The normal value of GFR is approximately
(a) 650 ml/min
(b) 180 ml/min
(c) 180 ml/day
(d) 125 ml/min
It can also be translated as about 180 L/day.
What is used as an osmolyte in human beings to increase medullary interstitial osmolality during concentration of urine ?
3. Both a and b
4. Uric acid
Urea is relatively less toxic than ammonia and thus can be stored and used to increase the osmolality of body fluids.
The blood from the glomerulus is carried away by:
1. Afferent arteriole
2. Efferent arteriole
3. Peritubular capillary network
4. Renal vein
Read page 292,XI NCERT
Vasa recta in cortical nephrons :
1. Arises from afferent arteriole rather that efferent arteriole
2. Does not get involved in counter current exchange with loop of henle
3. Carries deoxygenated blood rich in urea
4. Is absent or highly reduced
Read page 293, Xl NCERT
The proximal convoluted tubule is lined by the:
1. Simple cuboidal epithelium
2. Simple columnar epithelium
3. Simple cubodial brush bordered epithelium
4. Simple columnar brush bordered epithelium
Read page 294, Xl NCERT
During concentration of urine by the human kidneys, NaCl is returned to the medullary interstitium by the:
(a) Descending limb of the loop of Henle
(b) Ascending limb of the loop of Henle
(c) Descending limb of the vasa recta
(d) Ascending limb of the vasa recta
Read page 296, XI NCERT
Identify the correct statement regarding the excretion of acids by the human kidney :
1. The filtered bicarbonate is absorbed by anion transport
2. The intercalated cells of the distal tubule secrete hydrogen ions to reabsorb bicarbonate from the tubular fluid.
3. All of the filtered bicarbonate is normally reabsorbed in the first half of the distal tubule.
4. Urine pH is normally greater than that of plasma.
Filtered bicarbonate is reabsorbed following hydrogen ion secretion by the renal tubules. This converts the bicarbonate to carbonic acid, which dissociates to form water and CO2, both of which pass across the apical membrane of the tubular cells before reforming bicarboate ions. Most of the filtered bicarbonate is reabsorbed in the first half of the proximal tubule. Urine pH is normally less than that of plasma.
Blood doping means use of banned substances by athletes that have a favorable effect on erythrocyte count by stimulating the bone marrow. The source of such a hormone can be the human:
Kidney produces erythropoietin that stimulates bone marrow to produce more RBCs.
The main disadvantage of urea as an excretory product for animals eliminating it would be:
1. its high toxicity
2. Needs lot of water to be eliminated
3. It being an osmolyte
4. Energy expenditure to produce it
Urea is less toxic than ammonia, needs less water to be eliminated and its use as an osmolyte is actually an advantage during concentration of urine.
Match each item in Column I with one in Column II and choose the correct option from the codes given below:
A B C
1. b d f
2. a d f
3. a c e
4. b d e
Factual:- Filtration fraction is 125[GFR] / 660[Renal plasma flow].