Betsy_Lou
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Hi!

Is negative feedback a process by which:

i) a factor of the internal environment is corrected (e.g blood glucose)
ii) a response is corrected (e.g insulin)
ii) both

Please expand on what negative feedback is if possible (a comprehensive definition would be much appreciated).
Thanks for any help, I’m really struggling with feedback mechanisms.
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999tigger
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(Original post by Betsy_2018)
Hi!

Is negative feedback a process by which:

i) a factor of the internal environment is corrected (e.g blood glucose)
ii) a response is corrected (e.g insulin)
ii) both

Please expand on what negative feedback is if possible (a comprehensive definition would be much appreciated).
Thanks for any help, I’m really struggling with feedback mechanisms.
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Ell1e10
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It’s quite hard to explain but I can show you an example. So basically you have probably heard of Adrenalin and thyroxine. Adrenalin does not have a negative feedback mechanism because you only need the hormone in scary situations so it not does need to be regulated. Whereas, thyroxine is a negative feedback because your body needs to keep constant all the time so when the thyroxine is low it needs to be increased and when it’s high it needs to be decreased, it never is just right. I don’t know if that’s helpful but yeah.
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Betsy_Lou
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(Original post by Ell1e10)
It’s quite hard to explain but I can show you an example. So basically you have probably heard of Adrenalin and thyroxine. Adrenalin does not have a negative feedback mechanism because you only need the hormone in scary situations so it not does need to be regulated. Whereas, thyroxine is a negative feedback because your body needs to keep constant all the time so when the thyroxine is low it needs to be increased and when it’s high it needs to be decreased, it never is just right. I don’t know if that’s helpful but yeah.
Thank you very much!
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Ell1e10
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(Original post by Betsy_2018)
Thank you very much!
No worries! Hope I helped a bit
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macpatgh-Sheldon
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I haven't looked at video above, but OP might be an A level student [likely].

Let me walk you through it (without holding your hand - guys double my size scream when I handshake them!!

The best way to understand the concept is via examples. In the human body various substances/parameters need to be kept constant in order to allow proper biochemical/physiological processes to occur. You have come across homeostasis, yeah?

Ok let us take our first example - heard of thyroxine? ("Does he think I am stupid?" she recoils in disgust! - don't worry, not trying to insult you! - just that it is best to start from basics and work up - also, I do not know your level.

T4 (thyroxine) is an iodine-containing hormone (T4 cos it contains 4 atoms of iodine in a molecule [for A* thri-iodothyronine [T3] contains 3 atoms od iodine]) produced by the thyroid gland [a butterfly-shaped gland in your neck. T4 levels need to be constant in the blood, so there is a hormone produced by the pituitary gland in the brain [near the optic chiasma [where the two optic nerves cross to then emanate as optic tracts going towards back of brain where you see - it's not only teachers who have eyes on the back of the head - everyone does!! - Greek letter chi is an English "x" - that is the shape of this part - like a cross]] called TSH (thyroid stimulating hormone), which stimulates the release of T4 from the pituitary.

If the thyroxine levels in the blood are high, THIS TENDS TO REDUCE THE SECRETION of TSH from the pituitary = NEGATIVE FEEDBACK, because obviously you do not want to increase already high T4 levels [by TSH stimulating the thyroid] - yeah - still with me? [if you are lagging behind, put your gear up by one or two on your bike (gear adjustment lever on right handlebar end OR get your mum to cook some hot curry for lunch!! ] We medics sometimes measure TSH levels in the blood as an indirect way of checking if the thyroid is under- or over-active - still happy or are you reaching for the box of tissues?

Ok if you are still awake (you should be,cos I have not been singing, have I? ), let us take 2nd example.

