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34 Cards in this Set
- Front
- Back
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what does muscle contraction cause?
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ATP consumption, fuels need to be oxidised at a faster rate
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what do contractile filaments do?
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provide driving force and shorten when muscle cells contract
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in muscle cells, what do mitochondria provide?
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energy
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what does sarcoplasmic reticulum contain?
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calcium ions
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what happens to the calcium ions in sarcoplasmic reticulum when a nerve impulse arrives?
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they flood out to bathe contractile filaments as the trigger for contractile filaments to slid across each other
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at rest, what does the muscle have to invest a lot of energy in?
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pumping calcium ions into the sarcoplasmic reticulum and keeping the concentration of calcium ions around contractile filaments very low. so muscle cells use a lot of energy, even at rest
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what is muscle type 1?
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red, slow.
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what are the defining features of type 1 muscle?
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contracts relatively slowly, many mitochondria, good blood supply
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what is muscle type 2b?
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white, fast
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what are the defining features of type 2b muscle?
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contracts relavtively rapidly,
few mitochondria, poor blood supply, packed with contractile filaments |
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what is another name for 'red' muscle?
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slow twitch
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what is another name for 'white' muscle?
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fast twitch
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are type 1 and type 2b the only type of muscle in our bodies?
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no, there are muscles in between. we don't really have any muscles that are exclusively type 1 or type 2b, they tend to be varying mixtures of these types.
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which muscle type would you use when doing low intesity, endurance exercise?
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type 1 red/slow twitch
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which muscle type would you use for sprinting/weightlifting?
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type 2b, white fast twitch
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what does muscle contraction use?
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ATP
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what stimulates muscle contraction?
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rise in cytosolic calcium released from sarcoplasmic reticulum on arrival of a nerve impulse
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in muscle contraction, what is ATP demand met by?
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oxidative phosphorylation (using proton gradient to make ATP) - all the energy comes from the mitochondria (except in some very strenuous, short term exercise)
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what provies the NADH into the electron pathway?
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the krebs cycle
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is the rate the krebs cycle works at increased or decreased during exercise?
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increased
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what are some other names for the krebs cycle?
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TCA cycle, citric acid cycle
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how do you increase the rate of the krebs cycle?
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increase the substrate coming into it (Acetyl-CoA) which comes from fatty acid oxidation and/or glucose oxidation
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what is the overall strategy of the krebs cycle?
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-completely oxidise the 2 carbons in acetate to CO2 and produce lots of H- (major strategy)
-produce lots of NADH, FADH2 and even an ATP -acetates that come into cycle are carried on a carrier molecule (oxaloacetate) therefore second half of cycle is about regenrating oxaloacetate as a carrier |
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what is meant by the contractile filaments 'sliding over' each other?
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the muscle is contracting
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what carries the acetate groups through the krebs cycle?
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oxaloacetate
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what is the reaction from isocitrate to alpha-ketoglutarate?
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oxidative decarboxylation
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what is the reaction from alpha-ketoglutarate to succinyl-CoA?
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oxidative decarboxylation
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what is the reaction from succinyl-CoA to succinate?
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substrate level phosphorylation -succinyl CoA is a high energy molecule which can be used to drive the formed of a tri-phosphate (GTP is produced from GDP and Pi) so ATP(GTP) isn't being made by ATP synathase
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how does oxaloacetate carry acetyl?
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has delta + on middle carbonyl group makes it vulnerable to attack from acetate
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how is substrate level phosphorylation different to oxidative phosphorylation?
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substrate level phosphorylation is making GTP(ATP) directly from a high-energy substrate, whereas oxidative phosphorylation is taking Hs from a substrate then putting them through electron transport chain and F0F1ATPase to create ATP.
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how many carbons go into and come out of the krebs cycle?
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2 go in (acetate) 2 come out as CO2 (1C from acetyl CoA, 1C from oxaloacetate)
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how many ATPs are produced during the krebs cycle?
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~10
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what are rate limiting steps?
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irreversible reactions that tend to be slow due to saturation of enzymes ([S]>>Km, working at Vmax) so changing [S] doesn't alter rate only way to change rate is to change internal properties
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redfern station analogy of enzyme saturation: what are the ways to change intrinsic properties of the 'enzyme'?
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-make more gates open
-make and destroy gates according to need -make ticket reading and gate opening happen faster |
