Urine Formation – 2
1. What is the full form of JGA?
A. Juxtaglomerular apparatus
B. Juxta glomerulus aperture
C. Juxta glial apparatus
D. Juxta glial aperture
Answer: A
Explanation: JGA stands for Juxtaglomerular apparatus. The kidneys have built-in mechanisms for the regulation of glomerular filtration rate. One such efficient mechanism is carried out by the juxtaglomerular apparatus.
2. JGA is formed by the cellular modifications of which of the following?
A. PCT
B. DCT
C. Convoluted tubule
D. Renal tubule
Answer: B
Explanation: Juxtaglomerular apparatus is a special sensitive region formed by the cellular modifications in the distal convoluted tubule and the afferent arteriole at the location of their contact.
3. A fall in the GFR activates which of the following cells?
A. PCT cells
B. Podocytes
C. DCT epithelium
D. JG cells
Answer: D
4. What is the GFR of a healthy individual?
A. 150 litres per day
B. 180 litres per day
C. 200 litres per day
D. 80 litres per day
Answer: B
Explanation: GFR in a healthy individual is approximately about 125 ml per minute, i.e., 180 litres per day. Although, the amount of urine secreted by a healthy individual differs significantly and is only about 1.5 litre per day.
5. Nearly 75% of the filtrate is reabsorbed by the renal tubules.
A. True
B. False
Answer: B
Explanation: Nearly 99 per cent of the filtrate that passes through our renal tubules every minute is being reabsorbed by our blood capillaries and the renal tubules themselves. Approximately 180 litres of filtrate is formed per day but only 1.5 litres of urine is released. Therefore, a huge amount of filtrate is being reabsorbed every minute.
6. What is reabsorption?
A. Absorption of the filtrate by the renal tubules
B. Secretion of nutrients by the filtrate
C. Absorption of retentate by the renal tubules
D. Absorption of proteins and carbohydrates only
Answer: A
Explanation: The absorption of the filtrate by the renal tubules is termed as reabsorption. The tubular epithelial cells in different segments of the nephron perform this either by active or passive mechanisms.
7. Which of the following substances are not reabsorbed actively by the nephrons?
A. Glucose
B. Amino acids
C. Sodium ions
D. Nitrogenous wastes
Answer: D
Explanation: Substances like glucose, amino acids, sodium ions, etc., in the filtrate, are reabsorbed actively whereas the nitrogenous wastes are absorbed by passive transport.
8. How is water reabsorbed in the initial segments of the nephrons?
A. By the active transport
B. By the passive transport
C. Water is not reabsorbed
D. Sometimes by active transport and sometimes by passive transport
Answer: B
Explanation: Reabsorption of water occurs passively in the initial segments of the nephron. During urine formation, the tubular cells secrete some substances into the filtrate to enhance the reabsorption process.
9. Which of the following substances are not secreted by the tubular cells?
A. H+ ions
B. K+ ions
C. Ammonia
D. Glucose
Answer: D
Explanation: During urine formation, the tubular cells secrete substances like H+, K+ and ammonia into the filtrate in the proximal convoluted tubule and the distal convoluted tubule.
10. What is the significance of the tubular secretion?
A. To maintain the hypotonic condition with the plasma
B. To maintain the hypertonic condition with the plasma
C. To maintain the ionic balance
D. To maintain the air pressure
Answer: C
Explanation: Tubular secretion is an important step of urine formation in our kidneys. Tubular secretion helps in the maintenance of the ionic balance of various electrolytes and ions that are present in our body fluids.
11. By which protein is the blood colloidal osmotic pressure maintained?
A. Albumin
B. Globulin
C. Haemoglobin
D. Myoglobin
Answer: A
Explanation: The blood colloidal osmotic pressure or the BCOP of the glomerulus is maintained by the protein albumin. It resists the filtration of fluid from the capillaries.
12. Net filtration pressure is equal to the glomerular hydrostatic pressure.
A. True
B. False
Answer: B
Explanation: Net filtration pressure of the glomerulus is equal to: Glomerular hydrostatic pressure – (Blood colloidal pressure + Capsular hydrostatic pressure)
It comes out equal to 10-15 mm Hg.
13. What does CHP stand for?
A. Capsular hydrostatic pressure
B. Capsid hydrated protein
C. Capsomere hydrated protein
D. Capsule hydrolysed protein
Answer: A
Explanation: CHP stands for Capsular hydrostatic pressure. It is the pressure caused by the filtrate or the fluid that reaches into Bowman’s capsule which resists filtration.
