Excretory Product AND Their Elimination flash cards

1. 1.What is excretion?

   Excretion is the process of removal of harmful metabolic nitrogenous wastes and other unwanted substances from the body to maintain homeostasis.

   Hint: Removal of metabolic wastes

2. 2.Name the major nitrogenous excretory products in animals.

   The three major nitrogenous wastes are ammonia, urea and uric acid. They differ in toxicity and water requirement for elimination.

   Hint: Three N-containing wastes

3. 3.Which nitrogenous waste is the MOST toxic and requires the MOST water for elimination?

   Ammonia is the most toxic and needs the largest amount of water for its excretion.

   Hint: Most soluble, most toxic

4. 4.Which nitrogenous waste is the LEAST toxic and needs the LEAST water?

   Uric acid is the least toxic and is excreted with minimum loss of water (as a paste or pellet).

   Hint: Least toxic; water conserved

5. 5.Define ammonotelism.

   Ammonotelism is the mode of excretion in which ammonia is the chief excretory product. It is common in bony (teleost) fishes, aquatic amphibians and aquatic insects.

   Hint: Ammonia excreters

6. 6.How is ammonia mainly removed in ammonotelic aquatic animals?

   Ammonia, being highly soluble, is generally excreted by diffusion across body surfaces or gill surfaces as ammonium ions; little is lost via the kidney.

   Hint: Diffusion through gills/body surface

7. 7.Define ureotelism.

   Ureotelism is excretion in which urea is the main nitrogenous waste. Seen in mammals, many terrestrial amphibians and marine fishes.

   Hint: Urea excreters

8. 8.Where is urea synthesised, and what happens to it?

   Ammonia produced by metabolism is converted into less toxic urea in the liver (ornithine/urea cycle); it is released into the blood, filtered and excreted by the kidneys.

   Hint: Made in liver, cleared by kidney

9. 9.Define uricotelism.

   Uricotelism is excretion in which uric acid is the main waste, removed as a pellet/paste with very little water. Seen in reptiles, birds, land snails and insects.

   Hint: Uric acid; water-conserving terrestrials

10. 10.QUESTION: Birds and reptiles are uricotelic. What is the adaptive advantage of this?

    Uric acid is least toxic and needs minimal water for excretion, so it conserves water — advantageous for terrestrial life and for cleidoic (shelled) eggs where waste must be stored without harming the embryo.

    Hint: Water conservation + shelled egg

11. 11.How does the human excretory system's basic organs list read?

    It consists of a pair of kidneys, a pair of ureters, a urinary bladder and a urethra.

    Hint: Kidneys, ureters, bladder, urethra

12. 12.Where are the kidneys located in humans?

    Kidneys are reddish-brown, bean-shaped organs situated between the levels of the last thoracic and third lumbar vertebra, near the dorsal inner wall of the abdominal cavity.

    Hint: Last thoracic to 3rd lumbar

13. 13.What are the approximate dimensions and weight of a human kidney?

    Each kidney is about 10-12 cm long, 5-7 cm wide, 2-3 cm thick, weighing around 120-170 g in an adult.

    Hint: ~10-12 cm; ~120-170 g

14. 14.What is the hilum of the kidney?

    The hilum is a notch on the inner (concave) surface of the kidney through which the ureter, blood vessels and nerves enter and leave.

    Hint: Notch for vessels/ureter

15. 15.Name the outer and inner zones of the kidney seen in section.

    The outer zone is the cortex and the inner zone is the medulla. The cortex extends between the medullary pyramids as the columns of Bertini.

    Hint: Cortex + medulla

16. 16.What is the renal pelvis and what are its projections called?

    Inner to the hilum is a broad funnel-shaped space, the renal pelvis, with projections called calyces that collect urine from the pyramids.

    Hint: Funnel space with calyces

17. 17.What are medullary pyramids (renal pyramids)?

    The medulla is divided into a few conical masses called medullary pyramids, which project into the calyces and carry urine toward the pelvis.

    Hint: Conical medullary masses

18. 18.What is the columns of Bertini?

    The columns of Bertini are extensions of cortical tissue that project inward between the medullary pyramids.

    Hint: Cortex between pyramids

19. 19.What is the nephron?

    The nephron is the structural and functional unit of the kidney. Each kidney has about one million (10 lakh) nephrons.

    Hint: Functional unit; ~1 million/kidney

20. 20.What are the two main parts of a nephron?

    Each nephron has a glomerulus (Malpighian corpuscle region) and a renal tubule.

    Hint: Glomerulus + renal tubule

21. 21.What is the glomerulus?

    The glomerulus is a tuft of capillaries formed by the afferent arteriole; blood leaves it through the efferent arteriole. It is the site of filtration.

    Hint: Capillary tuft; afferent in, efferent out

22. 22.What is the Malpighian body / renal corpuscle?

    The renal corpuscle (Malpighian body) = glomerulus + Bowman's capsule together. It is the filtering unit at the start of the nephron.

    Hint: Glomerulus + Bowman's capsule

23. 23.What is Bowman's capsule?

    Bowman's capsule is the double-walled cup-like beginning of the renal tubule that encloses the glomerulus and receives the filtrate.

    Hint: Cup enclosing glomerulus

24. 24.List the parts of the renal tubule in order after Bowman's capsule.

    Bowman's capsule → Proximal Convoluted Tubule (PCT) → Loop of Henle (descending + ascending limbs) → Distal Convoluted Tubule (DCT) → collecting duct.

    Hint: PCT → Loop → DCT → CD

25. 25.What are the two types of nephrons based on location?

    Cortical nephrons — loop of Henle is very short, extends only slightly into medulla; Juxtamedullary nephrons — loop of Henle runs deep into the medulla.

    Hint: Cortical vs juxtamedullary

26. 26.Which nephron type is important for producing concentrated urine?

    Juxtamedullary nephrons, whose long loops of Henle extend deep into the medulla, are important for the counter-current mechanism and concentrating urine.

    Hint: Long-looped, deep medulla

27. 27.What is the vasa recta?

    The vasa recta is a network of capillaries running parallel to the loop of Henle. It is well developed in juxtamedullary nephrons and important in counter-current exchange.

    Hint: Capillary parallel to loop

28. 28.In cortical nephrons, how is the vasa recta?

    In cortical nephrons the vasa recta is absent or highly reduced.

    Hint: Reduced/absent in cortical

29. 29.What are the three main processes of urine formation?

    1. Glomerular filtration, 2. Reabsorption, and 3. Secretion (tubular secretion).

    Hint: Filtration, reabsorption, secretion

30. 30.What is glomerular filtration (ultrafiltration)?

    It is the filtration of blood at the glomerulus in which water and small solutes pass into Bowman's capsule while blood cells and large proteins are retained; called ultrafiltration because it is a fine, non-selective pressure filtration.

    Hint: Non-selective pressure filtration

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