The Kidneys

• What should you be able to describe by the end of the video on water loss in the human body?


  The different ways that water can leave the human body
• What is the role of the kidney in the human body?


  To maintain the concentration of substances in the blood
• What should higher tier students be able to explain regarding amino acids?


  How the body deals with excess amino acids
• What process was previously studied that involves the movement of water?

  Osmosis
• How is osmosis defined?


  As the diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane
• Why is it important for the body to maintain constant water levels in the blood?

  To ensure cells work efficiently
• What happens if the blood becomes too dilute?

  Water moves into cells by osmosis
• What occurs if the blood becomes too concentrated?

  Water moves out of cells by osmosis
• What is homeostasis in relation to water balance?


  A system the body uses to maintain its water balance
• Through what means does the body take in water?


  Through food and drink
• What are the three ways the body can lose water?

  • Via the lungs when exhaling
  • Through sweating
  • Via the kidneys in urine
• How does the body lose water through the lungs?


  By exhaling, and this loss cannot be controlled
• What substances are lost when sweating?

  Water, ions (like sodium), and urea
• Why can't the body control water loss through sweating?

  Because sweating is part of the body's temperature control system
• How do the kidneys contribute to water loss?


  By controlling how much water is lost in urine
• What happens to excess water in the kidneys?


  It is removed and produces a greater volume of urine
• What waste products do the kidneys remove?

  Urea, excess ions, and excess water
• What is the pathway of blood through the kidneys?


  Blood enters through an artery and leaves through a vein
• What happens to the concentration of urea in the blood after passing through the kidneys?


  It falls to virtually zero
• What is selectively absorbed in the kidneys?


  Glucose, some ions, and some water
• How do the kidneys adjust the levels of ions in the blood?


  By filtering out ions and reabsorbing a certain amount back into the blood
• What is the process called when the liver breaks down excess amino acids?

  Deamination
• What toxic chemical is produced from the breakdown of excess amino acids?

  Ammonia
• How does the liver handle ammonia?

  It converts ammonia to urea
• What happens to urea after it is produced in the liver?


  It is safely excreted by the kidneys