Physio EX-02-06 PDF

Preview

Summary

Moore...

Description

Name: Lily Rosenblum Exercise 2: Skeletal Muscle Physiology: Activity 6: The Skeletal Muscle Length-Tension Relationship Lab Report Pre-lab Quiz Results You scored 100% by answering 5 out of 5 questions correctly. 1. During an isometric contraction You correctly answered: d. the skeletal muscle is generating force, but it remains at a fixed length. 2. The force that results from muscles being stretched is You correctly answered: a. passive force. 3. Active force You correctly answered: b. is determined by the amount of myosin bound to actin. 4. When you generate the isometric length-tension curve, which of the following forces will not be indicated on your screen? You correctly answered: c. tetanic force 5. Passive force in skeletal muscle is largely caused by You correctly answered: c. the protein titin.

10/07/18

page 1

Experiment Results Predict Question: Predict Question: As the resting length of the muscle is changed, what will happen to the amount of total force the muscle generates during the stimulated twitch? Your answer : a. An increase in muscle length will increase total force. Stop & Think Questions: Note the dip in total force at a muscle length of 90 mm as compared to the total force at a muscle length of 80 and 100 mm. Why does this occur? You correctly answered: d. At this muscle length, active force has decreased in value and passive force has not yet increased to a significant value. Experiment Data: Voltage

Length

Active Force

8.5 8.5 8.5 8.5 8.5 8.5

75 70 65 60 55 50

1.82 1.75 1.55 1.21 0.73 0.11

0.0 0.0 0.0 0.0 0.0 0.0

1.82 1.75 1.55 1.21 0.73 0.11

8.5 8.5 8.5

80 90 100

1.75 1.21 0.11

0.02 0.25 1.75

1.77 1.46 1.86

10/07/18

page 2

Passive Force

Total Force

10/07/18

page 3

10/07/18

page 4

10/07/18

page 5

10/07/18

page 6

10/07/18

page 7

10/07/18

page 8

10/07/18

page 9

Post-lab Quiz Results You scored 100% by answering 5 out of 5 questions correctly. 1. When a skeletal muscle is stimulated and generates force but remains at a fixed length You correctly answered: d. the muscle is contracting isometrically. 2. Which protein is mostly responsible for the development of passive force in a muscle? You correctly answered: d. titin 3. In skeletal muscle, active force stimulated through a range of muscle lengths You correctly answered: b. will utilize ATP hydrolysis to drive the cross bridge cycle. 4. Which of the following is not depicted in a typical skeletal muscle isometric length-tension curve? You correctly answered: a. time 5. Maximal active tension will be produced in a skeletal muscle fiber when You correctly answered: a. the fiber is at its resting length.

10/07/18

page 10

Review Sheet Results 1. What happens to the amount of total force the muscle generates during the stimulated twitch? How well did the results compare with your prediction? Your answer: The force is changed by the starting resting length of the muscle. If the passive force is increasedIf the muscle is lengthened past its resting length. If the muscle is shortened to its resting length, the active force increases. 2. What is the key variable in an isometric contraction of a skeletal muscle? Your answer: Muscle length because in isometric contraction, the muscle length does not change. 3. Based on the unique arrangement of myosin and actin in skeletal muscle sarcomeres, explain why active force varies with changes in the muscle's resting length. Your answer: Active force depends on the rate of combine between actin and myosin. 4. What skeletal muscle lengths generated passive force? (Provide a range.) Your answer: The range for skeletal muscle lengths generating a passive force is between 80-100 mm. 5. If you were curling a 7-kg dumbbell, when would your bicep muscles be contracting isometrically? Your answer: In situation when the bicep muscles fix its length.

10/07/18

page 11...