Excretory system

This presentation will be helpful for 10 ICSE students

1. Excretory system Jegatheeswari karthik

2. Need for excretory system Carbon-dioxide is produced from carbohydrate, protein and fat metabolism. Ammonia, Urea and Uric acid are produced from metabolism of protein and nitrogenous compounds. T hese waste products are eliminated by the excretory system in our body.

3. Excretion Ex - out Crete - Flow The process of removal of chemical wastes from the body. T he process of removal of harmful and unwanted nitrogenous waste products from the body.

4. Importance of excretory system 1) It removes waste products and toxic materials formed inside the body. 2) It eliminates excess of materials like soluble vitamins and drugs from our body. 3) It maintains the pH of body fluids. Maintains homeostasis in the body.

5. Substances to be eliminated and How it is eliminated? Respiratory products Nitrogenous metabolic waste Excess salts and Vitamins Water Pile pigments

6. Respiratory products Respiration releases carbon dioxide and water. Carbon dioxide is eliminated by Lungs. Extra Water is eliminated in the form of sweat .

7. Nitrogenous wastes (Urea, Uric acid and ammonia) The liver is a complex organ. It performs over 500 different functions. Two of these are the control of amino acid concentration and detoxification. Urea is produced in the liver and is a breakdown product of amino acids. Ammonium ions are formed in the breakdown of amino acids. Some are used in the biosynthesis of nitrogen compounds. Excess ammonium ions are converted to urea.

8. Nitrogenous wastes U rea is highly poisonous. I f it accumulates in the blood to certain level,causes death.  7 to 20 mg/dL Urea is eliminated through kidneys.

9. Nitrogenous wastes Uric acid  is a waste product found in blood. It is created when the body breaks down chemicals called purines. Most  uric acid  dissolves in the blood, passes through the kidneys and leaves the body in urine. Food and drinks high in purines also increase the level of  uric acid. Normal  Uric acid levels  are 2.4-6.0 mg/dL 

10. Nitrogenous wastes Ammonia - The  normal range  is 15 to 45 µ/dL 

11. Extra salts and vitamins Common salts NaCl is excreted through kidneys. Vit. B and C – water soluble vitamins It is also excreted through kidneys.

12. Water Excess water is removed from the body through kidneys. Serves useful purpose. Dissolve harmful substances and carry them.

13. Bile pigments The most important  bile pigment  is bilirubin, which is orange or yellow. Hemoglobin of dead RBC breaks down into bilirubin Liver cells extract this and it will be present in the bile juice. Juice is then poured into duodenum through bile duct. These pigments are modified in small intestine. Some of them is excreted through faeces some through urine.

14. The excretory organs Excretion in Humans is carried out by Kidneys and Accessory excretory organs Skin Lungs Liver

15. Kidney and accessory organs Kidney Eliminate nitrogenous waste _ mostly Urea, creatinine and uric acid in the form of urine Skin – sweat glands present in the skin removes sweat Sweat contains water, sodium chloride and a very small amount of nitrogenous wastes and lactic acid. Sweat is required for cooling Lungs – removes Carbon dioxide Liver – Detoxify ammonia in the form of urea- removed in urine Liver breaks down bad cholesterol, alcohol, nicotine and drugs.

16. Excretory system Organs which are concerned with the formation, storage and elimination of urine constitutes the Excretory system.

17. Excretory system in humans The human urinary system consists of 1. A pair of kidneys 2. A pair of ureters 3. Urinary bladder 4. Urethra

18. Excretory system in humans .

19. A pair of kidneys Dark red, bean shape, 10 cm long, 6 cm wide The right kidney is slightly lower in position due to the presence of the liver. The renal artery supplies oxygenated blood to the kidneys. The renal veins take away deoxygenated blood from the kidneys.

20. A Pair of Ureters A Pair of Ureters a A pair of ureters Ureters are tube-like structures which arise from the notch, i.e. the hilum of each kidney. The ureters connect behind with the urinary bladder. The ureters carry the urine produced to the urinary bladder.

21. Urinary bladder Muscular sac-like structure. It stores urine temporarily.

22. Urethra Short muscular tube which expels urine out of the body. It is long in males and very short in females. The opening is guarded by sphincters which open at the time of urination.

