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EXCRETORY PRODUCTS AND THEIR ELIMINATION

IMPORTANT TERMS:

 v  ADH: Antidiuretic hormone released from posterior pituitary and acts on DCT and collecting duct to make them more permeable to water.

v  Ammonotelism: The phenomenon of urinary elimination of nitrogenous wastes mainly in the form of ammonia.
v  Ammonotelic Animals: The animals which excrete ammonia as the main nitrogenous waste in the urine eg. Most teleost fishes, tadpoles and aquatic insects.
v  Bowman’s Capsule: Cup shaped double walled structure enclosing glomerulus.
v  Dialysis: The process of separating small solute molecules from macro-molecular colloids, using a selectively permeable membrane.
v  Flame Cells: Excretory organs in flat worms.
v  Glomerular Filtrate: A protein free filtrate produced in Bowman’s capsule.
v  Green Glands (Antenal Glands): Excretory organs of crustaceans such as prawn.
v  Hemodialysis: The process of removal of excess urea from the blood of a patient (generally suffering from uremia) using an artificial kidney.
v  Hypotonic Urine: Urine with concentration less than blood plasma.
v  Hypertonic Urine: Urine with concentration higher than blood plasma.
v  Malpighian Tubules: Excretory organs in cockroach.
v  Micturition: Process of voiding urine.
v  Nephridia: Excretory organs in Annelids.
v  Nephron: Structural and functional unit of kidney.
v  Nephritis: Refers to the inflammation of glomerulus of nephron.
v  Osmoregulation: Process by which water content and ion concentration is regulated in the cells/body.
v  Osmoconformers: Animals that change the osmolarity of their body fluids according to the osmolarity of the ambient medim, eg., all marine invertebrates and some fresh water invertebrates.
v  Osmoregulators: Animals that maintain the internal osmolarity different from the surrounding medium, eg., most vertebrate, (exception, hag fish, sharks and rays).
v  Osmolarity: The total solute concentration of a system. It is expressed as moles of solute per litre of solution (i.e., milliosmole per litre or mosom L-1).
v  Ureotelism: The phenomenon of urinary elimination of nitrogenous wastes mainly in the form of urea.
v  Ureotelic Animals: The animals which excrete urea as the main nitrogenous waste in the urine, e.g., mammals adult amphibians, turtles.
v  Uricotelism: The phenomenon of urinary elimination of nitrogenous wastes mainly in the form of uric acid.
v  Uricotelic Animals: The animals which excrete uric acid as the main nitrogenous waste in the urine,e.g., land snails, insects, birds and many reptiles.

 

 

                                            ADDITIONAL  INFORMATION :

v  Kidney Types:

(i) Archinephric kidney (ancestral kidney): It is believed that the primitive vertebrate ancestor had this type of kidney, such a type of kidney is found today in the larvae of certain cyclostomes (e.g., myxine) but do not occur in any adult vertebrate.

(ii) Pronephric kidney: It is also called anterior kidney due to its anterior position. It appears as an embryonic functional kidney in cyclostomes, fishes and amphibians. It is non-functional in the embryonic life of reptiles, birds and mammals. It is retained throughout life in adult cyclostomes and a few bony fishes.

(iii) Mesonephric kidney: It is also called middle kidney. It is functional both in embryo as well as adults in case of lamprey, most fishes and amphibians, while in reptiles, birds and mammals, it is functional in embryo stage, but is replaced by metanephric kidney in the adults.

In sharks and caecilians (limbless amphibians) tubules extend posteriorly throughout the length of coelom, such a kidney is called opistonephric kidney.

(iv) Metanephric Kidney: It is also called posterior kidney. Such kidneys are found in adult amniotes (reptiles birds and mammals). Such kidneys have large number of nephrons with well developed glomeruli.

v   Nephrology: Study of the structure, working and disorders of the kidneys.

v   Urology: Study of the female urinary tract and the male urogenital tract.

v   Urothiology: Branch of medicine concerned with the formation, composition, effects and    removal of urinary stones.

v   Nocturia: Renal disease in which volume of urine rises so much at night that the person is compelled to wake up to ease out.

v   Nocturnal Enuresis; Bed wetting during sleep.

v   Dysuria: Difficult or painful micturition (urination).

v   Polyuria: Excretion of an excessive amount of urine.

v   Oliguria: Deficient urine excretion.

v   Anuria: Absence of urine formation by the kidneys.

v   Urine with Abnormal Substances:

(i) Proteinuria: Presence of proteins (albumen, globulin) in urine above trace amount.

(ii) Glycosuria ( Glucosuria): Occurrence of glucose in urine.

(iii) Haematuria: Loss of blood in urine.

(iv) Ketonuria: Excretion of ketone bodies in urine.

(v) Pyuria: Passing pus in urine.

Mr. A. KINGSLIN M.Sc, BEd, Phd,(doing)
Post Graduate Teacher in Botany
St. Mary Goretty Hr. Sec School, Manalikarai 
Kanyakumari district





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