regulation of blood glucose concentration

Question 1

what happens when blood glucose concentration increases

Answer 1

• increase detected
• beta cells stimulated in islets of langerhands - pancreas
• insulin released into blood
• insulin binds to insulin receptor proteins
• causes change in tertiary structure
• vesicles containing glucose carrier proteins formed and move to membrane (exocytosis)
• vesicles fuse with membrane
• glucose carrier proteins added to membrane
• glucose transported into cell - facilitated diffusion

Question 2

what happens when blood glucose concentration increases - within the cell

Answer 2

• enzyme glycogen synthase - activated by phosphorylation
• glycogen synthesised = glycogenesis

Question 3

what happens when blood glucose concentration increases - right conc reached

Answer 3

• insulin no longer binds to the receptor
• cell membrane loses its glucose carrier proteins (endocytosis)
• enzyme now inactive
• beta cells stop secreting insulin

Question 4

what happens when blood glucose concentration decreases

Answer 4

• decrease detected
• alpha cells secrete glucagon
• glucagon binds to glucagon receptor proteins
• change of specific tertiary structure
• activates enzyme adenylate cyclase

Question 5

what happens when blood glucose concentration decreases - inside cell

Answer 5

• adenylate cyclase coverts ATP to cyclic AMP
• cAMP acts as secondary messenger within cell
• kinase enzymes activate other enzymes
• activates enzymes to hydrolyse glycogen into glucose - glycogenolysis
• activates enzymes to synthesise glucose from non-carb sources - gluconeogenesis
• more glucose transport proteins fuse with membrane to allow glucose to leave

Question 6

what happens when blood glucose concentration decreases - right conc reached

Answer 6

• glucagon no longer binds to the receptor
• membrane loses glucose carrier proteins
• enzyme now inactive
• alpha cells stop secreting glucagon