1. Do Now: 02/20-21 What are the three types of muscle? Which skeletal muscle allows you to chew? Finish this statement: Nikki Minaj has a very large _________ muscle. She must do a lot of squats. Have your Check Your Recall Work out on your desk.

2. Last Class SWBAT explain the purpose of the muscular system and name the major skeletal muscles of the body SWBAT describe the anatomy of a skeletal muscle How did we accomplish this? Brief notes of muscle structure. Diagram of the 15 major skeletal muscles. Check Your Recall Questions 1-4

3. Nervous Tissue O Motor Neurons: nerve cells which control muscle movement O Neurotransmitters: chemicals secreted to stimulate muscle fibers to contract O Motor Units: O 1 motor neuron + the muscle fibers associated with it

4. Check Your Recall O How many different types of tissue come together to form our skeletal muscle? O List at least one example of each.

5. Skeletal Muscle Contraction is a result of actin and myosin sliding over one another, generating the force of contraction

6. Think Pair Share O What does contraction mean? O Contract your arm. O Predict: What do you think we call the opposite movement?

7. 8 Stages of Contraction O 1. Motor neuron receives an impulse O 2. Motor neuron releases the neurotransmitter acetylcholine into the gap between the neuron and the muscle O 3. The acetylcholine attaches to receptors on the muscle fiber membrane.

8. Contraction O 4. The muscle responds by releasing calcium ions into the myofibrils O 5. The calcium ions attach to the Actin and unlock the binding sites O 6. The cross-bridges from the myosin attach to the binding sites

9. Contraction O 7. The cross-bridges fire and pull the actin which shortens the sarcomere O 8. All of the shortening sarcomeres lead to a shortening (contracting) of the muscle

10. Can’t use words you don’t know… define the following O What is a sarcomere? O Actin? O Myosin? O Acetylcholine?

11. Explaining Contraction O You can do this in three ways O A flow chart O A cartoon O A paragraph You MUST include all 8 stages discussed in class, and each stage needs to be in your own STUDENT FRIENDLY words O Materials: Paper, Colored Pencils, Notes, Markers