Just out of interest.... Watch

nikk
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When cardiac muscle is starved of oxygen, it obviously very rapidly develops permanent damage or even dies.

I was just wondering if anyone knew exactly what damage occurs in the absence of oxygen that causes this? I would assume it would perhaps be due to loss of a H+ gradient across the inner mitochondrial membrane or something like that?

I don't particularly need to know this but thought it was quite interesting.
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Revenged
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(Original post by nikk)
When cardiac muscle is starved of oxygen, it obviously very rapidly develops permanent damage or even dies.

I was just wondering if anyone knew exactly what damage occurs in the absence of oxygen that causes this? I would assume it would perhaps be due to loss of a H+ gradient across the inner mitochondrial membrane or something like that?

I don't particularly need to know this but thought it was quite interesting.
All I know is that cell death and shrinking of cell size due to lack of oxygen is called atrophy
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shinyhappy
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Damange from lactic acid as it switches to anaerobic respiration?
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nikk
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(Original post by shinyhappy)
Damange from lactic acid as it switches to anaerobic respiration?
Highly unlikely I would imagine...in the absence of oxygen, the cardiac tissue would be dead well before lactic acid had time to build up. I think the heart goes into fibrilation even if deprived of oxygen for 1 or 2 seconds.

I reckon it is something to do with the mitochondria loosing their H+ gradient. I know that mitochondria can induce apoptosis when significant numbers of them become damaged, so perhaps something like that happens.

Where are those cardiac surgeons when you need them eh? :p:
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Revenged
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(Original post by nikk)
Highly unlikely I would imagine...in the absence of oxygen, the cardiac tissue would be dead well before lactic acid had time to build up. I think the heart goes into fibrilation even if deprived of oxygen for 1 or 2 seconds.

I reckon it is something to do with the mitochondria loosing their H+ gradient. I know that mitochondria can induce apoptosis when significant numbers of them become damaged, so perhaps something like that happens.

Where are those cardiac surgeons when you need them eh? :p:
Ok, i see what you are on about...

You need oxygen as the last electron receptor in the electron transport chain.

If you have insufficient oxygen, then you are limiting the rate of oxidative phosphorylation...

this would mean that less NADH and FADH2 would be oxidised, less electrons be transferred down the cytochromes, this would cause less H+ to be pumped into the mitochondrial space and thus you lose the H+ gradient in the mitochondria (if this lack of oxygen was great enough)...

loss of the mitochondrial H+ gradient would prevent the formation of ATP from ADP into the stalked paricles...
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Comp_Genius
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I think the lack of oxygen results in lack of energy production, thereby stopping the sodium-potassium pump, Na+ accumulates, myocytes draw in water and lyse, necrosis results.
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nikk
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Thanks guys!

Revenged: I understood that much, but was more wondering what the final 'killer punch' (lol) was to the cells....which Darkenergy has just said I know any tissue couldn't last that long without oxygen, but wanted to know specifically what it was that caused the damage you see in heart attack patients.
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Comp_Genius
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oh and K+ accumulation in the ECF causes fibrillation, and thence, death.
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Tom H
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Well one definition of death is reaching equilibrium. With no energy source (or an insufficient energy source) to maintain gradients death ensues.
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idiopathic
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(Original post by nikk)
Highly unlikely I would imagine...in the absence of oxygen, the cardiac tissue would be dead well before lactic acid had time to build up. I think the heart goes into fibrilation even if deprived of oxygen for 1 or 2 seconds.

I reckon it is something to do with the mitochondria loosing their H+ gradient. I know that mitochondria can induce apoptosis when significant numbers of them become damaged, so perhaps something like that happens.

Where are those cardiac surgeons when you need them eh? :p:
Intracellular acidosis does occur from ischaemia, and the H+ are actually a negative inotropic factor which reduces the contractility further!
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Comp_Genius
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(Original post by Tom H)
Well one definition of death is reaching equilibrium. With no energy source (or an insufficient energy source) to maintain gradients death ensues.
Increase in entropy, huh?:rolleyes:
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