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A2 Physiology. People are Awesome 2013. Sliding Filament Theory. Learning Outcomes: All demonstrate understanding of the muscle structure. Most gain understanding of the sliding filament theory through practical activity - PowerPoint PPT Presentation
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Sliding Filament Theory Learning Outcomes:
All demonstrate understanding of the muscle structure.
Most gain understanding of the sliding filament theory through practical activity
Few can apply the muscle concept and are able to lead the rest of the class in practical activity.
Muscle Structure Starter activity
Describe the structure of skeletal muscle
(4 marks)
Extension: draw a diagram to further illustrate your understanding.
Muscle Structure Starter activity
Max 2 marks:Muscles are covered in a layer of connective tissue called EpimysiumThere are bundles of fibres surrounded by another connective tissue called PerimysiumEach muscle fibre is surrounded by a connective tissue called EndomysiumMax 2 marks:Each muscle fibre contains hundreds of myofibrilsThese contain proteins responsible for muscles contraction, actin and myosin.Together they form the contractile units, the sarcomeres.
Home Work Complete exam question on Sliding filament
theory: Handout p42 Q1 & 2. Read (p36-40 AQA A2 PE)and make notes
on:
- the three types of Muscle Fibres
- describe a Motor Unit and explain how a Motor Neurone can stimulate muscle fibres.
The Sliding Filament Theory Myofibril is - the contractile unit of the
muscle. These can be divided into units called
Sarcomeres Each sarcomere contains 2 types of protein
filaments - Actin & Myosin During contraction these slide across one
another and connect or make cross bridges.
This overlapping creates a striped appearance.
Practical Activity
http://www.youtube.com/watch?v=EdHzKYDxrKc&feature=related
Pupils act out the movement of the actin and myosin filaments.
Draw and clearly label a Sarcomere
Include the following:- Myosin, Actin, Sarcomere and Z line.
Extension – add to the diagram the following:
- A band, I band and H zone
- explain what each of these are.
Sacromere during relaxed stateZ lines – mark the boundary of each sacromereA band – identifies where both actin and myosin existI band – identifies where only actin existsH zone - identifies where only myosin exsists, this disappears during contracted state.
ActinMyosin
Task 2In your own words describe the process that occurs for the sarcomere to close together. (The muscles to contract)
You can use your homework to help complete this.
Sarcomere Movement At rest the protein tropomyosin on the actin blocks
access to the myosin binding site
Step 1: These can be overcome by the release of calcium
from the sarcoplasmic reticulum – this occurs upon receiving an action potential (signal to contract).
The Ca binds to Troponin and neutralises the Tropomyosin and releases the binding sites.
Step 2: Myosin has tiny protein projections that look similar
to golf clubs, they attach to the actin.
Step 3: Each projection contains ATPase which is an
enzyme used to break down ATP. This provides the energy to bind the myosin crossbridge to the actin filament. (enables the Myosin to pull the actin inwards).
Step 4: It works like a ratchet mechanism where cross
bridges constantly attach and detach.Step 5: Once the impulse has diminished Ca+ returns to
sacroplasmic reticulum and actin returns to its resting position.