1. Crash Course video: https://www.youtube.com/watch?v=jqy0i1KXUO4
11.2: Movement
Crash Course video:

2. Muscles & Movement Intro
A mammalian skeleton has more than 200 bones
Some are fused; others are connected at joints by ligaments that allow freedom of movement

4. Bones & exoskeletons
Bones and exoskeletons provide anchorage for muscles and act as levers.
Exoskeletons = external
Exoskeletons are often malted as the organism grows

5. Human Movement
Human movement is produced by the skeletal acting as simple lever machines

6. Parts of the Muscle System

8. Bones are organs because they contain different tissues
Bones are organs because they contain different tissues. Functions include:
Support the body
Blood cells form in bone marrow
Levers
Protection
Storage of minerals (Ca, P)

9. 1st, 2nd & 3rd class levers
Diagram pg. 477, shows the effort force, fulcrum and resultant force at three locations within the body.
In order to achieve these movements, muscles will work as pairs of antagonistic muscles.
See fig. 3, page 477.
Humans are not the only organism which uses antagonistic muscles – grasshopper legs!

12. The elbow joint
Pg. 478 draw and label this diagram from memory

13. The Elbow Joint Joint part Function Cartilage
Reduces friction, absorbs compression
Synovial fluid
Lubricates, provides nutrients to cartilage cells
Joint capsule
Surrounds joint, unites connecting bones
Tendons
Attach muscles to bone
Ligaments
Connect bone to bone
Biceps muscle
Contracts so arm can bend (flexion)
Triceps muscle
Contracts so arm can straighten (extension)
Humerus
Lever, anchoring muscles
Radius
Lever, biceps muscle
Ulna
Lever, triceps muscle
Elbow is a synovial joint because it has synovial fluid. Similar to the knee. Moves freely (diarthrotic joints)

14. Human Grasshopper Extensor muscle Biceps relaxes contracts Tibia
flexes
Flexor
muscle
contracts
Forearm
flexes
Triceps
relaxes
Biceps
relaxes
Extensor
muscle
contracts
Tibia
extends
Forearm
extends
Flexor
muscle
relaxes
Triceps
contracts

15. Joint structure and antagonistic muscle pairs (example: Elbow Joint)
A. Humerus (upper arm) bone.
B. Synovial membrane that encloses the joint capsule and produces synovial fluid.
C. Synovial fluid (reduces friction and absorbs pressure).

16. Joint structure and antagonistic muscle pairs (example: Elbow Joint)
D. Ulna (radius) the levers in the flexion and extension of the arm.
E. Cartilage (red) living tissue that reduces the friction at joints.
F. Ligaments that connect bone to bone and produce stability at the joint.

17. Antagonistic Pairs (example: Elbow Joint)
To produce movement at a joint m
uscles work in pairs.
Muscles can only actively contract and shorten.
They cannot actively lengthen.

18. Antagonistic Pairs (example: Elbow Joint)
One muscles bends the limb at the joint (flexor) which in the elbow is the biceps.
One muscles straightens the limb at the joint (extensor) which in the elbow is the triceps.

19. Elbow joint structure & function
1. Humerus forms the shoulder joint also the origin for each of the two biceps tendons 2. Biceps (flexor) muscle provides force for an arm flexion (bending). As the main muscle it is known as the agonist. 3. Biceps insertion on the radius of the forearm

20. Elbow joint structure & function
4. Elbow joint which is the pivot for arm movement
5. Ulna bone one of two levers of the forearm

21. Elbow joint Structure & Function
6. Triceps muscle is the extensor whose contraction straightens the arm.
7. Elbow joint which is also the pivot (fulcrum)for this movement.

22. Animation: Muscles & joints
/1_10000/1692/is_en_pt_knee.swf

23. Pg. 479, stand up and act out these movements to show the range of movements possible due to the synovial joint.
Knee = hinge, sometimes pivot
Hip = balland sockeet, greater range of movements

24. Muscles
Tendons – Bones and muscles are connected via non-elastic structures called tendons.
1. Tendon connecting muscle to bone. These are non-elastic structures which transmit the contractile force to the bond.
2. The muscle is surrounded by a membrane which forms the tendons at its ends.

