Excretion

• What are the components of blood?

  Red blood cells, white blood cells, plasma, and platelets
• How do white blood cells protect us against pathogens?

  They identify and destroy harmful microorganisms
• How does heart rate change during exercise?

  Heart rate increases to supply more oxygen to muscles
• What are the learning objectives related to excretion and osmoregulation?

  • Understand the origin of carbon dioxide and oxygen
  • Understand how the kidney carries out excretion and osmoregulation
  • Describe the structure of the urinary system
  • Describe the structure of a nephron
  • Apply the terms ultrafiltration and selective reabsorption
  • Describe the role of ADH
• What is the definition of excretion?

  It is the removal of metabolic waste from an organism
• Name two excretory products in plants.

  Oxygen and carbon dioxide
• Name three excretory organs in animals.

  Lungs, kidneys, and skin
• What is metabolism?

  It is all the chemical reactions that occur inside a living organism
• What are two important metabolic reactions?

  Photosynthesis and respiration
• What waste products are produced by photosynthesis and respiration?

  Oxygen and carbon dioxide
• How is carbon dioxide and oxygen lost in plants?

  Both gases are lost via the stomata
• What are the main excretory products in animals?

  • Carbon dioxide
  • Excess water
  • Salts
  • Urea
• What is the role of the kidneys in excretion?

  They remove waste from the body and regulate water levels
• What is deamination?

  It is the process of removing excess protein from the body
• What is the main excretory product formed from excess protein?

  Urea
• What is the structure of the urinary system?

  • Kidneys
  • Ureters
  • Bladder
  • Urethra
• What are nephrons?

  They are the functional units of the kidneys
• How many nephrons are in each kidney?

  Over one million nephrons
• What is ultrafiltration?

  It is the process that occurs in the Bowman’s capsule
• What is glomerular filtrate made up of?

  Urea, water, salts, and glucose
• Why can't red blood cells pass into the Bowman’s capsule?

  Because the Bowman’s capsule has a three-layered filter system
• Where does selective reabsorption occur?

  In the proximal convoluted tubule
• How does glucose get absorbed in the proximal convoluted tubule?

  By active transport
• What role do mitochondria play in the nephron?

  They provide energy for active transport
• How does water move out of the collecting ducts?

  Via osmosis
• How does ADH affect water reabsorption in the collecting ducts?

  It makes the walls more permeable to water
• Describe the role of ADH in regulating water content of the blood.

  • Receptors in the hypothalamus detect low water levels
  • Signals sent to the pituitary gland to release ADH
  • ADH travels to the collecting duct
  • Increases permeability to water
  • More water reabsorbed into the blood
  • Less urine produced when water levels are low
• What happens when water concentration is high in the blood regarding ADH?

  ADH release is inhibited and less water is reabsorbed
• What does urine contain?

  • Water
  • Urea
  • Ions
• How is the water content of the blood controlled?

  By regulating ADH levels and kidney reabsorption
• What is the role of the hypothalamus in water regulation?

  It detects changes in water concentration
• What happens to urine production when water concentration is low?

  More concentrated urine is produced
• What happens to urine production when water concentration is high?

  More dilute urine is produced
• What are the steps to control water levels in the blood?

  1. Drop in water concentration detected by hypothalamus
  2. ADH released from pituitary gland
  3. Collecting ducts reabsorb more water
  4. Concentrated urine produced
  5. Increase in water concentration in blood
  6. ADH release suppressed
  7. Collecting ducts reabsorb less water
  8. Dilute urine produced
• What are the components of blood?

  Red blood cells, white blood cells, plasma, and platelets
• How do white blood cells protect us against pathogens?

  They identify and destroy harmful microorganisms
• How does heart rate change during exercise?

  Heart rate increases to supply more oxygen to muscles
• What are the learning objectives related to excretion and osmoregulation?

  • Understand the origin of carbon dioxide and oxygen
  • Understand how the kidney carries out excretion and osmoregulation
  • Describe the structure of the urinary system
  • Describe the structure of a nephron
  • Apply the terms ultrafiltration and selective reabsorption
  • Describe the role of ADH
• What is the definition of excretion?

  Excretion is the removal of metabolic waste from an organism
• Name two excretory products in plants.

  Oxygen and carbon dioxide