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

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

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

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

Parts of the Muscle System

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)

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!

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

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)

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

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).

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.

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.

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.

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

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

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.

Animation: Muscles & joints http://www.freezeray.com/flashFiles/antagonisticPair.htm http://www.midsouthorthopedics.com/education.htm http://www.freezeray.com/flashFiles/hipJoint.htm http://choroknamu.com/tt/site/db/board/om_gungol/upload /1_10000/1692/is_en_pt_knee.swf

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

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.

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

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.

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

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

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

Electron Micrograph of a muscle fibre cell.

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

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

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.

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

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

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

Sliding Filament Theory Overview http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter10/animation__sarcomere_contraction.html Detail https://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter10/animation__myofilament_contraction.html Context http://highered.mheducation.com/sites/0072495855/student_view0/chapter10/animation__action_potentials_and_muscle_contraction.html 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

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

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

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

Banding pattern of actin & myosin filaments on a electron micrographs

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

Banding Pattern of Muscle Cells

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

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. 11.11 – you must be able to explain this process

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

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.

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.

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

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

Actin Filament Contracted vs. Relaxed Muscle

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.

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.

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.

Electron micrographs of muscle fibre contraction.

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.

Muscle Contraction Animations http://brookscole.cengage.com/chemistry_d/templates/student _resources/shared_resources/animations/muscles/muscles.ht ml http://media.pearsoncmg.com/bc/bc_campbell_biology_6/cipl/i ns/49/HTML/source/71.html http://highered.mcgraw- hill.com/sites/0072495855/student_view0/chapter10/animatio n__action_potentials_and_muscle_contraction.html http://www.lab.anhb.uwa.edu.au/mb140/corepages/muscle/m uscle.htm#CONTRACT http://www.sumanasinc.com/webcontent/animations/content/ muscle.html

Muscle Contraction tutorial https://www.youtube.com/watch?v=zopoN2i7ALQ

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