Lab 3

Question 1

What is the graph measuring?

Answer 1

• The response of the muscle/force of contraction
• increasing over time due to increased intensity of stimulus

Question 2

What did this lab demonstrate?

Answer 2

• recruitment - as you increase the stimulus, you recruit more motor neurons

Question 3

What did the graph with sharp points at the bottom indicate

Answer 3

• indicates the increased speed of the stimulus
• shows temporal summation

Question 4

Tetanus

Answer 4

all motor neurons are summating together at a large level
- unfused tetanus - shows a relaxation phase btwn stimuli
- fused tetanus - no relaxation phase btwn stimuli
- controlled by recruitment and regulating the frequency of APs

Question 5

Pseudo fatigue

Answer 5

nervous system inhibits the degree of the activation of muscles

Question 6

Antagonist muscles

Answer 6

a contraction of one muscle stretches or elongates, and the other retracts or flexes

Question 7

Twitch

Answer 7

• activation of contractile proteins
• minimal unit of muscle contraction

Question 8

Recruitment

Answer 8

• adjusting the number of motor axons firing, thus controlling the number of twitching muscle fibers

Question 9

At stimulation intervals greater than 200 ms, what happens to intracellular Ca2+?

Answer 9

restored to baseline levels btwn APs, and the contraction consists of separate twitches

Question 10

At stimulation levels btwn 200 and 75 ms, what happens?

Answer 10

• Ca2+ is still above baseline levels, meaning that the muscle fiber has not relaxed, and the next contraction is stronger than normal
• summation