A. Blood glucose control

• What is homeostasis

  Maintains a constant internal environment. Despite changes in external environment
• What is blood ph regulated between

  7.35-7.45
• What happens if blood ph becomes too high or too low

  Enzymes may become denatured as tertiary structure changes.
• What is core temperature

  37 degrees
• What happens if body temp is too low

  enzyme activity reduced so slows metabolic rate. Cells can’t respire fast enough.
• What happens if core temp is too high

  Enzymes denature
• What is hyperglycaemia

  High blood glucose levels
• What is hypoglycaemia

  Low blood glucose levels
• Why is high blood glucose levels dangerous

  Water potential of blood will decrease meaning water enters the blood. Organs can become dehydrated
• Why is low blood glucose levels dangerous

  Cells won’t have enough glucose to respire. Water potential of blood increases so water enters cells causing them to swell.
• What is a negative feedback loop

  A change from a set point is detected. Brings about physiological mechanisms to return to set point.
• What is a positive feed back loop

  Not a homeostasis mechanism as it enhances the original change.
• What do hormones affect

  Target cells
• What is normal blood glucose level

  5 mmol dm-3
• Where are the islets of langerhans

  Pancreas
• What do the islets of langerhans do

  Detect changes in blood glucose concentration
• What happens if blood glucose levels increase 


  Receptors on b cells in the islets of langerhans detect the change. Secrete insulin into the blood stream. Insulin binds to specific receptors in target cells
• How does insulin lower blood glucose levels

  Increases number of channel proteins in the membrane so more glucose can enter the cell
• What is glycogenesis

  When insulin activates enzymes that convert glucose to glycogen in the liver and muscle cells. increases respiration rates in cells
• What happens if blood glucose levels decrease

  Receptors on alpha cells in the islets of langerhans detect the change. Release glucagon and it binds to specific receptors in target cells
• How does glucagon increase blood glucose levels

  Glycogenolysis and gluconeogenesis
• What is glycogenesis

  Glucagon activates enzymes that catalyse the conversion of glycogen to glucose
• What is gluconeogenesis

  Glucagon activates enzymes that stimulate the conversion of amino acids and glycerol to glucose
• What are hormones produced by

  Endocrine glands
• What makes a protein receptor specific

  Each has a specific tertiary structure
• Where is adrenaline secreted from

  Adrenal glands
• When is adrenaline secreted 


  When blood glucose is low
• What does adrenaline bind to

  Receptors on liver cell membranes
• When adrenaline binds to the liver cells what happens

  Inactive adenylate Cyclase becomes activated.
• What activates adenylate cyclase 


  When adrenaline binds to liver cells
• What does activated adenylate cyclase do

  Causes ATP to become cyclic AMP
• What causes ATP to become cyclic AMP

  Adenylate cyclase
• What does cyclic AMP act as

  2nd messenger
• What does cyclic AMP do

  Activates protein kinase
• When activated what is protein kinase known as

  Protein kinase A
• What does protein kinase A do

  Converts glycogen into glucose
• What is diabetes

  A disease where the body is no longer able to control blood glucose levels
• What is type one diabetes

  B cells don’t produce insulin and appears in childhood
• What are effects of type one diabetes

  Hyperglycaemia- too much glucose
• What is treatment for type one diabetes

  Biosensor - insulin injections