2.2.4 HUMAN BODY SYSTEMS

1. Compare the reaction times for voluntary vs. involuntary activation of the quadriceps muscle. What might account for the observed differences in reaction times? Outline what has to occur in the body for each reaction to occur. Refer to your drawing from Step 24. Information from the flow chart you created in Activity 2.2.1 might also be helpful. The involuntary activation of the quadriceps muscle was faster than voluntary time; the reason could be that when you had to hear the sound for the voluntary activation you had to process the sound than process kicking. This would take longer than automatically kicking with the involuntary activation. In the body an impulse nerve signal had to be sent to the object reacting in this case kicking your leg.
2. How does your reaction time to the voluntary action of your quadriceps compare with your reaction time to the simple reaction task in Project 2.2.3? The task in this lab involved hearing a sound and reacting with your foot. The task in Project 2.2.3 involved seeing a signal and reacting with your finger. What do reaction times tell you about how these signals are processed? The two reaction times compare by both processing information than reacting either with your finger or with kicking your foot. They both were pretty close times because you are doing close to the same thing.
3. Assume the speed of a nerve impulse is 100 m/s. How does this compare to the speed of electricity in a copper wire (approximately 3.00 x 108 m/s)? What does this tell you about the flow of electrons in a wire compared to the movement of ions in a membrane? Electricity in a copper wire is faster than nerve impulse, this could be because an atom is bigger than an electron, and since electrons are smaller they can get through faster. In the wire there is just electrons flowing but in the nerve membrane there are proteins opening and closing which makes the nerve impulses move slower.
4. What do you think is the evolutionary