control of blood glucose conc

• what happens when blood glucose levels increases

  • beta cells in islets of langerhans detect the change and release insulin
  • causes liver cells to become more permeable to glucose and activates enzymes to convert excess glucose → glycogen for storage
• what happens when blood glucose levels decreases

  • alpha cells in islets of langerhans detect the change and release glucagon
  • 2nd messenger model - activates enzymes to hydrolyse glycogen 
  • glycogen → glucose and released into the blood
• glycogenosis:

  excess glucose converted to glycogen
• glycogenolysis:

  hydrolysis of glycogen → glucose
• gluconeogenesis:

  creating glucose from non-carbohydrate stores (amino acids/glycerol)
• action of insulin:

  • attaches receptors to target cells - changes the tertiary structure of proteins so more glucose are able to be absorbed
  • increase in no. protein carriers in the cell membrane - increases the uptake of glucose
  • activates enzymes needed to convert glucose → glycogen (glycogenosis)
• action of glucagon:

  • attaches receptors to target cells for protein - adenylate cyclase becomes activated
  • adenylate cyclase converts ATP to cyclic AMP 
  • cAMP can activate protein kinase to hydrolyse glycogen → glucose (glycogenolysis)
  • also activates enzyme for converting glycerol/amino acids → glucose
• role of adrenaline:

  if blood glucose is too low:

  • adrenaline increases blood glucose
  • attaches to receptors on surfaces of target fells 
  • causes proteins to be activated: converting ATP → cAMP
  • cAMP activates an enzyme: hydrolyses glycogen → glucose
• type I diabetes:

  body is unable to produce much insulin

  • mainly occurred in childhood
  • treatment: injections of insulin
• type II diabetes:

  receptors on target cells lose responsiveness to insulin

  • due to obesity/poor diet
• osmoregulation:

  control of water potential in the body

  • occurs in the nephrons - found in the kidney
• Explain how insulin lowers the concentration of blood glucose.

  • beta cells in islets of langerhans detect the change and release insulin
  • Binds to receptor on target/liver/muscle cell;
  • Glucose (diffuses) into cells (and lowers blood glucose)
  • (Enzymes in cells) convert glucose to glycogen;