Excretory system

Human Excretory system

1. Excretory System

2. Excretion The process of removal of wastes produced in the cells of the living organisms is called excretion. Excretory Organ Excretory Products (Excreta) Sent out LUNGS CO2 & Water vapour Expired air SKIN Excess water and salt Sweat LARGE INTESTINE Undigested food Solid waste

3. Excretory Organ Excretory Organ Sent out as Kidneys Nitrogenous waste products- Urea, Uric Acid, Creatinine etc.,. Urine

4. EXCRETION IN HUMAN BEING Kidney filters the blood to remove waste and produce urine.

5. Excretory system Kidney Ureter Urinary bladder Urethra

6. Kidney Cortex Medulla Pelvis Kidney- a pair of dark red bean-shaped organ Placed behind the abdomen on each side of vertebral column The Kidneys are made up of millions of nephrons , which are structural and functional units of the kidneys. Average adult kidney measure about 12 cm in Length 6 cm in width 3 cm in thickness Capsule Each Kidney – 1 million nephrons

7. Convex Concave

8. Mechanism of urine formation Urine Urine is the liquid by product secreted by kidneys. Main purpose is to remove waste like urea, uric acid and excess water from the bood . It occur in kidney Basic filtration unit: Nephrons Adult human being normally passes about 1-1.8L of urine in 24 hours- 95% water, 2.5 Urea, 2.5 % other waste products.

9. Structure of Nephron Medulla Cortex

10. Urine formation steps Glomerular Filtration Reabsorption Secretion

11. Filtration Filtration of blood takes place in glomerulus . Termed as Glomerulus filtration . Blood reaches glomerulus by Afferent Arteriole. Increased pressure of blood in glomerulus causes 3- layer filtration of blood.

12. 3- layer filtration of blood Blood is filtered through 3 layers: Endothelium of glomerular blood vessels Epithelium of Bowman’s capsule( podocytes ) Basement membrane Slit pore Fine filtration of blood through the 3 layered membranes is termed as Ultra filtration . Filtered plasma----Bowman’s capsule---- PCT Conc. Blood cells----- Efferent arteriole--- Capillary

13. Glomerular Filtration Rate Amount of glomerular filtrate produced per day- 160 liters. Amount of filtrate(1100-1200ml) formed by the kidneys per minute is called G lomerular F iltration R ate.

14. Reabsorption Almost 99% of the filtrate is reabsorbed by renal tubules Useful substances are reabsorbed by epithelial cells of tubules & sent back to blood Glucose Na+ Active transport Amino Acids H2O ------(Passive transport)

15. Role of the different tubules in Reabsorption & Secretion REABSORPTION SECRETION Proximal Convoluted Tubule(PCT) Large amount of reabsorption occur here Henle’s loop Min. reabsorption occur here Distal Convoluted Tubule(DCT) Conditional reabsorption occur here Na+,H2O, HCO3- etc. Collecting duct Large amount of reabsorption of water occur here Proximal Convoluted Tubule(PCT) Selective secretion of H+,NH3,K+ Distal Convoluted Tubule(DCT) Selective secretion of H+,NH3,K+ Collecting duct Selective secretion of H+,K+

16. Functions of kidney It excretes nitrogenous waste (urea) formed as a result of protein metabolism. It helps to maintain the fluid and electrolyte balance of our body. It helps to retain important plasma constitute like glucose and amino acids.

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