Explained in short about four organs …

Kidneys: They are a pair of bean-shaped, reddish brown organs that help in maintaining the water and salt concentration of blood by the process of osmoregulation.

Ureters: They carry urine from each kidney to the urinary bladder.

Urinary bladder: They store urine until it is expelled from the body.

Urethra: It is a short tube through which urine is passed out.

(a) In humans, the excretory system consists of a pair of kidneys, a pair of ureters, urinary bladder and urethra.

(b) Kidneys are two bean shaped organs lying at the back of the abdomen, one on either side of the vertebral column. Waste products from the blood and urine are removed by the kidney.

(c) A Nephron is the basic filtration unit of the kidney. It is a cluster of thin walled blood capillaries.

(d) The urine produced by filtering the blood is transported to the urinary bladder. This is done by a pair of ureters. Ureters are long muscular tubes.

(e) Urinary bladder is a muscular bag like structure which can hold urine. The urinary bladder is under the control of nerves. When the bladder is full one get urge to urinate.

(f) This urine is thrown out of the body through urethra.

(g) Apart from the kidney, the skin and lungs are also helpful in the excretion.