Excretion

• What is the purpose of the kidney linked to?

  MRS C GREN
• What is excretion?

  Removal of metabolic waste products
• What is urea?

  A metabolic waste product
• How does urea exit the nephron?

  Through the ureter into the bladder
• What does control of internal conditions mean?

  Maintaining constant levels within a narrow range
• What does the kidney adjust in the blood?

  Water and salt ion levels
• What is ultrafiltration?

  Process of filtering blood in the kidney
• How does blood enter the glomerulus?

  Under high pressure
• What small molecules are forced into the Bowman’s capsule?

  Water, glucose, ions, and urea
• What cannot pass through the basement membrane?

  Larger molecules like proteins
• What is selective reabsorption?

  Reabsorption of specific substances back into blood
• How is glucose reabsorbed in the proximal convoluted tubule?

  By active transport
• What happens to water in the collecting duct?

  It is reabsorbed by osmosis
• What occurs when a person is overhydrated?

  Blood becomes too dilute with water
• How does the hypothalamus respond to dilute blood?

  Releases less ADH
• What effect does less ADH have on the collecting duct?

  It becomes less permeable to water
• What happens to urine when less water is reabsorbed?

  More water is passed out in urine
• What happens when a person is dehydrated?

  Blood becomes too concentrated
• How does the hypothalamus respond to concentrated blood?

  Releases more ADH
• What effect does more ADH have on the collecting duct?

  It becomes more permeable to water
• What happens to urine when more water is reabsorbed?

  Less water is passed out in urine
• What are the ways water is taken into and lost from the body?

  • Taken in as food and drink
  • Lost by sweating
  • Lost by breathing
  • Lost as urine