Kidneys 1 - Overview & ADH

• What are the functions of the kidneys?

  • Regulate ion levels 
  • Regulate water levels 
  • Remove urea
• Deamination 

  • If the body has more amino acids than it needs, it can convert them into lipids or carbohydrates, which can be stored as an energy source for later.
  • This process is known as deamination, and takes place in the liver
  • The downside of this process is that it produces the waste product urea, which has to be excreted by the kidney. 
• Select two ways ions be removed from the body? 

  • By sweating 
  • By the kidneys 
• True or false? Ions have many uses in the body, but if their concentration in the blood get too high, or too low, it can damage cells and make us ill. 
• If we have too much water in the body, what could happen to our cells?

  They could gain water and burst

  • If the body has more water than it needs, the water could enter our cells by osmosis, causing them to swell, and possibly even burst.
• Cells can gain or lose water by osmosis
• Each kidney contains millions of tiny units called nephrons.
• tubule

  
• Capillary 

  
• As blood passes through the kidneys, small substances like glucose, amino acids, and water, are absorbed from the blood into the kidneys.

  What do we call this process? 

  Filtration (or ultrafiltration)
• As the filtrate passes through the kidneys, useful substances like glucose are reabsorbed from the tubules, into the blood.

  What do we call this process? 

  Selective reabsorption 
• Which substances are not filtered from the blood into the kidney tubules? 

  • Red blood cells 
  • Large proteins 

  Only small substances can pass from the glomerulus into the Bowman's capsule. Red blood cells and large proteins are both too large to pass across. 
• Which hormone is responsible for regulating water levels in the body? 


  Antidiuretic hormone (ADH)
• Which part of the brain detects the level of water in the body? 


  Hypothalamus 
• How the body responds to low water levels

  • A part of the brain called the hypothalamus detects the low concentration of water in the bloodstream.
  • This causes it to send a signal to the pituitary gland, which tells it to release more antidiuretic hormone (ADH).
  • The ADH travels around the body in the blood, and stimulates the kidneys to reabsorb more water from the tubules into the blood. 
  • This means that less urine will be made, and the concentration of water in the blood rises. 
• Does ADH increase or decrease the concentration of water in our bloodstream? 

  Increase 
• What type of feedback does the body use to regulate water levels?

  Negative feedback