1. Do Now: What do you think muscles are made of?

2. Key Vocabulary Actin Myosin Microfibril Sarcomere Intercalated disc Nucleus Striation

3. Muscle tissues  Tissue in the body that can contract  Function to produce force and cause motion  Three types  Skeletal  Cardiac  Smooth

4. Voluntary/Involuntary Muscles Voluntary: occurs with thought  Running, walking, writing Involuntary: occurs with no thought  Breathing, digesting food, blinking

5. 2 Types of Skeletal Muscle Fibers Slow twitch and Fast twitch Slow twitch fibers contract for long periods of time but with little force Fast twitch fibers contract quickly and powerfully but fatigue very rapidly Both have:  Many nuclei  Are striated

7. What helps our muscles contract? In skeletal muscle tissue… Myofibrils: found in muscle, helps contraction to occur so movement can happen Sarcomeres: give muscles the striated or “lined” appearance A muscle cell from the bicep may contain over 100,000 sarcomeres

9. Smooth Muscle Tissue Has actin and myosin in it! Is involuntary Muscles controlled ONLY by the brain  Meaning that you do not think about it for muscle movement to happen  1) smooth 2) have few nuclei 3) non-branching  Ex. When your pupils contract

10. What is actin? Actin: participates in many important cellular functions Myosin: protein that works with actin to produce-  Muscle contraction  Cell movement  Cell division and organelle movement  Cell shape

11. Cardiac Muscle Tissue Type of involuntary, striated muscle (lined) found in the walls of heart Contraction- it pushes blood into the heart and through the blood vessels High number of nuclei High number of mitochondria  Why?

12. What is an intercalated disc? An intercalated disc is a double membrane separating cells in cardiac muscle fibers. Support synchronized contraction of cardiac tissue.

13. Construct a three way Venn Diagram Compare the Cardiac, Skeletal, and Smooth Muscle Types Smooth Cardiac Skeletal

14. You Do! Answer the following: 1) Is breathing an involuntary or voluntary activity? Why? 2) Which type of muscle tissue has:  High amount of nuclei?  Striations?  High amount of mitochondria?