Module 4 Flashcards
What is muscle contraction?
Force is transmitted through the tendon to move the bones through the joints in the middle, causing the muscle to contract
Where are sarcomeres located?
Myofibrils
What causes contraction?
Sarcomeres
Process of muscle contraction (myosin, discs and sarcomeres)
Actin is going to slide over the myosin to cause a contraction
-Myosin stays the same, both actin filaments slide over the top makes the muscle shorter and makes it contract
-Z disc- end and start point of sarcomeres
-Series: back to back against the back of the muscle fibre
-1 sarcomere between the X discs
Process of muscle contraction (MN)
-For muscle contraction to occur, each of our muscle fibres are contained in what is called a motor unit, in a motor unit there’s a motor neuron, engaging muscle fibres
-When we get an action potential in the MN, leads to an action potential in all of the muscle fibres, causing them to contract
-When a muscle recieves a stimulus to contract, a nerve impulse goes down through the brain, down the spinal cord, peripheral nerve and synapses on the muscle fibres
-Series of chemical reactions that causes the filaments to slide on each other, shortening the length of each sarcomere, giving us a contraction.
Neuro issue for muscle contraction
-Muscle fibres shorten and lengthen through a process of mechanochemical changes, the drive for this comes from electrical signals transmitted extremely quickly through the nerve fibres, the brain sets the intensity of the muscle contraction based on the need to deliever an appropriate amount of force
-More force= more muscle fibres recruited
——-Damage to the brain is a mismatch of force (little/too much) -Weakness or over shoot
Relationship of position to muscle force
(No we are not able to generate the same amt of force)
-Mid-range of the muscles length (amount of force we can generate in a bicep curl, when we are fully straightened or bent we can produce that much force (around 90))
-Optimum crossover between the actin and myosin filaments (maximum tension within that muscle)
-Isometric strength testing- position of the joint the same in both sides and position where they might need that strength- what position brings up their pain, we should make this component stronger
Contractile response of muscle over range of contraction
The contractile response of muscle is not the same over the range of its contraction
-The velocity at which a muscle is required to contract affects the amount of force it can generate
-Muscles are designed and adapt to suit the demands they most often experience (length shape, optimum, range etc)
Tailoring muscle contractions to patient needs
-What we need to think about the type of contraction and how we can the muscle contracting depending on what the patient needs to achieve
-Bodybuilder- powerlifing, lifting them very slowly, maximum force that is slowly
-Faster velocity- running and volleyball, jumping up to spike ball, lots of power needed and force generated quickly, training them to have an opitimal amount of power
-Normal velocity of movement- we don’t need to increase their velocity and muscle for power
-Tailing exercise prescription to needs
Non-contractile elements of the MTU
- Tendons, ligaments and
- skin
- Collagen: collagen fibre and collagen fibril
- Collagen basic building block of connective tissues
- Collgen proteins organised in a helical strucutre- very strong
- Collagen is important as its intended strength means the force developed in the muscle is transmitted effectively to the bone
- Efficient and immediete movement
Tendon needs to be stiff and rigid to transmit that force
Collagen and its role in MTU
-Joins things together as it is a connective tissue
-It is an elastic solid and its water content makes it visco elastic and speed dependent
-The arrangement of muscle fibres and collagen produce a complex mechanical structure designed to optimise energy transfer
Contractile elements
-Thin and thick filaments within each sarcomere slide over one another
-Maximum contraction force produced around 50% length
-Capable of force generation across an impulsively large range of values
-Speed of movement influences force produced and vice versa
Non-contractile elements
Provides strength and structure
-Resists stretching
-transmits contractile forces from muscle to bones, rotating joints
