Lecture Objectives for: Force Modulation in Skeletal Muscle

Question 1

explain why the y-axis can show either muscle tension or muscle shortening

Answer 1

As the myosin heads pull the actin filaments, the sarcomere shortens- creating the tension of the muscle contraction. The cross-bridges can only form where thin and thick filaments already overlap, so the length of the sarcomere has a direct influence on the force generated when the sarcomere shortens → Length-tension relationship

Question 2

Describe how changes in recruitment, frequency, summation, and tetanus interact to modulate while muscle force?

Answer 2

Wave summation: By coupling successive motor neuron signals together, increased and fast paced recruitment can cause for successive graded potentials to become summative
Tetanus: By increasing the frequency of motor neuron signals, the relaxation phase can be lost can cause tetanus.

Question 3

Differentiate between the contractile, parallel elastic, and series elastic components of skeletal muscle

Answer 3

• Contractile: responsible for active tension- the myosin/actin complex
• Parallel Elastic: responsible for passive tension
• Series Elastic: must be stretched in order to develop active tension