The Musculoskeletal System

1. The Musculoskeletal System Unit 7 – Mr. Mundy

2. Do Now – March 9th • Write down HW assignment in your Agenda • Take out a sheet of lined paper and a pen/pencil • Exam will begin shortly

3. What is the Musculoskeletal System? • The hard structures within our bodies are part of the skeletal system. • The Skeletal System provides support, protection, and movement for our bodies. • Press down on your wrist and you will feel bones and muscles.

4. What is the Musculoskeletal System? • A bone is a hard tissue made mostly of cells, collagen, and calcium. • Collagen is a protein that forms strong fibers in the bone. • Calcium is a mineral that adds strength to the collagen fibers.

5. What is the Musculoskeletal system? • The human body has over 200 bones that make up the skeleton. • Diets rich in calcium and Vitamin D help to maintain strong teeth and bones.

6. Functions of the Skeletal System • Bones in the skeletal are not all smooth, have different sizes, rough spots, pits, and holes where blood vessels and nerves enter and leave. • The bones in our bodies have blood vessels and nerves to deliver nutrients and signals. • This is why breaking a bone is SO PAINFUL!

7. Functions of the Skeletal System

8. Stop & Check • Write 2 things that you have just learned in this lesson so far. • 1._________________________________________________________________________________________________________________________ • 2._________________________________________________________________________________________________________________________

9. Bones Connect At Joints • Because bones are hard, they cannot bend. • However, our bodies can bend, twist, and spin. • Soft tissue called joints, holds two bones together.

10. Ligaments connect bones. • They are similar to a strong rubber-band because they stretch when we move. • Cartilage is a strong, yet flexible tissue that reduces friction and increases flexibility in our bones.

11. Try twisting your LOWER ARM without moving your upper arm! • Can you do the same with your leg? • The structure of the joint determines its movement.

12. Types of Joints

14. The Muscular System • Muscles are parts of the body that help our bodies move. • Muscle: is a tissue made of long cells that contract • There are more than 620 muscles in the human body.

15. The Muscular System • Muscles are made of bundles of muscle cells called muscle fibers. • Muscle fibers contain hundreds of nuclei and mitochondria • Muscle fibers are arranged length-wise and usually overlap other muscle fibers.

16. The Muscular System • Since Muscle fibers overlap each other, during muscle contractions the filaments move closer to each other. • When muscle fibers contract, the fibers become shorter. • Contraction is a shortening of muscle fibers in the body.

17. Muscle Contractions • What do you think makes your muscles contract? <write your response below>

18. Muscle Contractions • Muscle cells have nerve cells that start a chemical reaction in the muscle cell. • This chemical reaction causes muscle fibers to shorten and the muscle will contract. • Muscles require lots of energy and oxygen to contract.

19. Review… • Recall that cells form tissues, tissues form organs, organs form organ systems, and organ systems form an organism. • Muscles work the same way! • Muscle cells form tissue. There are 3 different types of muscle tissue in our bodies

20. Types of Muscle

22. Interactions of the Musculo-skeletal System • Our bones alone cannot move our bodies. • Similarly, muscle contraction is only part of movement • In order for us to move, the muscular system must work with the skeletal system. • Our skeleton provides support for our muscles

23. How Do You Move? • Usually, a muscle is connected to at least 2 different bones. • Tendons: connect bones to muscles • Cartilage and ligaments are 2 other types of connective tissue.

24. Opposing Muscle Groups • The bicep muscle causes your arm to bend. • Flexion is the bending of a limb that decreases the angle between the bones of a limb. • Just think… when someone asks you “flex” your arms, you make your arm bend!

25. Review… • What type of muscle do we use in our arm? (voluntary? Involuntary? Cardiac?) • Also, are the muscles in our arm shortening? Or becoming longer when we flex our biceps?

26. Opposing Muscle Groups • Muscle can contract and become shorter, but they CANNOT actively lengthen. • Extension is the straightening of a limb. • When you straighten your limb, the angle of between the bone increases.

27. Opposing Muscle Groups • Arrangement of muscles is often in opposing groups • This means that as one muscle flexes, the other is relaxing. • Example: Your Bicep/Tricep