Electrical Station Lab 4.1
Electrical Systems in Health Fields
Action Potentials and Muscle Contraction
PRESENTATION AND PRACTICE
In this experiment, you will use EMG to see the electrical activity in your forearm muscles.
WORK WITH THE VERNIER EMG SENSOR AND ELECTRODES, LAPTOP, LABQUEST MINI INTERFACE, HAND DYNAMOMETER, LOGGER PRO SOFTWARE AND ANSWER SHEET PROVIDED.
Refer to Experiment 18, “EMG and Muscle Fatigue” on page 18-1 of the lab manual provided at your station, called Human Physiology with Vernier. Read the introduction on page 18-1, and follow the instructions on how to perform this lab given on pages 18-2 through 18-4.
You should have your own copy of the Data tables seen on page 18-5. Record all data you collect on your copy, DO NOT write directly in the lab manual.
DO NOT answer the questions provided on pages 18-5 and 18-6 of the lab manual. You will be provided with a worksheet containing questions about your results that you will need to answer after completing the lab.
You may need help from your coach to help you set up the equipment, and you will need a partner to perform the experiment. If another student is not available, the coach can be your partner.
Application Questions – Write down your answers on your Answer Sheet.
- If you were to repeat the experiment with your other arm, do you think it would fatigue faster or slower and why?
- If you spent the next 6 weeks doing biceps curls for 15 minutes every day, your biceps muscles would get much stronger.
What differences do you think you’d find in initial firing rate (frequency) and muscle recruitment (amplitude) if you then repeated this experiment and compared it to your original graph?
Evaluation
Your lab performance will be evaluated by the criteria (standards) you will find in this project’s rubric. A rubric is simply a table that states how you will be evaluated. Your coach will use this table to report your performance.
CLICK HERE TO GO TO THE RUBRIC
Lab Review
- Your brain, spinal cord and all of the nerves in your body make up the nervous system.
- The nervous system is divided into the central nervous system (CNS) and peripheral nervous system (PNS).
- The PNS is further divided into the autonomic nervous system (involuntary), and the somatic nervous system (voluntary).
- The individual cells of the nervous system are called neurons, and nerves are made up of many neurons bundled together.
- Neurons transmit electrical signals and communicate at meeting points called synapses. Synapses can be electrical or chemical.
- There are three main types of neurons: afferent (or sensory) neurons allow us to sense information in the environment; efferent (or motor) neurons allow the brain to tell the body what to do; interneurons form connections between other neurons.
- Motor neurons communicate with muscles at a special type of synapse called a neuromuscular junction.
- A single motor neuron plus all the muscle fibers it communicates with is called a motor unit.
- Strength of muscle contraction depends on firing rate and muscle recruitment (the number of active motor units).
- Electromyography (EMG) allows us to produce a record of the electrical activity in a muscle, called an electromyogram.
- An electromyogram has two main parts: frequency (represents firing rate) and amplitude (represents muscle recruitment).
- Normally the body produces energy using oxygen, and performs aerobic contraction of the muscles.
- Heavy muscle use requires continuous energy, but when there is not enough oxygen available the muscles must resort to anaerobic contraction.
- Anaerobic muscle contraction causes acid-build up, which results in muscle fatigue.
- When a muscle fatigues, two things happen on the electromyogram: frequency decreases, and amplitude increases.
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Links to Station 4.1Modules
Lab Intro | Lab Presentation and Practice | Communications Intro| Communications Presentation and Practice| Math