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Human Form & Function

Human Form & Function. The urinary system. Urinary system. The major structural components of the urinary system are: Kidneys Urinary bladder Ureters Urethra. Urinary system. Function To rid the body of wastes , especially nitrogenous wastes such as urea.

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Human Form & Function

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  1. Human Form & Function The urinary system

  2. Urinary system The major structural components of the urinary system are: • Kidneys • Urinary bladder • Ureters • Urethra

  3. Urinary system Function • To rid the body of wastes, especially nitrogenous wastes such as urea. • To regulate the balance of fluid, salt& pH. • The blood is filtered as it passes through the kidneys. • Waste substances are removed by the processes of filtration and tubular secretion. • Useful substances are returned to the body by the process of selective re-absorption.

  4. The kidneys • The functional unit of the kidney is the nephron • A nephron consists of a Bowman’s capsule, a renal tubule and the associated blood supply. • It filters waste products out of the blood • Each kidney contains about 1.2 million nephrons 3HBS

  5. The kidney Proximal convoluting tubule Glomerulus Capsule Cortex Distal convoluting tubule Medulla Renal artery Collecting duct Renal vein Loop of Henle Renal pelvis Capillaries Ureter KIDNEY A NEPHRON

  6. The kidneys Renal medulla – loops of Henle Renal artery Renal vein Renal cortex – Bowman’s capsules Ureter – to the bladder 3HBS

  7. The nephron Common collecting duct Bowman’s capsule Renal corpuscle Distal convolute tubule Proximal convolute tubule Loop of Henle

  8. The renal corpuscle • Filtration takes place in the renal corpuscle. • The renal corpuscle consists of the Bowman’s capsule and a mass of blood capillaries – the glomerulus.

  9. The renal corpuscle Afferent arteriole Efferent arteriole Bowman’s capsule Glomerulus Proximal convolute tubule

  10. Filtration • Filtering the blood is a passive process and occurs under high pressure. • The filtrate includes: • Water • Urea • Glucose • Amino acids • Vitamins • Salts (sodium & chlorine)

  11. Microscopic section through a kidney Glomerulus Tubule

  12. Photograph of a glomerulus taken with a scanning electron microscope Capillaries of the glomerulus Wellcome Images – David Gregory & Debbie Marshall

  13. Re-absorption water • Not all substances in the filtrate are waste products • The nephron re-absorbes needed nutrients • These include: • water • glucose, • amino acids • vitamins • salts salts • water • glucose • amino acids • vitamins urine - water - urea - salts

  14. Section through a renal tubule taken with a scanning electron microscope Wellcome Images – David Gregory & Debbie Marshall

  15. The proximal tubule • Microvilli line the proximal convolute tubule and create a brush border • This greatly increases the surface area for re-absorption. Microvilli L Slomianka ANHB - UWA

  16. Re-absorption

  17. Tubular secretion • Wastes are transfered from the blood into the tubules for excretion • This is an active process • H+ • NH4+ (ammonium) • Creatinine • Toxins • Drugs • Neurotransmitters

  18. Tubular secretion Creatinine is a chemical waste molecule that is generated from muscle metabolism.

  19. Filtration – a summary • Blood enters the glomerulus (Bowman’s capsule) under high pressure. • Water and other small molecules are forced out of the blood vessels • This filtrate is collected and passes through several tubules • Some water and useful substances are reabsorbed • The rest passes through to the uretersand is stored in the bladder for excretion 3HBS

  20. Filtration – a summary Filtration Re-absorption + Tubular secretion Excretion Renal cortex Renal medulla

  21. Deamination Definition: The stripping of nitrogen from amino acid & nitrogen bases (RNA) Deamination occurs in theliver • Nitrogen occurs in the amino (NH2) part of an amino acid. • Nitrogen is toxic to the human body and must be removed. The amino group Alanine

  22. Deamination – chemical reaction • Amino acid →ammonia + organic compounds (used for respiration) • Ammonia(very toxic) + CO2→urea (H2NCONH2)

  23. Nitrogen wastes

  24. Urine • Urine is a clear, transparent fluid. It normally has an amber colour. • It is collected in the bladder and eliminated through the urethra. • The average amount of urine voided in 24 hours is about 1,200 cm3.

  25. Composition of urine The composition of urine varies but typically contains: 95% water 5% other • solutes (organic molecules) • urea • creatinine • uric acid • ions • sodium & chloride ions • other metabolic wastes.

  26. Elimination vs. excretion • Elimination is the removal of undigested food and waste from the body. • Excretion is the removal of metabolic waste produced by cells from the body

  27. Kidney Failure Stage 2 HBS: Excretory System Most kidney diseases affect the glomeruli which reduces their ability to filter the blood (proteins and RBCs will be present in urine) Some lifestyle measures to reduce the risk of kidney damage include: Maintain a healthy weight Don’t smoke Drink plenty of water Alcohol only in moderation Kidney failure is when kidneys lose their ability to excrete waste and control the level of fluid in the body.

  28. Dialysis Stage 2 HBS: Excretory System • Dialysis is a method of removing wastes from the blood when kidney failure occurs. There are two types of dialysis • peritoneal dialysis • haemodialysis

  29. Peritoneal dialysis • Peritoneal dialysis occurs inside the body using the peritoneum (a membrane that lines the inside of the abdominal cavity and covers organs such as stomach, liver and intestines) • A fluid containing glucose and other substances at concentrations similar blood (and no wastes) is pumped via catheter into the abdominal cavity. • Because of the concentration gradient wastes diffuse from the blood into the fluid in the abdominal cavity, useful products stay in the blood as there is not concentration gradient.

  30. Peritoneal dialysis Peritoneal dialysis is usually done each day Stage 2 HBS: Excretory System

  31. Haemodialysis Stage 2 HBS: Excretory System Haemodialysis involves passing blood through an artificial kidney or dialysis machine The blood is passed through many tubes made of differentially permeable membrane and immersed in a bath of fluid. The concentration of substances in the fluid bath are similar to those in the blood (fluid has no waste) Due to concentration gradient wastes are passed from the blood into the fluid, useful substances remain in blood (no concentration gradient)

  32. Haemodialysis Haemodialysis is done for 4 to 5 hours per week. Stage 2 HBS: Excretory System

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