Muscle Contraction Flashcards
ATP’s role
attachment between myosin and actin
power stroke/movement of head
detachment of head
myosin head moving back to original position
role of calcium ions and ATP
Ca2+ from sarcomere diffuses to myofibrol
causes movement of tropomyosin
exposed binding sites on actin
myosin head attaches - hydrolysis of ATP = bends
pulls over actin molecules
attachment of new ATP to myosin head
head detaches
ATP is a suitable energy source
readily available
doesn’t leave cells
small amounts lost as heat
rapidly resynthesised
ATPase in muscle fibres
hydrolysis of ATP
muscles contractions require ATP
since ATP used by myosin
ATP in muscle fibres Fast v Slow
Fast - atp hydrolysed
Slow - atp synthesised
light microscope vs electron microscope
light required to see colour - cannot with electrons
if myosin molecules can’t bind
- no formation of thick filament
- myosin needs to joined to pull actin
- actin can’t be moved towards each other
high number of mitochondria
high percentage of slow muscle fibres
slow muscle fibres use aerobic respiration which occurs in mitochondria
training specific muscles
increases DIAMETER of muscle fibres
due to training
so a higher percentage of specific slow/fast fibres
conclusions about muscles
previous muscles
age sex or diet
role of phosphocreatine
provides phosphate to make ATP
ADP + PC ATP + C
variation
Genetic differences Level of fitness Sex Ethnicity Metabolic rate Number of fast / slow muscle fibres
time for PC to be resynthesises increases as age increases
fast fibres used for rapid + strong contractions
PC used rapidly during contraction to make ATP
older = slow metabolic rate/ATP production/respiration
ATP used to reform phosphocreatine
contraction length
I band + H zone = shortens
A band = stays the same
