Lab 2 Discussion Questions

Question 1

Define threshold.

Answer 1

Lowest voltage that produces an observable twitch

Question 2

Threshold in a skeletal muscle vs. in a neuron?

Answer 2

• Skeletal muscle: needs to be depolarized from -90 to -50
  
  • Membran potential = -90 mV
  • Threshold voltage for AP = -50 mV
• Motor neuron: needs to be depolarized from -70 to -55
  
  • Membrane potential = -70 mV
  • Threshold voltage for AP = -55 mV

Question 3

What is tubocurare? Effects on muscle contraction over time?

Answer 3

A competitive inhibitor of nAchR

• Over time w/ continued stimulation, the muscle contractions would decrease then eventually return to normal