Prolactin [Greek lacto= milk as in lactose = milk sugar] is a hormone that stimulates a woman's breasts to secrete milk to feed a young baby. The pituitary [once again cos this gland controls most other glands in the body] secretes a "hormone" called PIF (prolactin inhibiting factor). When breast milk levels are sufficient, the secretion of PIF decreases [and vice versa]. The first scenario [when PIF drops] is NEGATIVE FEEDBACK, so the lactating mother does not need to wear 5 bras (!!). Ok it would be useful if she had triplets!

Is everything clearer now? Sorry the jokes were meant to stop you from drifting away and starting to text your friends at the same time (as they say, girls can multitask haha).

M
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Betsy_Lou
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(Original post by macpatelgh)
I haven't looked at video above, but OP might be an A level student [likely].

Let me walk you through it (without holding your hand - guys double my size scream when I handshake them!!

The best way to understand the concept is via examples. In the human body various substances/parameters need to be kept constant in order to allow proper biochemical/physiological processes to occur. You have come across homeostasis, yeah?

Ok let us take our first example - heard of thyroxine? ("Does he think I am stupid?" she recoils in disgust! - don't worry, not trying to insult you! - just that it is best to start from basics and work up - also, I do not know your level.

T4 (thyroxine) is an iodine-containing hormone (T4 cos it contains 4 atoms of iodine in a molecule [for A* thri-iodothyronine [T3] contains 3 atoms od iodine]) produced by the thyroid gland [a butterfly-shaped gland in your neck. T4 levels need to be constant in the blood, so there is a hormone produced by the pituitary gland in the brain [near the optic chiasma [where the two optic nerves cross to then emanate as optic tracts going towards back of brain where you see - it's not only teachers who have eyes on the back of the head - everyone does!! - Greek letter chi is an English "x" - that is the shape of this part - like a cross]] called TSH (thyroid stimulating hormone), which stimulates the release of T4 from the pituitary.

If the thyroxine levels in the blood are high, THIS TENDS TO REDUCE THE SECRETION of TSH from the pituitary = NEGATIVE FEEDBACK, because obviously you do not want to increase already high T4 levels [by TSH stimulating the thyroid] - yeah - still with me? [if you are lagging behind, put your gear up by one or two on your bike (gear adjustment lever on right handlebar end OR get your mum to cook some hot curry for lunch!! ] We medics sometimes measure TSH levels in the blood as an indirect way of checking if the thyroid is under- or over-active - still happy or are you reaching for the box of tissues?

Ok if you are still awake (you should be,cos I have not been singing, have I? ), let us take 2nd example.

Prolactin [Greek lacto= milk as in lactose = milk sugar] is a hormone that stimulates a woman's breasts to secrete milk to feed a young baby. The pituitary [once again cos this gland controls most other glands in the body] secretes a "hormone" called PIF (prolactin inhibiting factor). When breast milk levels are sufficient, the secretion of PIF decreases [and vice versa]. The first scenario [when PIF drops] is NEGATIVE FEEDBACK, so the lactating mother does not need to wear 5 bras (!!). Ok it would be useful if she had triplets!

Is everything clearer now? Sorry the jokes were meant to stop you from drifting away and starting to text your friends at the same time (as they say, girls can multitask haha).

M
Haha thank you so much! That was an enjoyable and helpful read!
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macpatgh-Sheldon
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(Original post by Betsy_2018)
Haha thank you so much! That was an enjoyable and helpful read!
"T4 levels need to be constant in the blood, so there is a hormone produced by the pituitary gland in the brain [near the optic chiasma [where the two optic nerves cross to then emanate as optic tracts going towards back of brain where you see - it's not only teachers who have eyes on the back of the head - everyone does!! - Greek letter chi is an English "x" - that is the shape of this part - like a cross]] called TSH (thyroid stimulating hormone), which stimulates the release of T4 from the pituitary."

CORRECTION: the last word in the above paragraph (taken from my answer) should read "thyroid" (of course, the hormone secreted by the pituitary is TSH NOT T4). Apologies for any confusion - just noticed my error!

M
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