Interesting Features

Human Physiology

Lesson 23 : Urinary System

Interesting Features

  • Both kidneys filter about seven liters of blood plasma each hour to excrete only 35 milliliters of urine.
  • Conservation of useful metabolites is more useful function of kidneys than excretion of waste products.
  • Each kidney contains 1.2 millions of tiny tubules each contributing less than one micro liter of urine per hour.

Consumption of food not only furnishes important nutrients (such as carbohydrates, fats, proteins, vitamins and minerals) but also results in accumulation of undesirable and surplus products such as potassium. Similarly metabolism of food generates lot of toxic waste products such as urea, creatinine and hydrogen ion, excessive accumulation of which results in disease like situation. Renal system constantly and uninterruptedly exerts to eliminate these surplus and waste products through urine to keep the body in healthy state. In a day, about 170 liters of blood plasma is filtered by two kidneys in an adult man which includes most of desirable and undesirable metabolites. While passing through kidney most (99.5%) of volume and desirable metabolites are retained and only 1.5 liter of urine with undesirable excretory metabolites is eliminated.

Urinary System is meant for excretion of water soluble waste products arising out of metabolism. These waste products chiefly urea, creatinine, acids and electrolytes, if retained in body may lead to development of various disease and render the cells non-functional. The system comprises of a pair of kidneys and urinary tract, comprising of ureter (one pair), urinary bladder and urethra.


Last modified: Tuesday, 10 April 2012, 10:48 AM