19

Q1. Name the disorder in which glucose is present in excess quantities in urine.

Solution

Glycosuria

Q2. Name the branch of the renal artery which enters the glomerulus.

Solution

Afferent arteriole

Q3. Name the excretory organs found in the following organisms:

Earthworm

Liver fluke

Prawns

Cockroach

Solution

Animal Excretory Organs

Earthworm

Nephridia

Liver fluke

Flame cells

Prawns

Green/antennal glands

Cockroach

Malpighian tubules  

Q4. What activates the release of vasopressin from the neurohypophysis?  

Solution

Excessive loss of body fluid activates the release of vasopressin from the neurohypophysis.  

Q5. Name the three layers through which blood is filtered during glomerular filtration.  

Solution

Layers through which blood filters during glomerular filtration are    

Endothelium of glomerular blood vessels  

Epithelium of Bowman’s capsule  

Basement membrane present between the endothelium of the glomerulus and the epithelium of Bowman’s capsule  

Q6. What are ammonotelic animals? Give any two examples.

Solution

Animals which excrete nitrogenous waste products in the form of ammonia are called ammonotelic animals. Examples: Bony fish, aquatic insects

Q7. Name the three factors which activate the osmoreceptors in our body.

Solution

Three factors which activate the osmoreceptors in our body are

Blood volume

Body fluid volume

Ionic concentration

Q8. Draw a well-labelled diagram of the renal corpuscle.  

Solution

Renal corpuscle:        

Q9. Describe the structure of the Malpighian body.

Solution

The Malpighian body constitutes the glomerulus and Bowman’s capsule. The glomerulus is a tuft of blood capillaries. The afferent arteriole enters the glomerulus, while the efferent arteriole leaves the glomerulus. The Bowman’s capsule is a cup-shaped structure. The glomerulus is situated in the cup-shaped depression of the Bowman’s capsule.

Q10. State the function of rennin.

Solution

Renin stimulates the glomerular blood flow to bring the glomerular filtration rate back to normal.

Q11. Distinguish between uricotelism and ureotelism.  

Solution

Uricotelism     Ureotelism    

Waste products are excreted in the form of uric acid.  

Waste products are excreted in the form of urea.  

Elimination of uric acid requires less amount of water.  

Elimination of uric acid requires moderate amount of water.  

It is the least toxic substance.  

It is a moderately toxic substance.  

Reptiles, birds, insects and land snails exhibit uricotelism.  

Marine fish, mammals and terrestrial amphibians exhibit ureotelism.  

   

Q12. Draw a well-labelled diagram of the human urinary system.

Solution

Human urinary system:  

Q13. Name the notch present on the inner concave surface of the kidney.  

Solution

Hilum  

Q14. Name the part of the nephron which is situated in the medulla of the kidney.

Solution

Henle’s loop

Q15. Name the excretory organ of Planaria.

Solution

Flame cells

Q16. State in one line as to what happens in following disorders:

Renal calculi

Glomerulonephritis

Solution

Renal calculi - An insoluble mass of crystals of oxalates is formed in the kidneys.

Glomerulonephritis - Inflammation of glomeruli of the kidneys.

Q17. Where do you find the slit pores in the Bowman’s capsule?

Solution

Slit pores are present between the podocytes in Bowman’s capsule.

Q18. Name the hormones which play a crucial role in regulating the function of kidneys.

Solution

Renin, vasopressin, atrial natriuretic factor (ANF) and angiotensin I

Q19. Explain the renin-angiotensin mechanism.  

Solution

A fall in glomerular blood pressure activates the juxta glomerular cells to release renin.     Renin converts angiotensin, first to angiotensin I and then to angiotensin II.     Angiotensin II increases the glomerular blood pressure which increases the glomerular filtrate rate (GFR).     At the same time, angiotensin II activates the adrenal cortex to release aldosterone.     Aldosterone stimulates the reabsorption of sodium ions and water from DCT. This also results in an increase in GFR.  

Q20. How is urea formed in ureotelic animals?

Solution

In ureotelic animals, ammonia is converted into urea in the liver.  The urea formed is then released into the blood from where it is filtered and excreted by the kidneys.

Q21. Name any two substances present in the sebum.  

Solution

Sterols and wax  

Q22. Explain micturition.

