2. Chapter Menu Lesson 1: The Musculoskeletal System
Lesson 2: The Body and Levers
Click on a hyperlink to view the corresponding lesson.

3. 9.1 The Musculoskeletal System
bone
joint
cartilage
muscle
contraction
relaxation
tendon
flexion
extension

4. 9.1 The Musculoskeletal System
The Skeletal System
The skeletal system provides support, protection, and movement.
Bones are hard tissue made mostly of cells, collagen, and calcium.
What are the major bones in the human body?

5. Functions of the Skeletal System
9.1 The Musculoskeletal System
Functions of the Skeletal System
Bones protect the soft tissue of the brain, spinal chord, and organs.
Bones provide attachment points for muscles.
They store calcium and phosphorous for later use.
Blood cells are formed in the bone marrow in the middle of some bones.

6. Bones Connect at Joints
9.1 The Musculoskeletal System
Bones Connect at Joints
Our bodies are flexible because bones connect at joints.
Cartilage is a strong yet flexible and elastic tissue that reduces friction and increases flexibility.

7. Joints in the Human Body
9.1 The Musculoskeletal System
Bones Connect at Joints (cont.)
Joints in the Human Body

8. Joints in the Human Body
9.1 The Musculoskeletal System
Bones Connect at Joints (cont.)
Joints in the Human Body

9. The Muscular System Muscle is tissue made of long cells that contract.
9.1 The Musculoskeletal System
The Muscular System
Muscle is tissue made of long cells that contract.
Muscles are bundles of muscle cells called muscle fibers.
Small tubes in the fibers contain bundles of muscle filaments.
Muscle filaments move closer to each other during muscle contraction, and move away during muscle relaxation.

10. Types of Muscles Voluntary muscles can be controlled.
9.1 The Musculoskeletal System
Types of Muscles
Voluntary muscles can be controlled.
Involuntary muscles work without your active involvement.
The three types of muscle tissue are:
skeletal
cardiac
smooth

11. How do you move? The skeleton provides support for muscles.
9.1 The Musculoskeletal System
How do you move?
The skeleton provides support for muscles.
A muscle usually connects to at least two different bones.
Tendons connect bones to muscles and do not stretch as much as ligaments.
Flexion is the bending of a limb that decreases the angle between the bones of the limb.

12. Opposing Muscle Groups
9.1 The Musculoskeletal System
Opposing Muscle Groups
Extension is the straightening of a limb that increases the angle between the bones of the limb.
How Joints Work

13. Opposing Muscle Groups (cont.)
9.1 The Musculoskeletal System
Opposing Muscle Groups (cont.)

14. Which of the following does not make up bone tissue? A calcium B cells
9.1 The Musculoskeletal System A B C D
Which of the following does not make up bone tissue?
A calcium
B cells
C smooth tissue
D collagen
Lesson 1 Review

15. What is the term for the location where bones connect? A joints
9.1 The Musculoskeletal System A B C D
What is the term for the location where bones connect?
A joints
B tendons
C ligaments
D cartilage
Lesson 1 Review

16. A adds strength to the motion
9.1 The Musculoskeletal System A B C D
What does the slight contraction of triceps contribute to the contraction of the biceps during flexion?
A adds strength to the motion
B keeps the bicep from contracting too much
C keeps the elbow in its proper place
D makes the motion smooth and controlled
Lesson 1 Review

17. End of Lesson 1

18. 9.2 The Body and Levers lever fulcrum first-class lever
second-class lever
third-class lever
mechanical advantage

19. 9.2 The Body and Levers
What is a lever?
A lever is a simple machine made of anything rigid that pivots around a fixed point.
A fulcrum is the fixed point that a lever pivots around—the pivot point.

20. Levers Two forces act upon different parts of a lever. Effort force
9.2 The Body and Levers
Levers
Two forces act upon different parts of a lever.
Effort force
Resistance force

21. 9.2 The Body and Levers
Why use levers?
Levers are used to make difficult jobs easier—to lift heavy objects or move objects faster or farther.

22. 9.2 The Body and Levers
Levers in the Body
Third-class levers make it easier to move an object over a long distance quickly.
Your limbs contain multiple joints and therefore multiple levers.
The length of a lever affects the way your body works.

23. Levers in the Human Body
9.2 The Body and Levers
Levers in the Human Body

24. Levers in the Human Body
9.2 The Body and Levers
Levers in the Human Body

25. 9.2 The Body and Levers
Mechanical Advantage
Mechanical advantage (MA) is the ability of a machine to increase the amount of force put into the machine.

26. What determines how easy or hard it will be to use a particular lever?
9.2 The Body and Levers A B C D
What determines how easy or hard it will be to use a particular lever?
A the class of lever
B the distance between the fulcrum and the effort force
C the distance between the effort force and the resistance force
D the distance between the forces and the fulcrum
Lesson 2 Review

27. What type of lever is a wheelbarrow? A first-class B second-class
9.2 The Body and Levers A B C D
What type of lever is a wheelbarrow?
A first-class
B second-class
C third-class
D fourth-class
Lesson 2 Review

28. 9.2 The Body and Levers A B C D
What is the mechanical advantage of a lever if the effort force is 4 m from the fulcrum, and the resistance force is 8 m from the fulcrum?
A 0.5
B 1.5
C 2
D 4
Lesson 2 Review