HUBS Lecture 10 Flashcards
what is a first class lever
a lever that stabilises joint position - the fulcrum is between the force and the load like a seesaw
what is a second class lever
a lever that is effective for overcoming heavy loads - the load is between the fulcrum and the force like a wheelbarrow
what is a third class lever
a lever that has a large range of movement - the force is between the fulcrum and the load like a fishing rod
what are the three ways in which muscle fibre form determines function
- length of muscle fibres
- number of muscle fibres
- arrangement of muscle fibres
what percent of their length can muscle fibres shorten to
50% of their resting length
if a large range of motion is required will muscle fibres be longer or shorter
muscle fibres will be longer - the tendon (which doesn’t contract) will be shorter or not present at all
what is tension directly proportional to
the cross sectional area (CSA) - the greater the number of fibres the greater the CSA and the greater the tension
what are the pros and cons of a parallel arrangement in muscle fibres
smaller CSA (fewer muscle fibres) but also a greater shortening
what are the pros and cons of a pennate arrangement in muscle fibres
greater CSA (more muscle fibres) but less shortening because the muscle fibres can only shorten up to half the length of the shortest fibre
where might muscle fibres be arranged parallel
in places where less strength is needed but more movement is needed
where might muscle fibres be arranged pennate
where more strength is needed and less movement is needed
what is concentric muscle action
when the tension is greater than the load so the muscle shortens - this results in a change in joint position
what is eccentric muscle action
when the tension is less than the load and so the muscle elongates because its being pulled in the opposite direction by another muscle/gravity - this results in a change in joint position
what is isometric muscle action
when the tension equals the load so there is no change in the length of the muscle and therefore no change in joint position - this still requires energy because the muscle is active
what is an agonist
the muscle that creates movement and always acts concentrically
what is an antagonist
the muscle that opposes/controls movement and always acts eccentrically
what is a stabiliser
a muscle that holds the joint still and always acts isometrically
what is a neutraliser
a muscle that stops unwanted movement and can act any way depending on what’s needed
