The dilution of infant formula with water can cause water intoxication in infancy. Some parents cannot afford formula and will give their babies water to drink. They baby feels satisfied after the drinking of the water and that makes the mother or caregivers think that water is enough for the hungry infant. Formulas are often diluted with water, this can also cause Kwashiorkor due to a protein deficiency. The child seems well fed because of the child's distended abdomen.
I was working as a professional nurse for many years and saw the consequences of diluted formulas or even 'mealie pap' given in a very diluted form to hungry infants.
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A thirsty person usually has a dry mouth, which is a consequence of the loss of extracellular water and resulting decreased flow of saliva.
Thirst is the primary regulator of water intake. "The intense feeling of thirst derives from the osmotic pressure of extracellular fluids and a thirst center in the hypothalamus of the brain. The thirst mechanism is normally triggered whenever the total body water is decreased by as little as 1%." Ricki Lewis
If a person drinks too much water, the plasma becomes less concentrated and the osmoreceptors swell as they receive extra water by osmosis.
Nerve impulses that inhibit the thirst mechanisms are triggered when the stomach wall is distended after the drinking of water, drinking water stops long before the swallowed water is absorbed. This inhibition stops the person from drinking more than is required to replace the quantity lost, avoiding development of an imbalance of the opposite type.
Sources:https://en.wikipedia.org/wiki/Kwashiorkor#/
https://sciencing.com/happens-cells-dehydrated-23904.html
@frieda