kidneys 1 - overview & ADH

• what are the 3 main roles of the kidneys

  • regulate water levels
  • regulate ion levels
  • remove urea
• how is urea made and excreted

  • 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 called ‘deamination’, and takes place in the liver
  • the process of deamination produces urea
  • urea is excreted by the kidneys
• other than the kidneys, how else are ions lost from the body

  sweating
• why is it important to regulate water levels in the body

  too much water could cause our cells to swell or burst, whilst too little water could cause them to shrink
• what do we call the process by which water enters or leaves cells

  osmosis
• with regards to kidneys, what does the term ‘filtration’ (or ‘ultrafiltration‘) mean

  as blood passes through the kidneys, small substances (like glucose, urea, and water) will pass from the blood into the tubule of the nephron

  this process is called filtration, as only small substances are ‘filtered’ through
• with regards to kidneys, what does the term ‘selective reabsorption’ mean

  as the filtrate passes through the tubule of the nephron, useful substances like glucose are reabsorbed into the blood

  this process is called selective reabsorption because we only reabsorb the substances that we want back into our bloodstream
• which substances are not filtered from the blood into the kidney tubules

  large things such as red blood cells, white blood cells, platelets, and large proteins
• which hormone is responsible for regulating water levels in the body

  antidiuretic hormone (ADH)
• which part of the brain monitors the level of water in the body

  hypothalamus
• does ADH increase or decrease the concentration of water in our bloodstream

  ADH will increase the concentration of water in our bloodstream
• what type of feedback does the body use to regulate water levels

  negative feedback
• how does the body respond to high water levels (include all the steps in your answer)

  • the hypothalamus detects the high concentration of water in the bloodstream
  • this causes it to stop sending signals to the pituitary gland, which will cause the pituitary gland to stop releasing as much antidiuretic hormone (ADH)
  • as less ADH travels around the body, the kidneys wont be stimulated to reabsorb water from the tubules into the blood
  • this means that more water stays in the tubules and more urine will be made
  • as a result, the concentration of water in the blood will fall