Why there is urine-formation in our body more in winter than in summer?
SATNAM SINGH SIDHU
Water is an essential element of our metabolism. This is useful in maintaining the fluidity of blood, flow of nutrients through out the body, transport of important chemicals such as hormones, enzymes and also for removal of wastes from the body. Excess water containing wastes is lost from the body in the form of urine, sweat, feces and direct loss (under very hot and dry conditions). Maximum amount of excess water is lost through urination.
During summer when the surrounding temperature is high, we lose water in the form of sweat, direct evaporation considerably. Hence kidneys retain water for maintaining fluidity of the blood and less urine is formed.
But during winter, the surrounding temperature will be very low. There will not be any sweating, no evaporation losses. Moreover to keep the body temperature constant, the blood capillaries in the skin get constricted and the blood pressure is increased. The result is that our body gets warmed up. In order to maintain the blood pressure normal, the excess water along with the wastes is excreted mostly in the form of urine. This is the reason for more urine out put and frequent urination under very cool conditions and in winter.
The adreno-cortico steroidal hormones play an important role in this regard by sending signals to kidneys. Kidneys can sense and decide the necessity for water intake by creating the thirst feeling. Kidneys maintain the balance of water content in body for the smooth conduction of various metabolic activities that take place in our body.
Normal urine is either colourless or pale yellow coloured containing uric acid, water, casts, salts and other unwanted materials causing no discomfort while urinating. A severely dehydrated person may not pass urine at all!! The colour of the urine is a warning sign in many diseases!
Dr. T. BHAVANI, Bangalore