25. Muscle Fibres A skeletal muscle consists of a bundle of muscle fibres.
A muscle fibre consists of long multinucleate cells.

26. Muscle bundle which contains a number of muscle cells The plasma membrane of a muscle cell is called the sarcolemma and the membrane reticulum is called the sarcoplasmic reticulum.

27. Ultrastructure of a skeletal muscle
Skeletal muscles consist of many muscle fibres cells.
Muscle fibre consist of many parallel myofibril within a plasma membrane called a sarcolemma

28. Ultrastructure of a skeletal muscle
The cytoplasm of the cell contains many mitochondria.

29. Ultrastructure of a skeletal muscle
The cell membrane (sarcolemma) folds inside the cell forming a transverse tubular endoplasmic reticulum called the sarcoplasmic reticulum

30. Electron Micrograph of a muscle fibre cell.

31. Muscle Fibre Cell
There are many parallel protein structures inside called myofibrils.
Myofibrils are combinations of two filaments of protein called actin and myosin.

33. Types of muscle Skeletal/striated Cardiac Smooth/non-striated
Skeletal muscles are used to move the body, they are attached to the bone.
A single plasma membrane surrounds each muscle cell (called sarcolemma) muscle cells are longer than most other cells.
Endoplasmic reticulum (sacroplasmic reticulum) connects muscle fibres and allows the cells to contract at the same time. Muscle cells contain many mitochondria.
Cardiac
Smooth/non-striated

34. Myofibrils are made of contractile sacromeres
Striated muscle cells have multiple nuclei, within the sarcolemma region.
Cytoplasm of muscle cells is called the sarcoplasm – many glycosomes and lots of myoglobin
Sarcoplasmic reticulum membranous sacs, surround myofibrils
Myofibrils, rod like. Run length of the cell. Able to contract. (see above)
Myofibrils are made of contractile sacromeres
Sarcolemma region is just inside the plasma membrane, transverse (T tubules) penetrate the inside of the cell from the sarcolemma.
Glycosomes = glycogen store
Myoglobin = red-coloured protein
Myofibrils = rod shaped, parallel to each other, run length of the cell. Reason for striated muscle appearing banded. Mitochondria between the myofibres.

36. The sacromere Draw and label the diagram of a sacromere.
One sacromere is the space between two Z lines of a myofibril

39. Thin filaments (8nm diameter) Thick filaments (16nm diameter)
Actin
Myosin
Thin filaments (8nm diameter)
Thick filaments (16nm diameter)
Contains myosin-binding sites
Myosin heads with actin-binding sites
Form helical structures
Common shaft like structure
Regulatory proteins: tropomyosin & troponin
Heads also known as cross-bridges, ATP binding sites & ATPase enzyme
Comparing the two contractile proteins – copied from pg. 297

40. Relaxed or contracted?
Skeletal muscles contract when actin and myosin filaments slide.

41. Sliding Filament Theory
Overview
Detail
Context
Actin myofilaments slide over the myosin – shortening the sarcomere. When many sarcomeres shortening at the same time muscles can create movements.
Theory proposed by Prof. Hugh Huxley 1954

42. Actin & Myosin
Actin in muscles cells consist of two strands thin filaments and one strand of regulatory protein called tropomyosin.

43. Actin & Myosin Myosin are staggered arrays of thick filaments
Myosin molecules have bulbous heads with protrude from the filament. These bulbous head will bond to binding sites on the actin filament

44. Actin & Myosin
The filaments of actin and myosin overlap to give a distinct banding pattern when seen with an electron microscope.

