Unit3 Excretory System


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Powerpoint about the Human Excretory System

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Unit3 Excretory System

  1. 1. Unit 3.D: The Excretory System
  2. 2. Index 1. The Urinary System in Humans 2. Excretion 3. The anatomy of the kidneys 4. The production of urine 5. Diseases of excretory system
  3. 3. 1. Parts of the Urinary System in Humans  Kidneys  they remove urea and other waste products from the blood and form urine.
  4. 4.  Ureters  they carry urine from the kidney to the bladder
  5. 5.  Bladder  it stores urine before it is released from the body. It has a muscular wall.
  6. 6.  Urethra  It carries urine out of the body. • Men urethra is common to the reproductive system • Women urethra is an independant tube
  7. 7. 2. Excretion Excretion is the elimination of waste products that are produced by the body cells. The cells release the waste substances into the blood. The blood must, therefore, be purified. Metabolic waste products are: • Nitrogen compounds  excess of protein is broken down in the liver and forms urea • Carbon dioxide • Water • Mineral salts EXCRETORY ORGAN WASTE PRODUCTS Lungs Carbon dioxide, water vapour Kidneys Urea, water and salts Skin Water and salts
  8. 8. 4. The anatomy of the kidneys  Blood enters the kidneys through the renal arteries  Each kidney is made up of thousands of small functional units known as nephrons. Each one of these nephrons filters and purify the blood independently. Glomerulus = capsule which contains lots of blood capillaries  Bowman’s capsule surrounds the glomerulus  The tubules and the loop of Henle carry the urine to the ureters Nephron
  9. 9.  Renal cortex  Bowman’s capsules  Renal medulla  loops of Henle and collecting ducts  Renal pelvis  ducts which collect the urine produced by the nephrons.
  10. 10. 4. The production of urine The formation of urine is a very selective process. Urine contains:  water  toxic substances (urea, uric acid, etc.) urea uric acid The composition of sweat is similar to urine. It is produced by filtering the blood that reaches the skin. Activity 4, page 71 ammonia
  11. 11. 1. Filtering: Substances go from the glomerulus to the Bowman’s capsule 2. Reabsorption: Water and useful substances go back from the tubules to the blood 3. Urine (water, urea, uric acid, salts) arrives to the renal pelvis, where reaches the ureters.
  12. 12. 5. Diseases of Excretory System  Kidney stones  crystals of uric acid
  13. 13.  Cystitis inflammation of the bladder caused by a bacterial infection.
  14. 14.  Renal insufficiency kidneys do not filter the blood correctly and waste products are not removed from the blood
  15. 15.  Hemodialysis  filtering of blood in an apparatus to remove waste products. It is performed in cases of kidney failure.
  16. 16.  Kidney transplant Video  Urinary System, the nephron