Describe the structure of a human kidney with the help of a labelled diagram.
Humans have of a pair of kidneys which are reddish brown, bean shaped structures situated between the levels of last thoracic and third lumbar vertebrae close to the dorsal inner wall of the abdominal cavity. Each kidney of an adult human measures 10-12 cm in length, 5-7 cm in width, 2-3 cm in thickness with an average weight of 120-170 gm. There is present a notch called hilum towards the centre of the inner concave surface of the kidney. Through the hilum, ureter, blood vessels and nerves enter. Inner to the hilum, is a broad funnel shaped space called the renal pelvis with projections called calyces. The layer on the outside of the kidney is a tough capsule. Inside the kidney, there are two zones, an outer cortex and an inner medulla. The medulla is divided into a few conical masses called medullary pyramids projecting into the calyces. The cortex extends in between the medullary pyramids as renal columns called columns of Bertin. The medullary pyramids are connected with minor calyces (sine, calyx) which in turn lead into major calyces. A human kidney possesses two to three major calyces. Major calyces open into renal pelvis which in turn leads to ureter. A kidney has about ten lakh nephrons. A longitudinal section of a human kidney in diagrammatic view is as follows:
Fill in the blanks appropriately.
Organ Excretory wastes
(a) Kidneys ______________
(b) Lungs ______________
(c) Liver ______________
(d) Skin ______________
Match the items of column I with those of column II.
Column I Column II
(a) Ammonotelism (i)Birds
(b) Bowman’s capsule (ii)Water reabsorption
(c) Micturition (iii)Bony fish
(d) Uricotelism (iv)Urinary bladder
(e) ADH (v)Renal tubule
Mention the substances that exit from the tubules in order to maintain a concentration gradient in the medullary interstitium.
Fill in the gaps.
(a) Ascending limb of Henle’s loop is________to water whereas the descending limb is________to it.
(b) Reabsorption of water from distal parts of the tubules is facilitated by hormone________
(c) Dialysis fluid contains all the constituents as in plasma except________
(d) A healthy adult human excretes (on an average)________gm of urea/day.
Indicate whether the following statements are true or false.
(a) Micturition is carried out by a reflex.
(b) ADH helps in water elimination, making the urine hypotonic.
(c) Protein-free fluid is filtered from blood plasma into the Bowman’s capsule.
(d) Henle’s loop plays an important role in concentrating the urine.
(e) Glucose is actively reabsorbed in the proximal convoluted tubule.
Sort the following into actively or passively transported substances during reabsorption of GFR. glucose, aminoacids, nitrogenous wastes, Na+, water
The glomerular filtrate in the loop of Henle gets concentrated in the descending limb and then gets diluted in the ascending limb. Explain.
How does tubular secretion help in maintaining ionic and acid-base balance in body fluids?
The following abbreviations are used in the context of excretory functions, what do they stand for?
(a) ANF (b) ADH
(c) GFR (d) DCT
Name the following.
(a) A chordate animal having flame cells as excretory structures.
(b) Cortical portions projecting between the medullary pyramids in the human kidney.
(c) A loop of capillary running parallel to the Henle’s loop.
Complete the following:
(a) Urinary excretion = Tubular reabsorption +Tubular secretion ________
(b) Dialysis fluid = Plasma ________
What is the procedure advised for the correction of extreme renal failure? Give a brief account of it.
Aquatic animals generally are ammonotelic in nature whereas terrestrial forms are not. Comment.
Draw a labelled diagram showing reabsorption and secretion of major substances at different partsof the nephron.