1. These two work together
Muscles and Skeleton
These two work together

2. What does your skeleton do for you?
Supports you as you stand and sit
Protects your internal organs
Allows you to move
Makes new blood cells
Stores calcium, phosphorus and fat

3. Let’s “dissect” a bone
Compact bone is on the outside (the hard stuff)

4. Spongy bone is on the inside (more porous)

5. Bone marrow is at the center
Red marrow makes blood cells
Yellow marrow stores fat

6. What do you call the places where bones connect?
joints

7. More physics: joints act like levers
You would not be able to move without these

8. What holds your bones together at joints?

9. What connects your bones and muscles?

10. Exit Questions 1. How are COMPACT BONE and SPONGY BONE different?
2. What are 2 functions of bone marrow?
3. How are ligaments and tendons different?
4. What is a joint? Give 4 examples.

11. What do muscles do?
Contract to help you move

12. Let’s “dissect” a muscle
Muscles are made up of muscle fibers

13. Muscle fibers are made up of sarcomeres

14. Sarcomeres are composed of two types of protein
Actin
Myosin

15. Here’s what happens when muscles contract!
A signal arrives from a nerve to the muscle
Calcium is released inside the muscle
(calcium is required for muscles to contract)

16. The myosin “heads” move dragging the actin with them

17. It looks like this

18. Thus, contracted muscles have shorter sarcomeres

19. Contracted sarcomere

20. When the muscle relaxes, The actin and myosin return to their normal positions

21. Cool animation

22. There are three types of muscle
1. Cardiac in your heart

23. 2. Smooth in your arteries and internal organs

24. 3. Skeletal attached to your bones

25. Only one of these is voluntary which means you have to intentionally contract it
Which one?

26. Exit Questions 1. Describe how muscles allow you to move.
2. What does voluntary mean? Involuntary?
3. Describe the three types of muscle.
4. What is a sarcomere? Which proteins make up the sarcomere, and how do they cause muscle contraction?