DEM

 Activation of muscles by nerves results in the flow of ions across cell membranes  The flow of ions generates electrical activity that results in muscle contraction  An electromyogram (EMG) records the electrical activity within muscles

Muscles are attached to at least two points  Origin – attachment to a moveable bone  Insertion – attachment to an immovable bone Figure 6.12

Figure 1 In Experiment 15 the extensors of the forearm will be studied

In this experiment, you will  Obtain graphical representation of the electrical activity of a muscle.  Associate muscle activity with movement of joints.  Correlate muscle activity with injury.

 computer  electrode tabs  Vernier computer interface  ruler  Logger Pro (version 3.6)  5 lb weight (barbell)  Vernier EKG Sensor

1. Connect electrodes 2. Obtain baseline 3. Collect and record data while flexing and relaxing the extensor muscle of the forearm 4. Do # 3 with a weight (barbell) 5. Change to the flexor muscles and do the same thing.

Take notes on what you and your group are doing. One person in the group is the subject (“guinea pig”). Each person will write a lab report (later) so keep track of what is going on.

1. Data table 2. Data analysis (answers to the questions) 3. Lab Report (more instructions later on this)