Solution

The process of release of urine is called micturition. When the urinary bladder gets filled with urine, the stretch receptors present on the walls of the bladder send signals to the central nervous system (CNS). In response to these signals, CNS sends the motor message which causes the contraction of smooth muscles of the bladder and simultaneous relaxation of the urethral sphincters. This results in the release of urine from the body.

Q23. Name the neural mechanism responsible for micturition.  

Solution

Micturition reflex  

Q24. How is kidney stone formed?

Solution

Kidney stone is formed by the precipitation of uric acid and accumulation of oxalate crystals.

Q25. Name the network of the efferent arteriole formed around the renal tubule.

Solution

Peritubular capillaries

Q26. What is the significance of the hilum in the kidneys?

Solution

Ureters, blood vessels and nerves enter the kidneys at the hilum.

Q27. Explain how the glomerular filtration rate is maintained by the kidneys?  

Solution

Maintenance of the glomerular filtration rate is carried out by the juxtaglomerular apparatus in the kidneys.     It is the region formed by the close contact between the distal convoluted tubule and the afferent arteriole at a region.     When GFR falls, it stimulates JGA to release rennin.     Renin helps to bring reduced GFR back to normal.  

Q28. What is uraemia? Name and describe the process used to remove waste substances from individuals suffering from uraemia.

Solution

Uraemia is the accumulation of urea in the blood due to malfunctioning of the kidneys. In individuals suffering from uraemia, the waste substances are removed by haemodialysis. In this process, blood is drained from the convenient artery (usually radial artery), mixed with anticoagulant such as heparin and pumped into the dialysing unit. The dialysing unit consists of a coiled tube surrounded by a dialysing fluid. The dialysing unit has the same composition as that of the plasma membrane, but it does not contain any nitrogenous waste. The absence of nitrogenous water in the dialysing unit enables the easy movement of waste from urine into the tube through the porous membrane, thus clearing the blood from any waste. The cleared blood is then pumped back into the body through the same vein after adding anti-heparin.

Q29. Draw a well-labelled diagram of the L. S. of kidney. Label any six parts.

Solution

L. S. of kidney:  

Q30. Apart from the collection of the urine formed, what are the other functions performed by the collecting duct?

Solution

The collecting duct at times absorbs a large amount of water to produce concentrated urine. It allows some amount of urea to enter the medullary interstitium to maintain osmolarity. It secretes hydrogen and potassium ions to maintain pH and ionic balance of the blood.

Q31. State the function of sebum.

Solution

The sebum provides a protective oily covering which protects the skin.

Q32. Name the anticoagulant which is usually used in the haemodialysis process.  

Solution

Heparin  

Q33. A parrot and a dog were fed only a protein-rich diet. In what forms would they excrete nitrogenous wastes?

Solution

The parrot will excrete uric acid, while the dog will excrete urea.

Q34. Distinguish between ammonotelism and uricotelism.

Solution

Ammonotelism Uricotelism

Waste products are excreted in the form of ammonia.

Waste products are excreted in the form of uric acid.

Elimination of ammonia requires more water.

Elimination of uric acid requires less amount of water.

Aquatic amphibians, bony fish and aquatic insects exhibit ammonotelism.

Reptiles, birds, insects and land snails exhibit uricotelism.

 

Q35. Identify the regions of the renal tubules which absorb the following substances:     Urea, water, HCO₃⁻, K⁺  

Solution

Urea     Collecting duct     Water     Proximal convoluted tubule      HCO₃⁻      Proximal convoluted tubule      K⁺      Proximal convoluted tubule        

Q36. Name the excretory organs in fish.

Solution

Body surface and gills

Q37. State the function of protonephridia in amphioxus.  

Solution

Protonephridia in amphioxus maintain the ionic and fluid volume, i.e. protonephridia play an important role in osmoregulation.  

Q38. State the role of Henle’s loop in urine formation.

Solution

Henle’s loop maintains high osmolarity of the medullary interstitial fluid.

Q39. Name any two classes of uricotelic animals of the phylum Chordata.

Solution

Reptiles and birds

Q40. State the location of kidneys in the human body.

Solution

The kidneys are situated between the levels of the last thoracic and third lumbar vertebrae close to the dorsal inner wall of the abdominal cavity.