Excretory System — Set 5
Biology · उत्सर्जन तंत्र · Questions 41–50 of 50
Where are the kidneys located relative to the peritoneum?
Correct Answer: A. Retroperitoneal
Kidneys are located behind the peritoneal lining of the abdominal cavity. This position is technically described as retroperitoneal. They are situated at the level of the T12 to L3 vertebrae.
Which part of the nephron is impermeable to water?
Correct Answer: C. Ascending limb of Henle
The thick ascending limb of the loop of Henle is impermeable to water but allows salt transport. This helps create the high salt concentration in the surrounding medulla. The descending limb, conversely, is highly permeable to water.
What is the name of the specialized cells that wrap around glomerular capillaries?
Correct Answer: A. Podocytes
Podocytes are epithelial cells of Bowman's capsule with foot-like projections called pedicels. They form filtration slits that allow small molecules to pass into the capsule. These slits are a crucial part of the ultrafiltration barrier.
What is the name of the condition where there is a lack of urine production?
Correct Answer: D. Anuria
Anuria is defined as the total suppression or absence of urine formation. It is often a medical emergency indicating complete kidney failure or a major obstruction. Oliguria refers to a significantly reduced urine output.
Which enzyme is released by the kidney to initiate the RAAS pathway?
Correct Answer: A. Renin
Renin is secreted by the juxtaglomerular cells in response to low blood pressure. It acts on angiotensinogen to produce angiotensin I. This is a critical regulatory step for systemic hemodynamics.
Which gas is excreted by the skin in very minute quantities?
Correct Answer: A. Carbon dioxide
The correct answer is 'Carbon dioxide'. While the lungs are the main organ for gas excretion, the skin also releases tiny amounts of CO2. This occurs through simple diffusion across the skin surface. However, this is negligible compared to pulmonary respiration.
Which part of the nephron is also known as the Malpighian body?
Correct Answer: D. Renal corpuscle
The renal corpuscle, consisting of the glomerulus and Bowman's capsule, is also called the Malpighian body. It is the site where the primary filtration of blood takes place. It should not be confused with Malpighian tubules found in insects.
What is the typical length of a human kidney?
Correct Answer: B. 10-12 cm
An average adult kidney is about 10-12 cm in length and 5-7 cm in width. It weighs approximately 120 to 170 grams in a healthy adult. The right kidney is usually slightly lower than the left one due to the liver.
Which metabolic byproduct gives the characteristic ammonia-like smell to stale urine?
Correct Answer: C. Urea breakdown
When urine is left standing, bacteria convert urea back into ammonia. This process is what causes the pungent odor of stale urine. Freshly passed urine normally has a faint, slightly aromatic odor.
Which type of epithelium lines the inner surface of the urinary bladder?
Correct Answer: D. Transitional
Transitional epithelium is a specialized tissue that can stretch and change shape. It allows the bladder to expand as it fills with urine without tearing. This epithelium is also found in the ureters and part of the urethra.