1. Levers

2. Synovial Joints:
Fluid-filled cavity – synovial fluid
Fluid is secreted by (1) synovial membrane, (2) articular cartilage and (3) “plasma”
“Weeping lubrication”
Bursae are separate, but have similar fluid

3. Synovial Joints:
This is a DIAGRAM
Actual cavity is really thin “Weeping lubrication”

4. Medial AND Lateral meniscus

10. Bones as levers

11. Just a Note This is NOT about physics
It’s about WHY bones are they way they are
Bones-joint ARE levers
Math/physics is just a TOOL to help describe the way they work

12. This unit is exploratory
This unit is exploratory. I provide essential background; you do the critical thinking!

13. Before We’re Done
Look at skeletons and draw conclusions about their purposes
Describe limbs have changed in adaptation to different niches
Tremendous diversity from a common platform

14. Homology

15. Lever
Effort
Resistance
Fulcrum

16. Fulcrum in the ‘middle’
Resistance in ‘middle’
Effort in ‘middle’

17. F R E

18. Class 3
Class 1

19. Class 1
Class 3

20. Class 2

21. Power vs.

22. Speed

23. Mechanical advantage = Deffort / Dresistance

24. Mechanical advantage = Deffort / Dresistance

25. It’s only a model…

26. Distance resistance moved
It’s only a model…
Model
Effort Arm
Resistance Arm
Force needed to hold 100 g
Distance Effort moved
Distance resistance moved

27. Class 3

28. Fulcrum Effort Resistance Fulcrum is the stand
Effort is the spring scale
Resistance is the weight

29. Fulcrum Effort Resistance
Measure distance from elbow to where biceps attaches and place spring at this distance
Measure distance from elbow to middle of palm and place weight at this distance

30. Class 3

31. Fulcrum Effort Resistance
Lift mass so it is parallel to table and record FORCE to hold if parallel
How far did the effort MOVE?
The resistance MOVE?
Fill in table

32. Fulcrum Effort Resistance
Move effort toward resistance and measure again
Two more times
What do your data indicate? Ratio? Pattern?

33. Work On
Obj 1-5

34. Mechanical Advantage What does MA tell you?
Diagram a lever, enter distances
Work it out
How about flexing your elbow?