MSK 21 - Muscle Physiology-II Flashcards
Misconceptions about contraction.
What is preload and afterload?
Preload represents all the factors that contribute to passive tension in the muscle at rest. It may also refer to the load on a muscle in a relaxed state, prior to contraction.
Afterload represents all the factors that contribute to total muscle tension during isotonic contraction. It may also refer to the load the muscle is working against or trying to move during stimulation.
Draw the force vs time graph of a twitch contraction. Label every phase of the graph and indicate which regions are active and passive force.
What is an isometric contraction? What causes it?
What do the force vs time and length vs time graphs look like for an isometric contraction?
Draw out the force vs time and length vs time graphs for an isotonic contraction and label every point/phase. What is occuring within a sarcomere at each point/phase?
What causes contraction and relaxation during an isotonic muscle contraction?
Changes in the cytosolic [Ca++] of muscle cell
What creates the passive/resting force/preload in a skeletal muscle?
What do the force length curves look like for a given skeletal muscle’s resting force, active force, and total force?
T/F - preload is directly proportional to muscle length.
It is proportional but NOT directly proportional
A skeletal muscle is fixed at a specific length, stimulated, and the force generated is measured. The muscle is then fixed at a different length and the process is repeated. This is done for 5 different muscle lengths. Draw the resulting force vs time graph and describe what each point/region indicates.
What type of muscle contraction does this graph indicate? Label the point that corresponds to afterload
Isotonic contraction
