1. 21 October 2009 This Week in Physiology:
Wednesday Quiz: Cranial Nerves
Lab: Sensory Physiology & Auditory System
Lectures: Ch. 9 Muscle Physiology
Starting Wednesday after Fall Break: 1 Question Quiz each class meeting based on the previous lecture.

2. Energy for powerstroke & Necessary for detaching myosin from actin
Fig
2 roles of ATP:
Energy for powerstroke &
Necessary for detaching myosin from actin
Crossbridge cycling continues as long as ATP and Ca++ present.
09.08.jpg

3. YouTube Videos Role of ATP in muscle Creepy Muscle demo Sarcomere contraction Powerstoke in muscle I Powerstroke in muscle II
09.09.jpg

4. Muscle kinetics
Link to cytosolic calcium concentration, release, and reuptake?
09.10.jpg

5. Fig
09.16.jpg

6. Fig a
Twitch
Twitch
Twitch
09.19a.jpg

7. Fig b
Summation
09.19b.jpg
Tension is a result of the temporal control of cytosolic calcium concentration

8. Fig c
09.19c.jpg

9. Fig
Why does this plateau?
09.20.jpg
So….. Tension produced by a single myofiber varies depending on frequency of Action Potentials.

10. Length-tension Relationship
09.21.jpg
So….. Tension produced by a single myofiber varies depending on sarcomere length.

11. So what are the ways a muscle (consisting of many myofibers) increases tension (force)?

12. Fig
Motor unit = a single somatic motor neuron and all the muscle fibers in innervates
09.13.jpg

14. Increasing tension in a whole muscle
Frequency of stimulation of motor neuron
Activate larger motor units
Recruitment: activate more motor units
These factors influence actual tension
Fiber length (length-tension) relationship
Fiber diameter
Level of fatigue (state of activity)