10. Skeletal Muscles Flashcards
What is Epimyisum?
Fasica that envelopes the entire muscle belly
What is Perimysium?
Fasica that envelopes bundles of muscle fibres (a fasicle)
What is Endomysium?
Fascia that envelopes single muscle fibre cells
What is the MT junction?
When mysium layers converge to form the fibrous/dense tendon.
What is Periosteum?
Covers the bone and is continues with the tendon
What interacts and how, to allow muscles to contract?
Myosin heads from the thick filaments bind to the thin filaments, pulling them toward the sacromere.
This process is fueled by ATP!
What myofilaments interact in ‘sliding filament theory’?
Actin and Myosin myofilaments
What is a sacromere?
The smallest functional contractile unit of a myofibirl
What is the watery structure in which the cell apparatus floats and what is the name of it in skeletal muscles?
Cytoplasm
Sacroplasm
What energy systems do Type 1 Type 2a Type2b ..fibres use?
Type 1 - Aerobic
Type 2a - Mixed
Type2b - Anaerobic
The most common exercises involve isotonic contractions.
What is an isotonic action? and what are the 2 types?
Where the muscle contracts and there is a change in length of a muscle
Concentric and Eccentric.
What is a concentric/eccentric contraction?
Concentric - contracts and shortens in length. Origin and insertion move towards eachother (joint angle decreases)
Eccentric - contracts and increases in length. Origin and insertion move further apart (joint angle increases)
What is an isometric contraction?
No change in length as force is equal
What is an isokinetic contraction?
Muscles contract and maintains constant force and speed throughout. (Usually computerised equipment)
What is an..
Agonist/Antagonist
Synergist/Fixator?
Agonist - prime mover
Antagonist - opposite muscle that is dialled down
Synergist - assist the movement
Fixator - make moving joint stable
What is the name of a motor neurone that is connected to a number of muscle cells?
A motor unit (think movement unit!)
A motor nerve (neurone) doesn’t stimulate a whole muscle, how does it work then?
Stimulates only a number of muscle fibres within the muscle
Slow-twitch motor neurones consist of a ___ number of fibres, whilst fast-twitch motor units are ___, consisting of___ fibres
Slow-twitch motor neurones consist of a small number of fibres, whilst fast-twitch motor units are large consisting of many fibres
What is the All or Nothing principle?
Individual muscle fibres of a motro unit will contract to their fullest extent or not contract at all.
How are we able to sustain contractions for a long time?
Asynchronous firing of motor units (firing at different times)
What is muscle tone?
At a given time, some muscle fibres are contracting whilst others relax to tighten the muscle, however not enough contracting to cause movement
What is muscle tone necessary for?
Maintaining posture
What is force and tension of a contraction graded by?
Amount of motor units recruited
Apart from more motor units and more muscle tissue, how else can we get stronger?
Synchronising units to work more effectively - inter and intra muscle coordination (this comes from exercising)