14. What is the condition of no urine formation called?
A. Oliguria
B. Polyuria
C. Diuresis
D. Anuria
Answer: D
Explanation: The condition of no urine formation is known as anuria. The condition of less urine formation is known as oliguria while excessive urine formation is known as polyuria.
15. What does CHP consist of?
A. Interstitial and artery pressure
B. Renal vein and artery pressure
C. Juxta medullary pressure and the arteriole pressure
D. Interstitial pressure and renal pressure
Answer: D
16. PCT is lined by which of the following cells?
A. Brush border columnar cells
B. Brush border cuboidal cells
C. Ciliated cuboidal cells
D. Ciliated columnar cells
Answer: B
17. In which renal tubule, the reabsorption is minimum?
A. Descending limb of Henle’s loop
B. Glomerulus
C. Collecting tubule
D. Ascending limb of Henle’s loop
Answer: D
Explanation: Reabsorption of water is minimum in ascending limb of Henle’s loop as it is impermeable to water which means that it does not allow the movement of water through itself.
18. The descending loop of Henle is impermeable to water.
A. True
B. False
Answer: B
Explanation: The descending limb of the loop of Henle is permeable to water. It means that water can easily pass the loop. But the descending limb is almost impermeable to electrolytes which means it does not allow the movement of electrolytes through itself.
19. How does the ascending loop of Henle allow the movement of electrolytes?
A. Only active transport
B. Only passive transport
C. By both active and passive transport
D. Only by diffusion
Answer: C
Explanation: The ascending limb of Henle’s loop is impermeable to water but allows the transport of electrolytes actively or passively. Moreover, the width of this tubule also varies as it has a thin segment and a thick segment of the ascending limb.
20. What happens when the filtrate passes through the ascending loop of Henle?
A. It gets dilute
B. It gets concentrated
C. No effect
D. It reverts back
Answer: A
Explanation: As the ascending limb is impermeable to water, therefore as the concentrated filtrate from the descending limb passes upwards, then it gets diluted due to the passage of electrolytes to the medullary fluid.
21. Which of the following is reabsorbed completely in the PCT?
A. Amino acids
B. Glucose
C. Ascorbic acid
D. Sodium ions
Answer: B
Explanation: Glucose is reabsorbed completely in the PCT by active transport. 70-80% of water is reabsorbed by osmosis while 70% sodium, potassium, and calcium ions are actively transported.
22. Is the nephric filtrate present in which segment of the renal tubule is isotonic to plasma?
A. Collecting duct
B. Collecting tubule
C. PCT
D. DCT
Answer: C
Explanation: The nephric filtrate present in the PCT is isotonic to blood plasma i.e. 300 mOsmol/L. In PCT, there is obligatory reabsorption of water, i.e., absorption without the influence of any hormone.
23. Which of the following does not show maximum osmolarity?
A. Tip of Henle’s loop
B. Interstitial fluid
C. PCT
D. Collecting duct
Answer: C
Explanation: The tip of Henle’s loop, interstitial fluid, and collecting duct show maximum osmolarity i.e. 1200 mOsmol/L. All of these structures are present in the inner medullary regions of the kidney.
24. If the loop of Henle is removed, hypertonic urine will be produced.
A. True
B. False
Answer: B
Explanation: If the loop of Henle is removed, hypotonic urine will be produced as water will not be reabsorbed as in descending Henle’s loop, 5-10% of the water reabsorption takes place.
25. On which segment onwards, the nephric filtrate is called as urine?
A. DCT
B. PCT
C. Collecting duct
D. Glomerulus
Answer: A
Explanation: DCT onwards, the nephric filtrate is called urine. In the last part or segment of the collecting duct, almost 99 per cent of the reabsorption of nephric filtrate has taken place.
26. The passage of which of the following makes the urine hypertonic?
A. Sodium ions
B. Urea
C. Glucose
D. Potassium ions
Answer: B
27. What is the normal amount of urea in the blood?
A. 10-15 mg/100 ml
B. 18-38 mg/100 ml
C. 40-50 mg/100 ml
D. 0.2-0.5 mg/100 ml
Answer: B
Explanation: The normal amount of urea present in the blood is 18-38 mg/100 ml of the blood. The increase in the amount of urea in the blood is termed as uremia.
28. What is the percentage of urea present in the urine?
A. 96%
B. 0.2%
C. 2%
D. 5%
Answer: C
