Biology · Excretory Products and Their Elimination · NEET
Four organs, in a 2-2-1-1 pattern: a PAIR of kidneys (2), a PAIR of ureters (2), ONE urinary bladder (1), and ONE urethra (1). NCERT states this exact line, so learn the counts. A common exam slip is thinking there are two bladders or two urethras — there is only one of each.
They sound similar but are different tubes. Each URETER carries urine FROM a kidney TO the urinary bladder (there are two ureters). The URETHRA carries urine FROM the bladder OUT of the body (there is only one). Memory tip: ureTER goes To the tank (bladder); urethra is the exit.
The kidneys sit between the last thoracic and the third lumbar vertebra, close to the dorsal (back) inner wall of the abdominal cavity. They are placed slightly toward the back, not in the belly cavity space with the intestines. This position is why kidney surgery is often done from the back side.
Each kidney is reddish-brown and bean-shaped. In an adult it is 10–12 cm long, 5–7 cm wide, and 2–3 cm thick, with an average weight of 120–170 g. These exact numbers are directly asked in NEET, so memorise the ranges.
The hilum is a notch at the centre of the inner concave surface of the kidney. Through the hilum, the ureter, the blood vessels (renal artery and renal vein), and the nerves enter or leave the kidney. If a question asks what passes through the hilum, the answer is these three: ureter, blood vessels, and nerves.
The urinary bladder STORES urine. Urine formed by the nephrons flows through the ureters into the bladder, where it stays until a voluntary signal from the CNS releases it. The release of stored urine is called micturition. So in match-type questions: 'storage of urine' always pairs with the urinary bladder.
Match the items in Column I (Function) with Column II (Part of Excretory system): a. Ultrafiltration b. Concentration of urine c. Transport of urine d. Storage of urine | i. Henle's loop ii. Ureter iii. Urinary bladder iv. Malpighian corpuscle v. Proximal convoluted tubule
Try the real previous-year questions from this chapter — each with the answer and a full solution.
A pair of kidneys, a pair of ureters, one urinary bladder, and one urethra. The kidneys form urine, ureters transport it, the bladder stores it, and the urethra removes it from the body.
The kidneys form urine. Each kidney contains nearly one million nephrons, the functional units, where blood is filtered and urine is made.
The urethra carries urine out of the body from the bladder. The ureters only carry urine from the kidneys to the bladder.
An adult human kidney weighs about 120–170 g on average, is 10–12 cm long, 5–7 cm wide, and 2–3 cm thick.
The ureter, the blood vessels (renal artery and vein), and the nerves enter or leave the kidney through the hilum, a notch on its inner concave surface.
