NEET GURU Chap 19 Excretory product and their Elimination PDF

# Excretory Products & Their Elimination ## Toxicity - Ammonia > Urea > Uric acid ## Ammonotelic - Fishes, aquatic insects, amphibians ### No role of kidney in excretion. ## Ureotelic - Terestial amphibians, marine fishes ## Uricotelic - Reptiles, birds, land snails & insects ## Medullary pyra...

# Excretory Products & Their Elimination ## Toxicity - Ammonia > Urea > Uric acid ## Ammonotelic - Fishes, aquatic insects, amphibians ### No role of kidney in excretion. ## Ureotelic - Terestial amphibians, marine fishes ## Uricotelic - Reptiles, birds, land snails & insects ## Medullary pyramid - Column of Bertini - Cortex ## Kidney - Bean-shaped - **Location:** Last thoracic & third lumbar vertebrae - **Length:** 10-12 cm - **Width:** 5-7 cm - **Thickness:** 2-3 cm - **Unit:** Nephron - **Each Kidney:** 1 million nephron ## Protonephridia/Flame cells - Platyhelminths - Rotifers - Some Annelids - Cephalochordate - Amphioxus - eg. Earthworm ## Nephridia - Annelids ## Malphigian tubules - Insect - eg. Prawn ## Antennal/Green gland - Crustaceans ### Calyx - Renal artery - Renal vein - Ureter - Renal Pelvis - → Efferent arteriole - Afferent arteriole - Glomerulus - Bowman's capsule - PCT - DCT - Collecting duct - → Vasa recta ## Malphigian body or renal corpuscles - Glomerulus & Bowman's capsule - Henle's loop - Hairpin shaped - PCT, DCT & Malphigian body → Cortex region - Loop of Henle → Medulla - Cell's of Bowman's capsule - Podocyte --- # Urine Formation ## Glomerular filtration - Reabsorption - Secretion - Ultra-filtration of blood (1100-1200 ml/min) - Glomerular Filtration Rate (GFR) (125 ml/min or 180 l/day) - → Filterate formed per minute. ## GFR regulated by - JGA (Juxta-Glomerular Apparatus) - Formed where DCT & Afferent arteriole contact - If GFR ↓ JG cells secrete Renin - Increase GFR by increasing blood flow. ## Urine released - 1-5 l/day ## Reabsorption - Passively water & nitrogen waste - Actively → Glucose, Amino Acid & Na+ ## PCT (Proximal Convoluted Tubule) - Absorb → Most of nutrients (70-80% electrolytes, water, HCO3-) - Secrete → H+, NH3, K+ ## Descending loop - Permeable to water - Concentrates filterate - Imperm. to elytes ## Henle's loop - Ascending loop - Imperm. to water - Permeable to elytes - Dilutes filterate ## DCT - (Distal Convoluted tubule) - Absorb → Na+, HCO3, & water - Secrete → H+, K+ & NH3 ## Collecting duct - Some urea from this duct pass to medullary interstitium to keep osmolarity. ## Counter-Current Mechanism - Created as - flow of filtrate in two limbs of H-L and in vasa recta is in opposite direction. - Helps in urine concentration. - Urine 4 times more concentrated than initial filterate. ## Osmolarity - Cortex: 300 mosmol/l - Medulla: 1200 mosmol/l - Gradient is due to NaCl + urea ## Urinary bladder - Stretches when it fills up with urine - Gives signal to CNS ## Urine is released i-e - CNS gives signal to initiate contraction of smooth muscles af bladder - Relaxation of urethral sphincter ## Micturition --- # Regulation ## Hypothalamus - If GFR decreases - Posterior pituitary - ADH/Vasopressin - Water reabsorption mainly from DCT - Blood pressure ↑ - GFR increases ## Heart - If blood flow in Atria increases - Atrial-Natriuretic Factor (ANF) - Vasodilation - Blood pressure decrease - GFR decreases ## JGA - If GFR ↓ - Activate JG cells - Release Renin ## Renin - Angiotensin Mechanism - Renin converts Angiotensinogen to Angiotensin I and then to Angiotensin II - Powerful vasoconstrictor - Blood pressure ↑ - GFR ↑ ## pH of urine - 6.0 ## 25-30 gm urea excreted/day ### Glycoswria - Glucose in urine - Indicates Diabetes Mellitus ### Ketonuria - Ketone bodies in urine - Indicate Diabetes Mellitus ## Lungs - 200 ml CO2/ minute ## Liver - Bile salts - Degraded steroid hormone - Cholesterol - Vitamins & drugs ## Sweat - Sebaceous gland - NaCl - Urea - Lactic acid - Sterols - Hydrocarbons - Waxes ## Hemodialysis - Cleared blood is added with anti-heparin - Pumped to veins. - Blood in artery - Added anticoagulant like heparin - Pumped to Dialysing unit - Cellophane + Dialysing fluid - Plasma without nitrogen waste. ## Disorders ### Uremia - Urea accumulation in blood - May lead to kidney failure ### Renal calculi - Stone of crystalised salt (eg. Oxalates) ### Glomerulonephritis - Inflammation of glomeruli of nephron ## Ultimate remedy to kidney failure - Kidney transplant.