Download Communication - Mrs Jones A

Starter
O Asked to cover coordinating
movement
synapses/neuromuscular
junctions ……
O JOINTS
O What key words does this bring to mind
O Whiteboards!
O GCSE!!
Learning Outcomes
O Describe how coordinated movement
requires the action of skeletal muscles
about joints – with reference to the elbow
joint.
O Compare and contrast the action of
synapses and neuromuscular junctions.
Joints and Movements
O All movement is controlled by muscles pulling on a
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joint.
Muscles can only pull therefore at least two muscles
must be used to move bones back and forth.
Muscles which work in this way are known as
antagonistic
Any muscle which contracts and causes extension of a
joint is called an extensor
The corresponding flexor muscle contracts to reverse
the movement
NB – these are also the ‘general’ terms for the
muscles found in the forearm.
The action of antagonistic
muscles
O Raise and lower your lower arm at the elbow
and FEEL/DESCRIBE what is happening in
upper arm!!!!
O Using appropriate terminology explain how
antagonistic muscles act together to raise
and lower a limb.
O Muscles can only contract and relax, therefore they
can only pull on a bone, not push it
O To produce movement, 2 muscles must act as
antagonistic pairs to move a bone to and from
different positions
O To raise a limb, the flexor contracts pulling the limb
bone up (extensor relaxed)
O To lower the limb, the extensor contracts, pulling the
limb down (flexor relaxed)
FEEL IT!!
Synovial joint structure
O Synovial joints occur where a large amount
of movement is required
Synovial joint structure
O Synovial joint: bones move in joints separated by
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a cavity filled with synovial fluid
Tendon: Joins muscle to bone, allows muscle to
power movement
Ligaments: joins bone-bone, strong, flexible,
restrict movement of joint (protection)
Cartilage: protects bones in joints, acts as shock
absorber, absorbs synovial fluid.
Synovial membrane: secretes synovial fluid
Synovial fluid: lubricant
Fibrous capsule: encloses joint
Action of muscles
O A joint is a place where two or more
bones meet.
O Synovial joints are adapted to allow
smooth movement between the bones
O The elbow is a hinge joint, allowing
movement in one plane
O Two antagonistic muscles act across the
elbow
O The biceps contract to flex the arm
O The triceps contract to extend the arm
Movement of the elbow joint
O The contraction of
the triceps muscle
lowers the arm
O extension
Movement of the elbow joint
O The contractions of
the biceps and
brachialis muscles
raises the lower arm
O flexion
Movement of the elbow joint
O In some movements,
both the muscles
contract to some
degree.
O For example, the
triceps may contract
to act as a steadying
force ensuring that
the contraction
caused by the biceps
produces a controlled
and steady movement
MINI Plenary: individually onto
whiteboards
When you contract your biceps muscle what happens to
your arm?
Flex
It holds bones together.
Ligament
When you contract your triceps what happens to your
elbow joint?
Extends
It attaches muscle to bone
Tendon
A moveable joint.
Synovial
Prevents wear and tear in the joint.
Cartilage/synovial fluid
When you straighten your leg what happens to your knee
joint?
Extends
Must be passively stretched to allow movement.
Antagonistic
Can be damaged with overuse of a joint.
Cartilage, tendon, ligament
Complete this sentence: ‘When you bend your arm your
biceps muscle is contracting and your triceps is
relaxing. The muscles are …’
Antagonistic
Neuromuscular junction
O This is a specialised synapse between the
end of a motor neurone and the muscle
fibre membrane adjacent to it
O The end of the motor neurone is often
referred to as an end plate or motor end
plate
O In pairs verbally: Compare the arrival of a
nerve impulse at a synapse to a
neuromuscular junction
Synapse
An action potential/impulse arrives at the
presynaptic knob.
The presynaptic membrane depolarises
Calcium ion channels in the membrane open.
Calcium ions enter the presynaptic knob these
cause the
Vesicles holding neurotransmitter fuse with the
presynaptic membrane.
Neurotransmitter/ acetylcholine is released into the
synaptic cleft.
Neurotransmitter diffuses across the synaptic cleft.
Neurotransmitter binds to specific receptors on the
postsynaptic membrane.
Protein channels on the postsynaptic membrane
open.
Sodium ions enter the postsynaptic neurone.
The postsynaptic membrane is depolarised.
An action potential is triggered in the postsynaptic
neurone.
Acetylcholinesterase breaks down acetylcholine
Neuromuscular junction
An action potential/impulse arrives at the
neuromuscular junction
Vesicles holding neurotransmitter fuse with the
presynaptic membrane.
Neurotransmitter diffuses across the synaptic
cleft.
Neurotransmitter binds to specific receptors on
the muscle fibre membrane (sarcolemma)
called the motor end plate
Depolarisation travels down T system tubules
This depolarisation leads to release of calcium
ions from the sarcoplasmic reticulum
The calcium ions bind to proteins in the muscle
that lead to contraction
Acetylcholinesterase breaks down
acetylcholine so muscle contraction only
occurs when impulses arrive continuously
NOW:
O Compare and contrast the action of
synapses and neuromuscular junctions
Compare and contrast the features of synapses
and neuromuscular junctions
Synapse
Neuromuscular junction
Neurone to neurone
Neurone to skeletal muscle cell
Post synaptic stimulation leads to
action potential in post synaptic
neurone: muscle/gland
Post synaptic stimulation leads to
depolarisation of sarcolemma,
muscle contraction
Excitatory/inhibitory
Always excitatory
Synaptic knob is smooth and
rounded
End plate has brushed appearance:
microvilli and is flattened up to
muscle fibre
Neurotransmitter in vesicles in
presynaptic cytoplasm
Neurotransmitter in vesicles in
presynaptic cytoplasm
Vesicles release neurotransmitter
into cleft on stimulation: synaptic
cleft
Vesicles release neurotransmitter
into cleft on stimulation:
neuromuscular cleft
Compare and contrast the features of synapses
and neuromuscular junctions
Synapse
Neuromuscular junction
Neurotransmitter diffuses across
synaptic cleft and binds to post
synaptic receptor
Neurotransmitter diffuses across
synaptic cleft and binds to post
synaptic receptor: sarcolemma
Binding of neurotransmitter results in
opening of sodium channels and
depolarisation of the post synaptic
membrane
Binding of neurotransmitter results in
opening of sodium channels and
depolarisation of the post synaptic
membrane: T-system tubules
Enzymes present to breakdown
neurotransmitter to avoid continual
stimulation of postsynaptic
membrane.
Enzymes present to breakdown
neurotransmitter to avoid continual
stimulation of postsynaptic
membrane. And muscle contraction
Exam question
O 8 marks
O QWC!