23. Pelvis  enlarged upper end of the ureter

24. Micturition Micturition or urination is the process of expelling urine from the bladder. This act is also known as voiding of the bladder.  The urinary bladder can store around 350-400ml of urine before it expels it out. T he process of  micturition  is governed by both the nervous and muscular systems. Once the urinary bladder reaches its maximum capacity, the stretch receptors in the walls of the bladder send an impulse via the pelvic nerve to the brain via the spinal cord .

25. Internal structure of kidney Cortex Medulla Conical pyramids Papilla Renal columns Uriniferous tubules or nephron or renal tubules or kidney tubules.

26. .

27. Uriniferous Tubule .

28. Nephron It consists of the following parts Bowman’s Capsule Proximal Convoluted Tubule (PCT) Loop of Henle Distal Convoluted Tubule (DCT)

29. Bowman’s Capsule It is a thin-walled, cup-like depression. A knot-like mass of blood capillaries called glomerulus is located in the concave depression of the Bowman’s capsule. The Bowman’s capsule and the glomerulus together are called Malpighian tubule or renal tubule .

30. Malphigian tubule .

31. Afferent and efferent arteriole Afferent – to bring into – It brings blood to kidney Efferent – to carry away

32. (PCT) Proximal Convoluted Tubule (PCT) It is also known as the first convoluted tubule . It is the first part of the convoluted region of the tubule. PCT lies in the cortex.

33. Loop of Henle It is the U-shaped middle part of the tubule. Not convoluted It runs in medulla and reenters cortex

34. Distal convoluted tubule Distal means Farther – away from Bowman’s capsule It is the end part of the kidney tubule. It opens into the collecting duct Collecting duct receives the content of many kidney tubules and pour it as urine in the pelvis Medulla region

35. Interesting facts about nephron Approximately two million nephrons present in both kidneys Total length of tubules – 60 Km- Provide large surface area Blood flow through kidneys- 1 liter per minute

36. Blood Supply to the Kidneys Blood Supply to the Kidneys Blood Supply to the Kidneys Dorsal aorta renal artery afferent arteriole glomerulus efferent arteriole secondary capillary network (vasa recta) renal vein posterior or inferior vena cava

37. Formation of Urine The process of urine formation occurs in three major steps Ultrafiltration Reabsorption Tubular secretion

38. Ultrafiltration Due to the hydrostatic pressure built in the glomerulus, the liquid part of the blood filters out from the glomerulus and passes into the Bowman’s capsule. This filtration under extraordinary force is called ultrafiltration . The filtrate is known as glomerular filtrate . It consists of water, salts, glucose and other plasma solutes. Remaining large substances are carried away by efferent arteriole

39. Reabsorption The glomerular filtrate passes down the tubule; water and other substances such as glucose and sodium required by the body are reabsorbed. This entire process is called selective reabsorption .

40. Tubular secretion Potassium ions and certain substances such as penicillin are passed into the urine through the distal convoluted tubule. The cells of the walls of DCT are involved in bringing back into the renal tubule potassium ions and other substances; hence, this process is known as tubular secretion .

41. Urine The filtrate left after reabsorption and tubular secretion is called urine.

42. Part of the Renal Tubule Activity Glomerulus Ultrafiltration Bowman’s Capsule Receives glomerular filtrate Proximal Convoluted Tubule (PCT) Reabsorbs water, glucose, sodium and chloride ions Loop of Henle Absorption of water and sodium ions Distal Convoluted Tubule (DCT) Reabsorption of chloride ions and water

43. Urine excretion The filtrate left after reabsorption and tubular secretion is called urine . The urine passes from the collecting duct to the pelvis of the kidneys. From there, it is sent to the urinary bladder through the ureters. By relaxing the sphincters present at the opening of the urethra, the urine is expelled from the body. This process is known as micturition or urination .

44. Physical properties of Urine Colour : Yellow. It is due to the presence of pigment U rochrome. Volume: 1 to 1.5 litres . However, the volume can vary depending on the liquid intake of the person. pH: 5 to 8. Slightly acidic. Protein diet- more acidic vegetable diet- Alkaline Odour : Faint smell. If it is stored for longer time smells ammonia-like due to bacterial activity. Specific gravity:1.003 to 1.035 Urine is made of 95% of water and 5% of solid wastes. The percentage of solid wastes slightly vary with the diet