Excretion

• What is excretion?

  Excretion is the removal of waste products of metabolism, toxic materials, and substances in excess of their requirements.
• What are waste products of metabolism called?

  Waste products of metabolism are called excretory products.
• What is metabolism?


  Metabolism is the chemical reactions that occur within a living organism.
• What is an example of a metabolic reaction?

  An example of a metabolic reaction is respiration.
• What do metabolic reactions produce?

  Metabolic reactions produce substances that the cell needs.
• What happens if waste products remain in the cell?

  If waste products remain in the cell, they may become toxic.
• What is the difference between egestion and excretion?

  Egestion is the removal of undigested food, while excretion is the removal of metabolic waste products.
• What are the excretory products in mammals?

  • Carbon dioxide
  • Urea
  • Excess water and salts
  • Bile pigments
• What are nitrogenous wastes?

  Nitrogenous wastes are excretory products containing nitrogen.
• How are nitrogenous wastes formed?

  Nitrogenous wastes are formed from the breakdown of excess proteins and amino acids.
• What are examples of nitrogenous wastes?


  Examples of nitrogenous wastes include urea, ammonia, and uric acid.
• What is deamination?


  Deamination is the removal of the nitrogen-containing part of amino acids to form urea.
• What is osmoregulation?


  Osmoregulation is the control of the amount of water in the blood.
• What happens if the amount of water in the blood falls too low?

  The body will trigger mechanisms to conserve water and restore balance.
• What happens if the amount of water in the blood is too high?

  The body will trigger mechanisms to excrete excess water and restore balance.
• Where are osmoreceptors located?

  Osmoreceptors are located in the hypothalamus.
• How does osmoregulation occur in the kidneys?

  Osmoregulation occurs by controlling the amount of water reabsorbed in the kidney collecting ducts.
• What hormone is secreted when the amount of water in the blood is too low?

  Antidiuretic hormone (ADH) is secreted when the amount of water in the blood is too low.
• What triggers the release of ADH?

  ADH is released when the body is dehydrated.
• What is the function of antidiuretic hormone (ADH)?

  ADH acts when the body’s water is low, decreasing urine production and increasing blood pressure.
• What happens to ADH levels when a person is overhydrated?

  When a person is overhydrated, ADH is inhibited.
• How does ADH affect the collecting ducts in the kidneys?

  ADH increases the permeability of the collecting duct to water by increasing the production of aquaporins.
• What is the result of increased ADH activity in terms of urine concentration?

  Less water remains in the filtrate, making urine concentrated and resulting in less urination (anti-diuresis).