45. Banding pattern of actin & myosin filaments on a electron micrographs

46. Banding Pattern of muscle fibre cells
Skeletal muscle are called striated muscle because of this banding pattern
Banding is cause by regular arrangement of actin and myosin that create a pattern of light and dark bands
Each unit is a sarcomere (cell membrane), bordered by Z lines

47. Banding Pattern of Muscle Cells

48. The role of ATP
Use this diagram to explain the role of ATP in muscle contraction

49. Acetylcholine binds to sarcolemma
The steps
When action potential reaches neuromuscular junction acetylcholine is released
Acetylcholine binds to sarcolemma
Sodium enters post synapse (sarcolemma ion channels open)
Muscle action potential
(Acetylcholinase breaksdown acetylcholine)
Muscle action potential moves through T tubules, causing calcium ions to be released.
Calcium ions flood into sarcoplasm, and bind with troponin on the actin myofilaments – exposing myosin-binding sites
Myosin heads contain ATPase (splits ATP releasing energy)
Myosin heads, bind to myosin binding sites on actin (tropomysin – protein)
Myosin-actin cross bridge rotate towards centre of sarcomere
ATP binds to myosin head, detaching myosin from actin
Calcium ion levels fall (if no new action potential). Troponin-tropomyosin complex returns to normal position, blocking myosin binding sites.
Muscle is now relaxed
Like every other response in the body, muscle movement is controlled by nerves.
Sarcolemma – post synapse in muscle fibre
Pg. 298, fig – you must be able to explain this process

50. You must be able to compare electron micrographs of muscles in three states – relaxed, fully contracted & partially contracted.
Pg. 482, fig. 18

51. Mechanism of muscle contraction
1. An action potential arrives at the end of a motor neuron, at the neuromuscular junction.
2. This causes the release of the neurotransmitter acetylcholine.

52. Mechanism of muscle contraction
3 This initiates an action potential in the muscle cell membrane.
4. This action potential is carried quickly throughout the large muscle cell by invaginations in the cell membrane called T-tubules.

53. Mechanism of muscle contraction
5. The action potential causes the sarcoplasmic reticulum (large membrane vesicles) to release its store of calcium into the myofibrils.

54. For a muscle fiber to contract, myosin-binding sites on the actin fibre must be uncovered
This occurs when calcium ions (Ca2+) bind to a set of regulatory proteins, the troponin complex – making the binding sites exposed

55. Actin Filament Contracted vs. Relaxed Muscle

57. This exposed myosin-binding sites bond with the bulbous heads (cross bridge) of myosin filament.
Cross bridges include an ATPase enzyme which can oxidise ATP and release energy.

58. The cross bridge swings out from the myosin (thick filament) and attaches to the actin (thin filament).
The cross bridge (bulbous head) changes shape and rotates through 45°, causing the filaments to slide. The energy from ATP is used for this “power stroke” step.

59. A new ATP molecule binds to myosin and the cross bridge detaches from the Actin (thin filament).
The cross bridge changes back to its original shape, while detached (so as not to push the filaments back again).
It is now ready to start a new cycle, but further along the thin filament.

61. Electron micrographs of muscle fibre contraction.

62. Electron micrographs of muscle fibre contraction.
If electron micrographs of a relaxed and contracted myofibril are compared it can be seen that:
These show that each sarcomere gets shorter (Z-Z) when the muscle contracts, so the whole muscle gets shorter.
But the dark band, which represents the thick filament, does not change in length.
This shows that the filaments don’t contract themselves, but instead they slide past each other.

63. Muscle Contraction Animations
_resources/shared_resources/animations/muscles/muscles.ht ml
ns/49/HTML/source/71.html
hill.com/sites/ /student_view0/chapter10/animatio n__action_potentials_and_muscle_contraction.html
uscle.htm#CONTRACT
muscle.html

64. Muscle Contraction tutorial

65. Decrease in angle between connecting bones
Joint vocabulary
Flexion
Extension
Abduction
Adduction
Circumduction
Rotation
Decrease in angle between connecting bones
Increase in angle between connecting bones
Bone moves away from body midline
Bone moves towards body midline
Definitions, pg. 294
Distal (far end) of limb moves in a circle
Bone revolves around longitudinal axis