28. Muscles and Movement Flashcards
what are the six major functions of the skeleton?
support,
movement,
protection,
production of blood cells,
storage of minerals
endocrine regulation.
what is the role of an agonist muscle and an antogonist muscle? give the answer with an example
they are opposing muscles at joints.
agonist muscle contracts (shortens) - responsible for movement
antagonist is the opposite (lenghthens)
eg in a bicep curl, the bicep is contracted and shortens while the tricep lenghthens. then the opposite occurs on the way back down
how do muscles provide movement?
muscles ONLY contract, so they move by pulling two segments together with its antagonist pair.
one muscle contracts and the other relaxes (reciprocal innervation)
what are the four functions of muscle?
contractibiliity - ability to shorten and contract
excitabilty - stimulation by nerves and hormones
extensibility - stretched beyond normal resting limits
elasticity - can return to original resting lenghth
label the diagram with the components of a muscle
how are muscle fibres divided so they can be contracted?
muscle fibres are divided into motor units - one motor neuron linking to many muscle fibres.
when the motor neuron is stimulated, all of the fibres in the moto unit contract
what is a sacromere?
the functional unit with actin and myosin, seperated by Z lines
what is the first step in the sliding fillament theory
The myosin head requires energy (ATP) to activate it so that it can form a cross-bridge with the binding site on the actin
what is the second step in the sliding fillament theory?
The hydroylsis of ATP into ADP and Pi primes the myosin head into the high energy state
what is the third step in the sliding fillament model?
the cross-bridge is formed with mysoins head (thick fillament) attached to actin (thin fillament)
what is the fourth step in the sliding fillament model?
The myosin head pulls the actin filament towards the centre of the sarcomere
how is muscle contraction controlled?
the myosin binding cross-bridge sites are blocked by tropomyosin and troponin. calcium binds to these sites and pulls them away to allow contractions by exposing the sites.
muscle contraction is controled by the movement of cacium in and out of the cell!
how is the quantity of calcium regulated?
calcium is pumped into the cell when it recieves a stimulus from the motor neuron
pumped out of the cell when the stimulus stops
what is the process of cacium release and where is it stored?
signal sent from brain to motor neuron to contract muscle
at the synaptic terminal of the motor neuron, ACh (acetylcholine) is released
signal of ACh continue to t-tubules through sarcroplasmic reticulum
causes calcium to be released –> muscle contractions
how are there different contractions of different muscles? eg the muscles in the eye vs leg
the strenghth of a muscle contraction depends on:
- the number of fibres in a motor unit
- the number of motor units recruited
eyes have very few muscle fibres
legs have many muscle fibres
what happens when there are many action potentials at a high frequency?
the tension increases into a smooth contraction called tetanus
