Question

A male eats a full bag of salty potato chips. What effect does this have on urine concentration and volume? Explain the mechanisms involved.

Answer 1

I've got a meeting coming up at noon but I'll be back afterwards - in the mean time look up ADH and aldosterone. Reduction of aldosterone might be responsible for the effects.

Answer 2

I think the blood volume will increase with the salt in the crisps. This will increase the firing of the stretch receptors in the atria of the heart (these are the pressure sensors for the atria). Less aldosterone will be produced as a result and so less salt will be reabsorbed at the kidney. The urine will be more salty and hence the volume will be greater.
There will probably be less ADH (unless the man is dehydrated) because the blood volume is less and so less water reabsorption at the kidney, thus getting rid of the salt in a bit more urine than normal.

Answer 3

Wouldn't the blood osmotic potential increase due to high concentration of salt in the blood? And thus urine produced will be less?
This is all so confusing. >_<
Plus, there is one more question.
If a person loses alot of blood in an accident, what effect will this have on ultrafiltration in the kidneys?

Answer 4

The vital concept here is homeostasis: the body responds to changes to maintain the internal environment. My idea was that the salt in the crisps will be got rid of by alterations in the amount and osmolality of the urine. Then things go back to normal.

As for the other question, low blood volume would stimulate aldosterone so more sodium (salt if you like) will be reabsorbed by the kidney. The dehydration caused by the blood loss would increase ADH (antidiuretic hormone). This means that more water is reabsorbed at the kidney and the amount of urine is less. This would help maintain the blood volume and hence pressure.

PS Anti diuretic hormone is well named - a diuresis is a large amount of watery urine and the hormone stops this happening when water is needed ie in cases of dehyration.

Answer 5

Ok, I understand that. But I read this on one website;
www.online-vitamins-guide.com/nutrition-articles/osmoregulation.htm

In some cases, both volume and osmolality are altered and both pathways are activated. For example, if a person with normal renal function eats salted potato chips and peanuts without drinking any water, the excess Na + will increase the plasma osmolality, leading to osmotic water movement out of the cells and increased extracellular volume. The rise in osmolality will stimulate both ADH release and thirst (the main reason why many restaurants and bars supply free salted foods), whereas the hypervolaemia will enhance the secretion of ANP and suppress that of aldosterone. The net effect is increased excretion of Na + without water.