week 6 Flashcards
describe the sliding filament theory
- when the muscle fibre contracts the “I” band disappears.
- this is because the actin myosin will cross over each other in the “I” band regions
what are the roles od troponin and calcium during contraction (x2)
- used as part of the contraction process
-the actin and myosin are not able to form a bridge until calcium is present in the body.
what does tropomyosin do
partially covers the myosin binding site
what is the role of troponin
holds tropomyosin in blocking position
describe the role of calcium (x3)
- calcium binds to troponin
- produces changes in shape of troponin
- allows tropomyosin to move away from myosin binding sites
describe excitation ( contraction coupling) (x5)
- receive messages from the brain to contract
- depolarisation and depolarisation indicate that the message contract has arrived at the muscle cell
- the sequence of events where an action potential in sarcolemma leads to cross bridging.
- action potential in skeletal muscle completed before any signs of muscle contraction
- action potential stimulates the cytosol calcium release.
describe muscle myo plasticity (x4)
- microenvironment= cells that are not replenished, responsible for regulating the amount of protein synthesis that takes place and protein degradation
- adequate energy intake= important because it is needed in order to meet efficient protein synthesis
- neurological recruitment= helps with the amount of power or force the muscle is able to produce
- phenotype= the physical characteristics. this will affect protein synthesis adaptability.
STRUCTURAL FACTORS AFFECTING MUSCLE FUNCTION: power
power= force x velocity
- this will help determine how much power a muscle is able to produce.
STRUCTURAL FACTORS AFFECTING MUSCLE FUNCTION: shape and design of the muscle
- size in muscle makes a difference in the type of transport of work it can do .
- possible factor of muscle fibre radius= increase of muscle fibre radius may increase endurance
- the cell volume of the structural radius affects calcium release and contraction
STRUCTURAL FACTORS AFFECTING MUSCLE FUNCTION: protein composition
myosin head= different kind of proteins in them all which will determine how well they function specifically
- consists of light and heavy chains
- iso form proteins= same protein or same structure but slightly different functions to it
what are the four isoforms of the myosin heavy chain
1) type 1= the slow contracting muscle fibre
2) type 2 a= increase in velocity when they contract
3) type 2x= increase in velocity when they contract
4) type 2b= increase in velocity when contracting
define the capillary influences on muscle function
like muscle fibre radius, the number of capillaries influences diffusion distance and therefore endurance performance
what are the 3 architectural factors affecting muscle function
- influence muscle velocity
- influence muscle force
- influence muscle exertion
architectural influences on muscle velocity
the second cer will contract with same velocity that will add onto that velocity
architectural influences on muscle force
- if had a single sarcomere= each sarcomere has a specific force of contraction
- 22 to 28 newtons produced
- each sarcomere will produce the same amount of force at the same time
-
describe muscle pinnation
the deltoid is a multi pennated muscle that the fibres are angled with respect to the angle it contracts at
what are the two adaptions necessary for hypertrophy to occur
- increased protein synthesis
- increased satellite cell proliferation
describe skeletal muscle physiology in relation to plasticity and responses to exercise (x2)
- signalling proteins activate genes to produce mRNA responsible for an increased protein synthesis
- number of myonuclei determines the number of mRNA, limits the production of protein and therefore hypertrophy
what are the 2 negative regulators of hypertrophy
- my-statin may regulate muscle size and fibre number
- gene knockout in mice yielded
identify the two muscle power regulators and describe both of them
1) force regulators:
- frequency of simulation
- motor unit size and number
- position of fibre
2) velocity regulators
- fibre length
- myosin ATPase isoform
