Osmolarity detecting cells located in nuclei of the become stimulated by an increasing blood solute concentration.

Osmolarity detecting cells are located in the nuclei of Hypothalamus.

Explanation:

Osmolarity is use to determined how much of osmoles of solute per liter concentration. I.e how concentrated the solute is, it is usually expressed as Osm/L. Osmolarity is detected by specialized osmolarity detecting cells called ooreceptors located in the nuclei of hypothalamus and this are stimulated by increasing blood solute concentration.

it provides an alternative energy pathway for the reaction to proceed.

a catalyst is a substance that speeds up the rate of a chemical reaction but is not consumed during the course of the reaction.

catalysts increase the rate of reaction without being used up. they do this by lowering the activation energy needed. with a catalyst, more collisions result in a reaction, so the rate of reaction increases. different reactions need different catalysts.

a catalyst works by providing an alternative reaction pathway to the reaction product. the rate of the reaction is increased as this alternative route has a lower activation energy than the reaction route not mediated by the catalyst.