muscles Flashcards
outline the structure and features of myosin
fiborous protein
forms thick filaments
has heads
heads lie in bundles at each end
outline the structure and features of actin
globular protein
thin filaments
2 actin chains twist around each other
tropmyosin lines inbetween the actin chains
troponin globular protien binds regularlary to the actin chains
outline fast twitch fibres
contract faster
more powerful
work for shrort periods
intense
outline the adaptations of fast twitch fibres
thicker myosin
more glycogen
more anaerobic enzymes
more phosphocreatin which converts ADP to ATP in anaerobic conditions
outline slow twitch fibres
contract slower
less powerul
work for longer periods
endurance
what are the adaptations of slow twitch fibres for aerobic respiration
more myoglobin
greater blood supply
more mitochondria
what happens to muscles when they are relaxed
Actin has myosin binding sites
when relaxed these sites are blocked by tropomyosin
what are the similarties between neuromuscular junctions and cholingeric synapses
neurotransmitters that are transported by diffusion
use of enzymes to break down neurotransmitter
use of a sodium potassium pump to repolarise the axon
have receptors on binding with neurotransmitter cause sodium ion influx
what are the three types of muscle
cardiac muscle
skeletal muscle
smooth muscle
what is cardiac muscle
muscle that contracts without conscious control
only found in the heart
what is skeletal muscle
muscle that you use to move
what is smooth muscle
muscle that contracts without conscious control found in walls of internal organs
what are antagonistic pairs
muscles that work together to move a bone
contracting muscle agonist
relaxing muscle antagonist
what do myosin filaments have on them
hinged globular heads
each head has binding site for actin and binding site for ATP
what do actin filaments have on them
binding sites of myosin heads
tropomyosin found between actin filaments
outline the arrival of an action potential in muscle contraction
action potential depolarises sarcloemma
slowing down T-tubulus casuing release of Ca2+ ions
into sarcosplam
Ca2+ ions bind to tropomyosin causing it to change shape
This pulls tropomyosin out of binding site on acting filament allowing myosin head to bind to exposed binding site
actin-myosin cross bridge forms
out line the movement of the actin filament in muscle contraction
Ca 2+ ions actiavate ATPase which hydrolyses ATP
to release energy needed for muscle contraction
energy released from ATP causes mysoing head to bend pulling actin filament along
outline the breaking of the cross-bridge
another ATP molecule provides energy to break cross bridge
mysoin head detaches from actin filament after it’s moved and reattaches to a new binding site further along actin filament.
new cross bridge forms and cycle is repeated
outline the process of muscle relaxtion
nervous stimulation stops
Ca2+ ions reabsorbed into sarcoplasmoc reticulum by A/T
tropomyosin moves back
myofibrils relax
what is ATP needed for in muscles
movement of myosin head back to the normal
reabsoprtion of Ca2+ into the sarcoplasmic reticulum
what do muscles store to help produce ATP
phosphocreatine
it converts ADP to ATP
what is the reaction of phosphocreatine and ADP
ADP + phosphocreatine – ATP + creatine
where is excess phosphocreatine broken down
it is broken down in the kidneys
what are the four pieces of evidence for the sliding filament theory
A band stays the same
I band becomes narrower
Z lines move closer together
H band narrows
what is the evidence for the I band becoming narrower
the actin moves
what is the evidence for the Z lines moving closer together
The whole sarcomere shortens
what is the evidence for the H band narrowing
Actin slides over mysoin
what is the evidence for the A band staying the same
Myosin filaments do not shorten
