Download 11.2 Movement

11.2: Movement
Crash Course video:
https://www.youtu
be.com/watch?v=j
qy0i1KXUO4
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
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.
Functions include:
1.
2.
3.
4.
5.
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.
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
LE 49-27
Human
Grasshopper
Extensor
muscle
relaxes
Biceps
contracts
Biceps
relaxes
Triceps
contracts
Flexor
muscle
contracts
Forearm
flexes
Triceps
relaxes
Tibia
flexes
Extensor
muscle
contracts
Forearm
extends
Tibia
extends
Flexor
muscle
relaxes
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
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
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
The sacromere
Actin
Thin filaments (8nm
diameter)
Contains myosin-binding
sites
Form helical structures
Regulatory proteins:
tropomyosin & troponin
Myosin
Thick filaments (16nm
diameter)
Myosin heads with actinbinding sites
Common shaft like
structure
Heads also known as
cross-bridges, ATP
binding sites & ATPase
enzyme
Relaxed or contracted?
Overview
http://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter
10/animation__sarcomere_contraction.html
Detail
https://highered.mcgrawhill.com/sites/0072495855/student_view0/chapter
10/animation__myofilament_contraction.html
Context
http://highered.mheducation.com/sites/007249585
5/student_view0/chapter10/animation__action_pot
entials_and_muscle_contraction.html
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
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
1. Myosin heads contain ATPase (splits ATP releasing energy)
2. Myosin heads, bind to myosin binding sites on actin (tropomysin –
protein)
3. Myosin-actin cross bridge rotate towards centre of sarcomere
4. ATP binds to myosin head, detaching myosin from actin
5. Calcium ion levels fall (if no new action potential). Troponin-tropomyosin
complex returns to normal position, blocking myosin binding sites.
6. Muscle is now relaxed
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.mcgrawhill.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
Joint vocabulary
Flexion
Decrease in angle between connecting
bones
Extension
Increase in angle between connecting
bones
Abduction
Bone moves away from body midline
Adduction
Bone moves towards body
midline
Circumduction Distal (far end) of limb moves in a circle
Rotation
Bone revolves around longitudinal axis