Okay so I am brand new to this site and it looks like it is a great site. I hope so cause I need some help. As the subject says, I need the answers to exercise 16b skeletal muscle physiology: computer simulation. I have marieb's A&P book and lab manual, 10th edition, fetal pig version. This is due tomorrow and I have no idea what is going on with this. Anyway, I will post the questions and hope for some answers.
1. Name the three phases of a typical muscle twitch, and describe what is happening in each phase.
latent, contraction, and relaxation
2. In Activity 2, how long was the latent period? ________msec
3. Describe the chemical changes that occur in vivo during this period.
Graded Muscle Response to Increased Stimulus Intensity
4. In Activity 3, you measured the minimal (threshold) stimulus to be ________ V and the maximum stimulus to be ________ V.
5. In vivo, how do muscles receive increased stimulus intensity analogous to what was observed in Activity 3?
6. In Activity 3, you observed an increase in force proportional to the increase in stimulus intensity. How is this increase in force generated?
Multiple Stimulus
7. In Activity 4, you observed the effect of stimulating the muscle multiple times in succession with complete relaxation between stimuli. What happened to the contraction force with each stimulus? What is the phenomenon known as?
8. What chemical changes are thought to correlate to this change in vivo?
9. In Activity 5, what was the effect of increasing the frequency of stimulations?
10. How do wave summation and recruitment differ? How are they similar?
11. Explain how both wave summation and recruitment are achieved in vivo?
Summation is achieved by the nervous system increases firing rate of motor neurons. Recruitment is caused by neural activation of increasingly large numbers of motor units serving the muscle.
12. In Activity 6, how were you able to achieve smooth contractions at a given force level?
13. In Activity 6, the stimulus intensity to produce a smooth force of 2 gm was _________V and the intensity to produce a 3 gm force was _________V.
14. In Activity 7, you observed the effects of muscle fatigue. Name 4 physiologic causes that could contribute to muscle fatigue.
15. Why does a brief pause in stimulus result in prolonged muscle contraction over constant stimuli?
Quick Reply
