A check valve, clack valve, non-return valve or one-way valve is a valve that normally allows fluid (liquid or gas) to flow through it in only one direction. Check valves are two-port valves, meaning they have two openings in the body, one for fluid to enter and the other for fluid to leave.
Some causes of cold intolerance are: 1  Anemia. 2  Anorexia nervosa. 3  Blood vessel problems, such as Raynaud phenomenon.  Chronic severe 1  illness. General poor health.  Underactive thyroid 1  (hypothyroidism) Problem with the hypothalamus (a part of the brain that controls many body functions, including body temperature)
Only a doctor can diagnose the cause of your hot and cold symptoms, but these flashes are very often caused by anxiety. If you haven't yet, click here to take my free anxiety test and learn more about anxiety and hot flashes. The Hot And Cold Experience. These Flashes are really just changes to your body temperature. During periods of intense anxiety, your body temperature heats up due to vasoconstriction, which is when your blood vessels tense up as they deliver more blood to the areas involved in fight and flight.