The osmotic pressure of the plasma affects the mechanics of the circulation in several ways. An alteration of the osmotic pressure difference across the membrane of a blood cell causes a shift of water and a change of cell volume. The changes in shape and flexibility affect the mechanical properties of whole blood.
Weekly. Potatoes need one solid watering every week. Accounting for naturally occurring moisture is an important when judging how often to water. A light shower doesn't penetrate deeply enough into the soil, so you should still proceed with your weekly watering after receiving one.
It sounds like your plants succumbed to the heat. Potatoes are extremely sensitive to high temperature and dry soil, among other things. One source estimated that one potato plant's total water consumption in a season is about 26 inches (over several months) for plants in the ground. was brought up to plant potatoes (New England) on or before St. Patrick's Day regardless of weather/frost-it worked there and has worked well for 30 yrs. in the Willamette Valley (Oregon-USA) harvest 1st crop early June, 2nd crop in late summer.