Punjab State Board PSEB 11th Class Biology Important Questions Chapter 19 Excretory Products and their Elimination Important Questions and Answers.
PSEB 11th Class Biology Important Questions Chapter 19 Excretory Products and their Elimination
Very short answer type questions
Write the mode of excretion performed by Xenopus.
Dual excretion (mainly ammonotelism and partly ureotelism).
In which of the organism antennary glands are found as excretory organ?
What is the excretory product from the kidney of reptiles? [NCERT Exemplar]
Give the name of vessel of peritubular capillaries that runs parallel to the loop of Henle.
Give the name of the reservoir of urine in the body.
Give the name of cells that are responsible for the formation of filtration slits or slit pores.
Podocytes (epithelial cells of Bowman’s capsule).
In which part of excretory system of mammals you can first use the term urine?
The filtrate formed by the process of ultrafiltration in the Bowman’s capsule is called glomerular filtrate or primary urine.
What is the ratio of the concentrated filtrate to that of the initial filtrate?
The concentrated urine (filtrate) is nearly four times concentrated than the initial filtrate formed.
What will be the effect on the amount of urine released when water is abundant in the body tissues in case of vertebrates?
Vertebrates excrete large quantities of dilute urine when water is abundant in the body tissues and vice-versa.
What is the pH of urine? [NCERT Exemplar]
It ranges from 4.5-8.2, average pH is 6.0.
What are the two substances responsible for causing the gradient for increasing hyperosmolarity of medullary interstitium?
NaCl and urea.
Give the name of the main component that play an important role in the counter-current mechanism.
Henle’s loop and vasa recta.
Short answer type questions
Describe the structure of human kidney.
- Shape and Size of Kidney: 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 g.
- Structure of Kidney: Towards the centre of the inner concave surface of the kidney is a notch called hilum through which ureter, blood vessels and nerves enter.
- Inner Structure: Inner to the hilum is a broad funnel-shaped space called the renal pelvis with projections called calyces. The outer layer of 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 (medullary pyramids) projecting into the calyces. The cortex extends in between the medullary pyramids as renal columns called Columns of Bertini.
What is the function of proximal convoluted tubules in the kidney?
Function of Proximal Convoluted Tubule (PCT): PCT is lined by simple cuboidal brush border epithelium which increases the surface area for reabsorption. Nearly all of the essential nutrients, and 70-80 percent of electrolytes and water are reabsorbed by this segment. PCT also helps to maintain the pH and ionic balance of the body fluids by selective secretion of hydrogen ions, ammonia and potassium ions into the filtrate and by absorption of HCO from it.
What is the function of Henle’s loop?
Function of Henle’s Loop: Reabsorption in this segment is minimum. However, this region plays a significant role in the maintenance of high osmolarity of medullary interstitial fluid. The descending limb of loop of Henle is permeable to water but almost impermeable to electrolytes. This concentrates the filtrate as it moves down. The ascending limb is impermeable to water but allows transport of electrolytes actively or passively. Therefore, as the concentrated filtrate pass upward, it gets diluted due to the passage of electrolytes to the medullary fluid.
What is the function of distal convoluted tubule?
Function of Distal Convoluted Tubule (DCT): Conditional reabsorption of Na+ and water takes place in this segment. DCT is also capable of reabsorption of HCO and selective secretion of hydrogen and potassium ions and NH3 to maintain the pH and sodium-potassium balance in blood.
What is the function of collecting duct?
- Large amounts of water could be reabsorbed from this region.
- This segment also allows the transport of small amounts of urea into the medullary interstitium, to maintain the osmolarity.
- It also plays a role in maintaining pH and ionic balance of the body fluids by selective section of K+ and H+ ions.
How does reabsorption take place in the excretory system in human?
Reabsorption: A comparison of the volume of the filtrate formed per day (180 litres per day) with that of the urine released (1.5 litres), suggest that nearly 99 per cent of the filtrate has to be reabsorbed by the renal tubules. This process is called reabsorption. The tubular epithelial cells in different segments of nephron perform this either by active or passive mechanisms. For example, substances like glucose, amino acids, Na+, etc., in the filtrate are reabsorbed actively whereas the nitrogenous wastes are absorbed by passive transport. Reabsorption of water also occurs passively in the initial segments of the nephron. During urine formation, the tubular cells secrete substances like H+, K+ and ammonia into the filtrate. Tubular secretion is also an important step in urine formation as it helps in the maintenance of ionic and acid base balance of body fluids.
Which gland releases ADH? What is the role of ADH in excretion?
Hypothalamus releases ADH. ADH facilitates water reabsorption from latter part of tubules. This prevents diuresis. Excess fluid loss, through urine is called diuresis.
Write a short note on-disorders of the excretory system.
Disorders of the Excretory System
The disorders related to kidneys are :
- Renal calculi and
Hemodialysis is the process of removal of nitrogenous wastes from the blood of a uremia patient.
Kidney transplantation is the ultimate method of correcting urinary failure, in which a functioning kidney from a suitable donor is transplanted.
- Blood from the artery of an uremia patient is taken, cooled to 0°C and mixed with an anticoagulant like heparin.
- It is put into the cellophane tubes of the artificial kidney, where cellophane is permeable to micromolecules, but not to macromolecules like plasma protein.
- Outside the cellophane tube is the dialysing fluid, which has the same composition as that of plasma except the nitrogenous molecules like urea, uric acid, creatine, etc.
- Hence, the nitrogenous molecules from within the cellophane tubes flow into the dialysing fluid, following concentration gradient, (dialysis)
- The blood coming out of the artificial kidney is warmed to body temperature, mixed with antiheparin and restored to a vein of the patient.
Long answer type questions
The glomerular filtrate in the loop of Henle gets concentrated in the descending and then gets diluted in the ascending limbs. Explain. [NCERT Exemplar]
- The gradient of increasing hyperosmolarity of medullary interstitium is maintained by a counter current mechanism and the proximity between the Henle’s loop and vasa recta.
- This gradient is mainly caused by NaCl and urea. The transport of these substances facilitated by the special arrangement of Henle’s loop and vasa recta is called the counter current mechanism.
- NaCl is transported by the ascending limb of Henle’s loop, which is exchanged with the descending limb of vasa-recta. NaCl is returned to the medullary interstitium by the ascending part of vasa recta.
- But, contrarily, the water diffuses into the blood of ascending limb of vasa recta and is carried away into the general blood circulation.
- Permeability to urea is found only in the deeper parts of thin ascending limbs of Henle’s loops and collecting ducts. Urea diffuses out of the collective ducts and enters into the thin ascending limb.
- A certain amount of urea recycled in this way is trapped in medullary interstitium by the collecting tubule. This mechanism helps in the maintenance of a concentration gradient in the medullary interstitium.
- Presence of such gradient helps in an easy passage of water from the collecting tubule, resulting in the formation of concentrated urine (filtrate) i.e., nearly four times concentrated than the initial filtrate formed.