This set of Biology Written Test Questions for AIIMS Exam focuses on “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
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?
c) Convoluted tubule
d) Renal tubule
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
c) DCT epithelium
d) JG cells
Explanation: A fall in the GFR can activate the JG cells to release renin which can stimulate the glomerular blood flow and thereby the GFR back to normal.
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
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.
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
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?
b) Amino acids
c) Sodium ions
d) Nitrogenous wastes
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
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
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
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?
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.
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
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?
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
Explanation: CHP or Capsular hydrostatic pressure consists of Interstitial pressure and renal pressure. Both of these pressures act opposite to the glomerular hydrostatic pressure.
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