Excretion for class 10th

Q 1 Define excretion.
A The process of removal of metabolic waste like urea ,uric acid ,ammonia ,extra water ,salts etc is called excretion

Q2 Does lungs  also help in excretion ?
A yes ! they remove carbon dioxide but they are not only doing excretion exclusively therefore they are called respiratory organs not excretory.

Q3 What is the structure of Kidney ?
A there is a pair of kidneys present in both sides of our  abdomen .Each kidney gets blood from heart through renal artery (oxygenated but full of metabolic waste)whereas the vessel which takes blood away from heart is called renal vein(de oxygenated but free of metabolic waste).The blood when enters in kidney is filtered in tiny units called nephron (one million in each kidney).The nitrogenous waste is collected in the form of urine in the urinary bladder through a tube like structure called ureter.From time to time this urine is excreted out of the body.