps?

18) Explain why sounds are made when muscles contract.

Activity 7: Cool!

Stand in the doorjamb and stand straight. Abduct your arms until they hit each side of the doorjamb. Push with both arms as firmly as you can for 1 minute. Immediately after the time has elapsed, step into the classroom and consciously relax. THIS EXPERIMENT WILL NOT WORK IF YOU CONSCIOUSLY OVERRIDE THE EFFECTS OF THE ARM AT COMPLETE REST!

19) What happened when you stepped into the room and relaxed?

20) Explain why this type of reaction occurred? What caused it?

Activity 8: Effect of Temperature on Muscle Action

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 on your Lab Answer Sheet.

Now submerge your hand in a bucket of ice water and leave it there for one full minute. Be tough!

Remove your hand and immediately count how many forceful fists you can make in 20 seconds. Record your data in Figure 1.

21)

|Temperature |Number of Fists |

|Normal | |

|Ice Water | |

Figure 1:

22) What conclusions can you draw?

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