BLOOD GLUCOSE

• what organ monitors and controls blood glucose conc?

  pancreas
• What influences blood glucose lvls

  • diet
  • exercise
• Explain how insulin lowers the concentration of blood glucose.

  • pancreas stimulates beta cells in islets of langahan to secrete insulin
  • insulin binds to receptors on liver & muscle cells
  • causes more transport proteins to become active
  • inc permeability of membrane so glucose diffuses out of bloodstream and into cells
  • stimulates enzymes to convert glucose to glycogen (glycogenesis)
  • inc rate of respiration and stimulates lipids formation
• what hormone lowers conc of blood glucose?

  insulin
• what hormone inc conc of blood glucose

  glucagon and adrenaline
• what gland secretes adrenaline

  adrenal gland
• explain how glucagon inc blood glucose levels

  • pancreas stimulates alpha cells in islets of llangerhan to secrete glucagon
  • glucagon binds to receptors on liver cells
  • stimulates breakdown of glycogen to glucose (glycogenolysis)
  • decreases rate of respiration
• Explain how the formation of glycogen in liver cells leads to a lowering of blood glucose concentration.

  • formation of glycogen lowers the concentration of glucose in liver cells below that in the blood. 
  • glucose enters cells via facilitated diffusion
• People with undiagnosed diabetes were not receiving treatments, such as insulin injections. Suggest one reason for why death rates for undiagnosed where higher than diagnosed diabetics.

  1. diabetic coma/ hypoglycaemia= blood glucose lvls dropped too low
  2. heart attack= faster atheroma formation
  3. kidney failure= damage to blood vessels
• Describe the role of glucagon in gluconeogenesis.

  Do not include in your answer details on the second messenger model of glucagon action.

  • attaches to receptors
  • stimulates conversion of fatty acids into glucose
• GLUCONEOGENESIS= Conversion of fatty acids to glucagon activated by glucagon

  (inc blood glucose conc)
• Explain how increasing a cell’s sensitivity to insulin will lower the blood glucose concentration.

  more insulin can bind to receptors

  activates enzymes which convert glucose to glycogen
•  Explain how inhibiting adenylate cyclase may help to lower the blood glucose concentration.

  • no ATP is converted to cAMP
  • no cAMP means no protein kinase A can be produced
  • No glycogen converted to glucose
• HOMEOSTASIS


  maintaining constant internal environment
• Describe the role of the hormone glucagon in the control of blood sugar concentration

  • inc blood glucose conc
  • binds to specific receptor on liver cell
  • stimulates enzymes to convert glycogen to glucose
  • decreases rate of respiration
  • glucose diffuses out of cells via facilitated diffusion
• GLYCOGENOLYSIS= Glycogen into glucose
• GLYCOGENESIS= Glucose into glucagon
•  Describe how bacteria can be genetically modified to produce human insulin.

  Use m-RNA + reverse transcriptase to produce gene / (c)-DNA;2. Restriction enzyme to cut open plasmid;3. Add sticky ends (to insulin gene and to plasmid);
• NEG FEEDBACK= mechanisms which act to reverse a change
• positive feedback mechanisms = amplify a detected change, moving conditions away from the normal level. They are used to accelerate a biological pathway
• why is positive feedback not involved in homeostasis


  doesn't keep internal conditions in normal range
• Neonatal diabetes is a disease that affects newly born children. The disease is caused by a change in the amino acid sequence of insulin.

  This change prevents insulin binding to its receptor. Explain why this change prevents insulin binding to its receptor.

  • Changes tertiary structure;
  • No longer complementary to receptor
• DIABETES=condition that results from the inability to control blood glucose levels.
• TYPE 1 DIABETES

  • immune system destroys the beta cells of the islets of Langerhans so that they can no longer produce insulin.
  • Results in sustained hyperglycaemia (high blood glucose) after a meal.
  • Some glucose is excreted in the urine as the kidneys cannot reabsorb all of the glucose.
  • Treated with insulin injections or an insulin pump.
  • Have to carefully control diet- after eating insulin levels stay high
  • caused by genetic predisposition
• TYPE 2 DIABETES

  • Body cells stop responding properly to insulin because their insulin receptors stop working and their cells stop absorbing glucose.
  • OR B cells don't produce enough insulin
  • Treated with a managed diet and regular exercise.
  • linked w/ obesity
• explain why glucose is found in the urine of a person with untreated diabetes.

  • high conc of glucose in blood
  • not all of the glucose can be reabsorbed at PCT
  • As all carrier proteins are in use (saturated)
• desc secondary messenger system

  • adrenaline binds to receptors which activates enzyme adenyl cyclase
  • catalyses conversion of ATP to secondary messenger cAMP
  • cAMP binds to protein kinase A
  • protein kinase A is phosphorylsed
  • stimulates glycogenolysis (glycogen to glucose)