Thermogenesis without shivering

[Nomegusta]

Or the thermogenesis in brown adipose tissue. Can someone explain me the core of it and how is it connected with respiratory chain and ATP synthesis. Thank you!

[BabcockHall]

Do you have any thoughts on how it might happen? Do you know how ATP is mainly synthesized in mitochondria? Maybe one place to start would be what causes the brown color.

[Nomegusta]

Do you have any thoughts on how it might happen? Do you know how ATP is mainly synthesized in mitochondria? Maybe one place to start would be what causes the brown color.

 

Well what i know is that :

 

- the respiratory chain is composed of protein complexes in inner membrane of mytochondria. One purpose is that- because in the process of oxydating coenzyme and reducing oxygen the large amount of energy is relased so the process is divided into protein complexes and the energy is relased in portions. By this being done , the large amount of H is pumped from matrix into the perimembrane space and thus the gradient of protons is created which is then used by the ATP synthase to form ATP.

 

-also the mitochondria in the brown adipose tissue has many modified mitochondria. They have many big rounded mitochondria with many crystae. And they also have UCP (uncoupling protein) .

 

And there is where my knowledge stops ... So is it the energy that is "unspent" in ATP synthase or oxydation of coenzymes used by UCP or what? I just need a few coordynates.

 

P.S. and for the brown color i assume is the large amount od mytochondria and i am sorry for misspelled words

[BabcockHall]

The favorable movement of electrons from NADH to oxygen is coupled to the unfavorable translocation of protons across the mitochondrial membrane. The return of these protons through ATP synthase is coupled to the synthesis of ATP. Some substances, such as dinitrophenol, are poisonous because they act as uncouplers. Do you happen to know how they work? Thermogenin works in a similar manner, although one might argue that it is not an identical manner. The cytochrome proteins of the mitochondria are partially responsible for the brown color.

[Xalatan]

I also think thermogenin may be the answer here. When the proton channel is physiologically uncoupled from atp synthase heat may be generated by the ETC. Also since aerobic glycolysis and cell respiration are catabolic in nature some heat may be given off by these chemical reactions.

Shivering on the other hand is an autonomic neural reflex that loops the hypothalamus and spinal cord. This is different to the metabolic heat production from glucose use.

[CharonY]

The answer is skirting around the mechanism but is not quite complete. Obviously just dissipating the proton gradient in itself does not generate more heat, as long as there is not difference in the chain itself. The reason being that the ETC is physiologically uncoupled from the ATP synthesis step to begin with.

The key is that the cells enters a futile cycle and the consequences it brings (i.e. think in terms of stochiometric coupling of mitochondrial energy metabolism, if that helps).

Edited March 7, 2016 by CharonY