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PhysioExActivity6
The skeletal muscle length-tension relationship
| Question | Answer |
|---|---|
| What type of contractions do skeletal muscles produce? | Isometric or Isotonic |
| What happens to the muscle during isometric contractions? | The muscle stays at a fixed length . When a muscle attempts to move a load that is equal to the force generated by a muscle, the muscle contracts isometrically |
| Give an example of an isometric muscle contraction | When you push on a doorframe, the load you are attempting to move can easily equal the force generated by your muscles so your muscles do not shorten even though they are actively contracting |
| How can isometric contractions be accomplished experimentally? | By keeping both ends of the muscle in a fixed position while electrically stimulating the muscle |
| How is passive force generated? | Stretching the muscle and results from the elastic recoil of the tissue itself |
| What is resting length? | The length of a muscle before stimulation |
| What does resting length determine? | The amount of force a muscle can develop when stimulated |
| What is passive force caused by? | The protein titian |
| How is active force generated? | When myosin thick filaments bind to actin thin filaments thus engaging the cross bridge cycle and ATP hydrolysis |
| Describe the skeletal muscle's 2 force properties | It exerts passive force when it is stretched & active force when it is stimulated |
| What is the total force? | The sum of active and passive forces |
| Describe the isometric length-tension relationship | A graph relating the 3 forces generated to the fix length of a muscle will be automatically plotted after the muscle is stimulated |
| How can the results of this experiment be applied to human muscles? | To understand how optimum resting length will result in maximum force production |
| Maximal active tension will be produced in a skeletal muscle fiber when | When the muscle finer is at its resting length |
| What happens to the amount of total force that the muscle generates during the stimulated twitch? | Total force is altered by the starting resting length If the muscle is lengthened the passive force ^ &if the muscle is shortened the active force increases. With each force (a&p) the total force is changed depending on the amount of either A or P forces. |
| 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. (1) | When the resting length of the muscle is shortened, the active force amount increases. When the resting length of the muscle is lengthened, the active force amount decreases. |
| What is the change in active force caused by? | The change in the active force amount is completely caused by the amount of myosis bound to actin. The shorter the muscle’s resting length is, the more myosis filaments bind to actin filaments. |
| What range of skeletal muscle lengths generated passive force? | 80, 90 & 100 |
| If you were curling a 7-kg dumbbell, when would your bicep muscles be contracting isometrically? | At any point in which the bicep muscle remains at a fixed length. My best example is holding 2 dumbbells parallel to the floor and holding them in that position for 30 seconds. The muscles are contracting but are not shortening. |
Created by:
meunid