Skeleteal Muscle part 3 Flashcards
Describe skeletal muscle energy stores.
Glycogen and creatine phosphate.
Describe the creatine kinase reaction
Substrates: ADP, phosphocreatine
Products: ATP creatinine
Enzyme: Creatine kinase
What are the muscles other two energy pathways?
Glycolysis and oxidative phosphorylation; Supplies most of the energy for contraction.
Relate the frequency of an action potential to the force of contraction.
Direct relationship
Discuss Tetanus
Muscle producing a sustained contraction rather than individual twitches; Does not recruit additional skeletal muscle.
Describe spatial summation
Increasing the total force of contraction by increasing the number of active motor units.
Relate neuron cell body size to depolarization thresholds
Direct relationship; Smaller cell bodies lead to lower depolarization thresholds. Smaller neurons are recruited before larger ones.
Which neurons are recruited first?
Type 1 motor units are first, then Type 2.
Describe the 3 types of contractions.
- Isometric: Muscle develops tension but cant shorten.
- Concentric: Muscle develops force and shortens.
- Eccentric: Muscle develops force and lengthens.
What is an isotonic component?
An aspect of concentric and eccentric contractions that allows muscle to shorten or lengthen but maintain a constant force.
Discuss isometric contractions
Myosin heads rotate and pull actin but the sarcomere doesnt shorten; Force produced matches external load.
Discuss concentric contractions
Myosin head pulls actin and sarcomeres shorten; Force produced exceeds external load.
Discuss eccentric contractions
Myosin heads pull actin and sarcomere lengthens; Muscle strenghtening is enhanced during this exercise. Can lead to muscle damage.
What is a first class lever?
Fulcrum is between the resistance and effort; Atlanto-occipital joint. See-saw
What is a second class lever?
The resistance is between the fulcrum and the effort; foot.
What is a third class lever?
The effort is between the fulcrum and the resistance; Elbow
Define the maximal force as well as the optimal length.
Maximal Force: All the myosin are overlapped with thin filaments
Optimal Length: The muscle length that allows for maximal force.
Define Total force
Total force = Passive + Active force
Describe the Force-velocity relationship
Muscle can shorten at different rates depending on the load; The heavier the load, the slower the shortening.
Define Vmax
The maximum possible shortening velocity for a muscle; Occurs in the absence of a load
Define Fmax
Maximum force which can be generated by a muscle; Equals the isometric force
Relate eccentric muscle force to Fmax
Force produced by eccentric muscle contractions is greater than or equal to Fmax
Relate the muscle fiber length to the speed of contraction.
Direct relationship
