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College muscle metabolism
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College muscle metabolism block 2.3Physical exercise zorgt niet voor veel gewichtsverlies.
Energy delivery
Als een spier actief is splitst het ATP in ADP, door verlies van fosfor van ATP hierbij komt energie vrij
die nodig is voor spiercontractie.
Uit de macronutriënten die we eten zijn glucose en free fatty acids the main stoffen voor energie.
In rust zijn free fatty acids de voornaamste bron van energie. Dit komt omdat je veel meer vet op
komt slaan dan glucose.Triglycerids are being deposed in adipose tissue: at least 7 kg. 1 kg fat is about
8000 kcal.
A man burns around 2500 kcals a day. So if you want tob urn 1 kg of fat, you shouldnt eat anything for
3 days.
If you want to loose fat you would better reduce the energy intake, instead of exercise.
Glucose can also be stored: it has to be converted to glycogen, and is being stored in muscle and liver.
In the liver you can store and release glucogen.
The muscle can not secret glycogen.
Our body stores only around 800 grams of glycogen energetic content of glucose in our body way
less than fat.
Fat can generate more energy, but it requires oxygen.
As long as the exercise intensity is not too high, you will be able to obtain enough oxygen and burn
fatty acids.
When the exercise intensity increases, the aandeel of carbohydrates usage for energy starts to
increase.
When there is no/not enough oxygen available, you have to rely on anaerobic conditions generating
ATP.
Marathon: most of the run you use free fatty acids. But when you have to sprint for example you start
to use glucose/carbohydrates.
Glucose and fat are the main sources.
Aërobe dissimilation takes place in mitochondria. This is the place where the degradation of fatty
acids takes place: beta oxidation. In the TCA cycle and beta oxidation NADH and FADH2 are being
formed.
The far majority of ATP is being formed in mitochondria.
You get 38 ATP: 2 from glycolyse and 36 from oxidative fosforylation from glucose.
And you get … from fatty acids.
ATP = adenosine tri-fosfaat. It is required for cross-bridge cycling: myosine and actin binding.
The band between 2 fosfate groups is a energy rich bound: so when it is released, the energy can be
used for fueling the processs.
The body will always try to maintain the ATP levels.
ÄTP ADP + Pi + energy
Fosfate creatine??? Makes sure the ADP obtains another Pi again and becomes ATP.
When the levels become too low, you are in danger of death.
There is always water present, so hydrolysis of ATP is always possible: generating energy by releasing
, a phosphate group is always possible.
Sources of ATP
- ATP present instantaneously: always present amount.
- ADP and CrP
- Plasma glucose: glycolysis. You can generate here 4 ATP, but you need an input of 2 ATPs: netto gain
is 2 ATP.
- Muscle and liver glycogen: can be converted to glucose-6-phosphate can go to glycolysis ATP.
Glucose can only leave the liver cell, not the muscle cell. Glucose kinase is present in liver: kan
glucose loslaten en hechten. In levercel is iets vergelijkbaars aanwezig dat glucose alleen kan binden,
waardoor het gevangen zit in de cel.
- Triglycerids in adipocytes.
- Lactate: is een bijproduct van anaërobe glycolyse. Kan ook weer terug worden omgezet in glucose in
de lever. Het is daarnaast een belangrijke stof omdat het ervoor zorgt dat je anaëroob kunt blijven
verbranden.
- Carbon backbone of amino acids. Amino acid can serve to generate glucose: gluconeogenese.
ATP-production from oxidative fosforylation in mitochondria (aerobic)
Rode bloedcellen hebben geen mitochondrion kunnen geen vetten gebruiken, dus gebruiken
glucose.
Cel zie plaatje: de vetdruppeltjes liggen direct naast de mitochondria: zo kunnen ze triglyceriden
afgeven, en kan er ATP gevormd worden in de mitochondria spiercontractie.
Volgende plaatje: spier van een getrainde atleet. Hierbij zijn er zeel veel mitochondria en zeer veel
vetdruppeltjes te zien. Dit kan een effect zijn van exercise training. Als je stopt met trainen verlies je
het weer. Ook worden sommige mensen geboren met veel mitochondria (erfelijk).
Ook zijn er 2 grote rondjes met grijze inhoud te zien: dit is een capillair (erythrocyt in capillair) kan
zorgen voor O2 overdracht naar mitochondrium.
ATP production from glycolysis (anaëroob)
De grijze stipjes die te zien zijn zijn glycolyse droplets?
ATP production from oxidative fosforylatie in mitochondria: aëroob.
De elektronen transport keten transporteert elektronen.
There are 4 or 5 complexes dependend on how you count.
NADH+ donates 1 H+ and one elektron to complex 1. When you start pumping protons across the
membrane, you star to generate a proton gradate. De H+ zitten in het inner mitochondrial
membrane.
There are being transported protons from complex to complex. In this way you generate a proton
gradate. There is a elecrtric charge, and this can be used by ATP synthase, to generate ATP from
ADP+Pi.
If you have ATP and you split in to ADP+Pi, energy is being released. So if you want to form ATP, you
need energy. This amount of energy is formed by pumping the H+ back.
Complex 4 = cytochrome C oxidase: this one requires oxygen. Oxygen uptake takes place in
cytochrome C oxidase.
Elektron transport chain in mitochondrial cristae: this is the inner mitochondrial membrane.
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