1. Movement
Topic 11.2

2. Assessment Statements
11.2 U1 Bones and exoskeletons provide anchorage for muscles and act as levers.
11.2 U2 Synovial joints allow certain movements but not others.
11.2 S2 Annotation of a diagram of the human elbow.
11.2 U3 Movement of the body requires muscles to work in antagonistic pairs.
11.2 A1 Antagonistic pairs of muscles in an insect leg.

3. Role of bones and Exoskeleton
anchorage
leverage
Pictures taken from
Background 206 bones in human body.
Exoskeleton
Endoskeleton

5. Leverage Bones act as levers
A lever is a rigid rod that rotates around a fixed point (fulcrum)
effort
Force applied to the lever is called effort
Force that resists motion is called the load.
lever
fulcrum

6. Levers in our body Joints act as fulcrums L E E

7. Synovial joints

8. Movements of joints
Rotation

9. AnTagonistic Pairs
Grasshopper leg

10. Assessment Statements
11.2 U4 Skeletal muscle fibers are multinucleate and contain specialized endoplasmic reticulum.
11.2 U5 Muscle fibers contain many myofibrils.
11.2 U6 Each myofibril is made up of contractile sarcomeres.
11.2 U7 The contraction of the skeletal muscle is achieved by the sliding of actin and myosin filaments.
11.2 U8 ATP hydrolysis and cross bridge formation are necessary for the filaments to slide.
11.2 U9 Calcium ions and the proteins tropomyosin and troponin control muscle contractions.
11.2 S3 Drawing labeled diagrams of the structure of a sarcomere.
11.2 S4 Analysis of electron micrographs to find the state of contraction of muscle fibers.

11. Skeletal Muscle

12. Skeletal Muscle Muscle tissue is made of muscle fibers
A muscle fiber is a large cell that contains many nuclei
Inside each muscle fiber are numerous myofibrils
Each myofibril is surrounded by a special endoplasmic reticulum called a sarcoplasmic reticulum.
Between myofibrils many mitochondria are found
Each myofibril is composed of repeating units called sarcomeres.
Each sarcomere is composed of actin and myosin filaments.
----- Meeting Notes (1/13/15 13:56) -----
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13. Skeletal Muscle Sarcolema = plasma membrane Sarcoplasmic
Reticulum = Endoplasmic Reticulum
goes around every myofibril
Stores calcium

14. Muscle fibers contain myofibrils
Screen Shot myofibril taken from Biology Course Companion by Allott & Mindorff page 480
Screen Shot of sarcomere & electromicrograph taken from Biology 9th Edition by Campbell & Reese p 1104
Actin ( thin filaments)
Myosin (thick filaments)
tutorial on sarcomere components

15. sarcomere
Screen Shot taken from Biology Course Companion by Allott & Mindorff page 481

16. How does skeletal muscle contract?
Sliding Filament Hypothesis:
(1950 – H. Huxley & J. Hanson – London)
If muscle fibers slide then band pattern should change during contraction.
Light bands would become shorter
Sarcomere would become shorter
Dark bands would stay the same length

17. Relaxed and Contracted muscle
The size of the light area indicates contracting or relaxing
Screen Shot taken from Biology Course Companion by Allott & Mindorff page 482

18. Sliding filament theory:
 Myosin has side branches with heads that create a bridge to the actin filament
ATP binds to the myosin head breaking the bridge and changing the head position releasing it from the actin
The ATP hydrolyzes into ADP & Phosphate. This causes the head to attach to the actin at a specific binding site
As the ADP and phosphate are released the head bends & the actin filament is pulled toward the center

19. Sliding filament theory:
Screen Shot taken from Biology Course Companion by Allott & Mindorff page 483

20. Role of Calcium Calcium is very important in the contraction process.
The influx of Ca+ is stimulated by the nerve impulse
The sarcoplasmic reticulum releases Ca+
An influx of Ca+ causes opening of myosin binding sites on the actin filament.
This allows contraction to occur.
When Ca+ concentration decreases the binding sites close and the muscle relaxes
Screen Shot taken from Biology Course Companion by Allott & Mindorff page 483

21. animation of the actin myosin mechanism to create movement
How movement Occurs
animation of the actin myosin mechanism to create movement

22. How Movement Occurs: Watch the animation from the Campbell CD
Screen shot taken from Campbell CD
Watch the animation from the Campbell CD
on Muscle Contraction

23. How movement Occurs
Click the link below to watch this simulation of how a muscle works.
Muscle Contraction simulation