Question

The filtration units of kidney are called ____________.

• A. Ureter
• B. Urethra
• C. Neurons
• D. Nephrons

Answer 1

The correct option is D Nephrons

Hint: Every living organism generates waste in its body and has a mechanism to expel it. In humans, the excretory system eliminates waste as urine.

Part 1: Definition - Human Excretory System

• In humans, the excretory system takes care of waste generation and elimination.
• It comprises of the following structures:

2 Kidneys

2 Ureters

1 Urinary bladder

1 Urethra

Part 2 - Role of the kidney in urine formation

• Kidneys are the primary organ of the human excretory system.
• The kidneys remove waste products called urea along with extra water and ions from the blood to form urine through tiny filtering units called nephrons.
• The nephron is the functional unit of a kidney.

• Each kidney consists of millions of nephrons.

Part 3 - Structure of nephron

• All nephrons function together to filter blood and expel waste products.
• A nephron consists of the following parts:

Bowman’s capsule - It is the first part of the nephron. Glomerular filtration occurs here.

Proximal Convoluted Tubule - Water and reusable materials from the blood are now reabsorbed back into it.

The loop of Henle - Urine becomes concentrated in this area.

Distal Convoluted Tubule and Collecting Duct - Here the kidney hormones cause their effect.

• The collecting ducts together form the renal pelvis. Through the renal pelvis, the urine passes into the ureter and then into the bladder.
  

Part 4 - Conclusion

• From the above discussion, we can conclude that urine is filtered and concentrated in nephrons and then collected to excrete out of the body.

Final step: The filtration units of kidney are called as nephrons.