Excretory Products and Their Elimination - PDF
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Ramnarain Ruia Autonomous College
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This document provides a short note on excretory products and their elimination. It discusses common nitrogenous wastes, different excretory structures, and the human excretory system. It's good resource for students studying biology and related subjects.
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CHAPTER Excretory Products and their 7 Elimination EXCRETORY WASTE...
CHAPTER Excretory Products and their 7 Elimination EXCRETORY WASTE Metabolism Excess ingestion Results in accumulation of Nitrogenous wastes– NH2, urea, uric acid Other contents – CO2, H2O, ions (Na+, K+, Cl , PO4 , SO4 ) – 3– 2– Removed Partially/Completely Common Nitrogenous Wastes Nature of nitrogenous waste formed and their excretion vary among animals depending on the habitat/availability of water. Toxicity level and water Common nitrogenous waste Nature & Examples Special Features required Ammonia Ammonotelic Maximum Diffusion through gills surface or (Ammonia converts into urea in Aquatic insects body surface as ammoium NH4+ ions liver) Many bony fishes Aquatic amphibians Urea Ureotelic Lesser Kidneys filter urea from blood Marine fishes Many terrestrial amphibians Mammals Uric acid Uricotelic Least Pellet/Paste (Semi-solid) Land snails Minimum loss of water Insects Reptiles Birds Kidneys do not play a significant role in removal of ammonia. Different Excretory Structures Excretory strcuture eliminate nitrogenous waste & maintain Antennal/Green glands Crustaceans (Prawn) fluid and ionic balance Function of excretory structures: Structures Examples Eliminate nitrogenous wastes. P rotonephridia/flame Platyhelminthes (Planaria) Maintain ionic and acid-base balance of body fluids, i.e., cells (osmoregulation) Rotifers osmoregulation. Some annelids Cephalochordates (Amphioxus) Nephridia Annelids (Earthworms) Malpighian tubules Insects (Cockroaches) HUMAN EXCRETORY SYSTEM Inferior Adrenal gland vena cava Renal artery 1 pair, bean shaped, Pelvis Renal vein reddish brown Medulla Kidney Length 10-12 cm, Width 5-7 cm, Cortex Thickness 2-3 cm Dorsal aorta Weight 120-170 g Ureter [1 pair] Between T12 - L3 vertebra, close to dorsal inner wall Urinary of abdominal cavity bladder Have stretch receptors Urethra Guarded by sphincters MICTURITION Process of release of urine CNS (voluntary signals) Mechanism -Micturition reflex Send motor messages Urimary bladder Urinary bladder (Store urine) Smooth muscles of Bladder Activates contractUrethral sphincters relax signals Release Stretch receptors Urine Distal convoluted tubule Collecting duct Juxtaglomerular apparatus (JGA): Cellular modifications in DCT and afferent arteriole at the location of their contact. JGA is composed of JG Cells and Macula densa. DCT and collecting duct concentrate the filtrate about four times. P W Excretory Products and their Elimination 17 Filtration is due to pressure in the glomerular capillaries. Glomerular filtration rate (GFR) = Filtration/min 125 ml/min Operates between the two limbs of loop of Henle and vasa recta VR HL 300 mOsm/L Cortex 600 mOsm/L H2O NaCl H2O H2O Urea Urea 900 mOsm/L Medulla NaCl H2O 1200 mOsm/L The Filtrate gets concentrated as it moves down the descending loop of Hence and diluted as it move by ascending loop of Henle. REGULATION OF KIDNEY FUNCTION Hypothalamus JGA/ Renin-Angiotensin Mechanism Heart Works when GFR Low, Blood Volume Low GFR/ Glomerular blood Increase blood flow to atria of heart Low flow/Glomerular blood pressure ↓ osmoreceptors in hypothalamus Activate↓ Release of ANF (Atrial natriuretic factor) activated. JG cells to release renin ↓Work Release of ADH/ Vasopressin Vasodilation ↓ Angiotensinogen Angiotensin I (Liver) ACE - ↓Result Prevent Diuresis Angiotensionogen Angiotensin II converting enzyme Blood pressure decrease Activate (Vasopressin) GFR decrease Checks on Renin-Angiotensin Adrenal cortex aldosterone Mechanism ↓ Reabsorption of Na+ & water from distal part of Tubule ↓ Blood pressure and GRP increase 18 NEET (XI) Module-2 Zoology PW Characteristics and Composition of Urine Disorders of Excretory System Colour - Light yellow Disorders Symptoms or Treatment pH = 6 Renal calculi Stone or insoluble mass of crystalised salts Odour - Characteristic (e.g., oxalates) Urea - 25-30 gm/day Glomerulonephritis Inflammation of glomeruli of kidney Glucosuria [Glucose in urine] Renal/kidney Malfunctioning of kidneys may lead to Diabetes mellitus failure kidney failure. Ketonuria [Ketone in urine] Treatment Role of Other Organs in Excretion (i) Haemodialysis: Process to remove urea from blood Accessory structure Basic work Boon for thousands of uremic patients Lungs Remove large amount of CO2 all over the world. Approximately 200 mL/min Composition of dialysing fluid is same Remove significant quantity of water as plasma except the nitrogenous wastes. Liver (Largest gland) Remove Bile-containing substances (ii) Kidney transplantation along with Digestive wastes. Ultimate method in correction of acute Skin Removes NaCl, urea and lactic acid renal failure Sweat gland Facilitates cooling effect Functional kidney is taken from donor Sebaceous gland Removes steroles, hydrocarbons, To minimise rejection, close relatives waxes. are preferred as donor Salivary glands Small amount of nitrogenous wastes Modern clinical problems have increased are eliminated through saliva success rate of such complicated techniques P W Excretory Products and their Elimination 19
