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Biological Miracle – Wood Frog

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503 points thunderbong | 2 comments | 15 Nov 24 18:16 UTC | HN request time: 0.528s | source
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abound ◴[16 Nov 24 04:12 UTC] No.42154107[source]▶
> Nobody yet understands what starts the wood frog’s heart after being frozen and inert for the entire northern winter.

To me, that's the most fascinating part of the (already quite fascinating) story. Frog is frozen solid, there is no (to our knowledge) heartbeat or brain activity. It thaws and something happens that gets it going again.

I have trouble imagining what that mechanism could even look like. Tiny portion of brain responsible for keeping track of frozen-ness? Some chemical signaling from within the body cavity?

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telgareith ◴[16 Nov 24 04:28 UTC] No.42154234[source]▶
my poor knowledge of biology says it's a deeply unsatisfying "heart beats when enough of the body has thawed for it to beat."

If the heart depends on the brain at all in frogs.

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nine_k ◴[16 Nov 24 05:02 UTC] No.42154434[source]▶
It doesn't, even in humans. There is an independent circuit of special muscle cells right on it that keeps it beating.

So starting and stopping the heart in a controlled manner is pretty interesting, because it has to be well-timed, and there are few obvious and reliable inputs to control it, especially when thawing.

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1. telgareith ◴[16 Nov 24 15:56 UTC] No.42156999[source]▶
"Even in humans"- thats a pretty steep assumption.

I am fully aware that if the human heart is severed from the brainstem it will develop A rhythm.

But what about other mammals? Dunno. Not going to assume.

Theres also the tidbit that frogs are not mammals.

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2. nine_k ◴[16 Nov 24 19:05 UTC] No.42158411[source]▶
The point is that whatever control a frog heart may have, it's not cerebral. It must be a very low-level circuit, which can be modulated from outside, but which remains autonomous.