control of blood glucose concentration

Question 1

List the factors that influence blood glucose concentration

Answer 1

Eating food containing carbohydrates → glucose absorbed from intestine to blood
- Exercise → increase rate of respiration of glucose

Question 2

Describe the action of insulin

Answer 2

• Secreted by beta cells in islets of Langerhans in pancreas when blood glucose concentration is too high
• Insulin binds to specific receptors on cell surface membranes of liver / muscle cells (target cells) - Increases permeability of muscle cell membrane to glucose → by increasing number of channel proteins (GLUT4) in cell surface membrane →cells uptake more glucose from blood by facilitated diffusion
• Activation of enzymes in liver / muscle cells that convert glucose to glycogen (glycogenesis) → store glycogen in cytoplasm
• Rate of respiration of glucose also increases
• DECREASES blood glucose concentration

Question 3

Describe the action of glucagon

Answer 3

• Secreted by alpha cells in islets of Langerhans in pancreas when blood glucose concentration is too low
• Binds to specific receptors on cell surface membranes of liver cells (target cells) - Activates enzymes involved in the conversion of glycogen to glucose
  (glycogenolysis)
• Activates enzymes involved in the conversion of glycerol / amino acids to glucose (gluconeogenesis)
• Rate of respiration of glucose also decreases
• INCREASES blood glucose concentration

Question 4

Describe the role of adrenaline

Answer 4

• Secreted by adrenal glands (above kidneys) when blood glucose concentration is low / stressed / exercising
• Binds to specific receptors on cell surface membranes of liver cells (target cells) -Activates enzymes involved in the conversion of glycogen to glucose (glycogenolysis)
• Inhibits glycogenesis
• Activates secretion of glucagon
• INCREASES blood glucose concentration (more glucose for respiration)

Question 5

Describe the secondary messenger model

Answer 5

• Adrenaline and glucagon demonstrate this because they cause glycogenolysis to occur inside cell even though theybind to receptors on the outside of the cell
  1. Adrenaline / glucagon bind to specific complementary receptors on cell membrane
  2. Activate adenylate cyclase
  3. Converts ATP to cyclic AMP(secondary messenger)
  4. cAMP activates protein kinase A (enzyme)
  5. Protein kinase A activates a cascade to break down glycogen to glucose (glycogenolysis)

Question 6

Compare the two types of diabetes

Answer 6

Type 1-
cause=
gene mutation-autoimmun response on b cells of iselts oon langerhans-body cant produce insulin
control:
injection of insulin
dose of insulin matched to glucose intake
diet manipulation:
control carb inatke
avoid sudden rise in glucose
Type 2-
cause=
poor diet/obeisty
glycoprotein recepter to loses responsiveness to insulin
control:
use od drugs which target insulin receptors
mkore flucose uptake
diet manipulation:
reduced sugar intake
more regular exercise
lose weight