muscles Flashcards
(36 cards)
what is the biggest component of muscle
- water (70-78% of muscle)
- protein (15-22)
- lipid (1-13)
- carbohydrate (glycogen) (2)
myofibre structure
- rod like
- sarcoplasmic reticulum around them -> calcium
- transverse-tubules
- mitochondria around -> ATP
- z discs -> ccontracting unit between 2 (M line) -> striated
what happens if ATP runs out during muscle cycle?
- can’t let go
- rigormortis -> myosin hooked up to actin indefinitely
- before this happens after death, all ATP therefore glycogen and oxygen
- build up of lactic acid from anaerobic ATP forming decreases pH -> means that enzymes go slower, less ATP formed over time = more rigormortis occurring
what makes up sarcomere
- two z discs and m discc -> z has actin, m has myosin
if meat had shorter sarcomeres, would meat be tougher or more tender?
more tough (bound together closely)
what is the perimysium
- layer of connective tissue in muscle
simple steps of muscle contraction:
- nerve impulse to muscles fibre via perimysium and t tubule
- depolarisation of he sarcoplasmic reticulum causes Ca2+ release
- Ca2+ initiates contraction cycle
what are the layers of connective tissues in muscle
- edomysium -> cover muscle fibres (single cells covered)
- perimysium -> cover muscle bundles
- epimysium -> cover muscles
how is elastin different to collagen
- less of it in connective
- doesn’t break down when heated
- makes meat tougher
what are collagen crosslinks
- chemical bonds linking collagen fibres
- give tensile strength to connective tissue
- increases with age
- meat tougher
would a fast twitch muscle need more TCA or more glycolysis?
- glycolysis because it can be sped up much more to make ATP -> anaerobic = less oxygen needed
where is oxygen stored in muscles
myoglobin -> red
what does a more white muscles tell you?
- most likely a fast twitch muscle
- needs less oxygen for ATP because its using less TCA cycle and more glycolysis for faster ATP
- glycolysis is anaerobic therefore needs less O2
- therefore muscle stores less oxygen in myoglobin = less red
what is the eye round muscle
- really elastic
- bad quality meat
- white -> fast twitch
why are long distance runners better at metabolising fats
- increased mitochondria in muscles
- increased expression of enzymes in lipolysis and transport -> increased hormone sensitive lipase
- mitochondria has upregulated beta oxidation and more TCA cycle
- more slow twitch isoform of myosin head
what are the 3 types of muscle fibres?
Type I - slow twitch and aerobic (TCA), high in myoglobin and mito, fatigure resistant - oxidative -> rely on fat metabolism (very efficient process) so less glycolysis
Type IIA - fast twitch, aerobic, high in myoglobin and mito (TCA) -> oxidative
Type IIB - fast twitch, anaerobic, low myoglobin and mito, easily fatigued - white muscle -> produce more lactic acid
what enzymes will signal anaerobic muscles
- ## PFK, F1,6bP, LDH (makes lactic acid)
what enzymes/proteins will signal aerobic muscles
- citrate synthase, ICDH, myoglobin
what glycogen enzymes are high/low in each muscle fibre type
I -> low hexokinase, low glycogen synthase, high glycogen phosphorylase
IIA -> low hexokinase, medium glkycogen synthase, high glycogen phosphorylase
IIB -> very low hexokinase, low synthase and very high phosphorylase (lots of glycolysis)
where are the biggest differences in muscle colour
- between muscles within someones body -> have different functions
why does muscle lose fast twitch fibres over time?
- shift away from glycolytic towards slow oxidative
- because slow oxidative are more metabolically efficient (glycolysis is not, but is fast)
- get redder over time
if you select for msucling
- get whiter, less myoglobin = less iron
what would happen to muscle if we selected animals for rapid growth
- less iron
- whiter
how do muscles metabolism post death
- glycolysis -> anaerobic
- creatine phosphate
