control of blood glucose Flashcards
What is negative feedback?
= deviation from normal levels, are restored to their original levels
= involves nervous system and hormones
When does blood glucose concentrations increases?
= indigestion of food or drinks, containing carbohydrates- increases
= excercise and not eating- decreass
What detects changes in blood glucose levels?
= the pancreas
What releases the hormones insulin and glucagon?
= endocrine cells in the islets of langerhans
= allows blood glucose concentrations to be returned to normal
What is adrenaline released by?
= adrenal glands, when body anticiptaes danger
= results in more glucose being released from stores of glycogen in the liver
What happens when blood glucose levels increases what are the general steps?
= detected by beta cells in islets of langerhans (pancreas)
= beta cells release insulin
= liver cells becomes more permeable to glucose and enzymes are activated to convert glucose to glycogen
= glucose is removed from the blood and stored as glycogen in cells
What happens when blood glucose levels decreases what are the general steps?
= blood glucose levels decreases
= detected by alpha cells, in islets of langerhans (pancreas)
= alpha cells releases glucagon, adrenal gland releases adrenaline
= second messanger model occurs to acitivate enzymes to hydrolyse glycogen
What is glycogenesis?
= excess glucose is being conveted to glycogen, when blood glucose levels are higher than normal
= occurs mainly in liver
What is glycogenolysis?
= hydrolosis of glycogen back into glucose in the liver
= this occuers when blood glucose levels are lower than normal
=
What is gluconeogenesis?
= process of creating glucose, from non-carbohydrate stores in liver
= this occues of all glycogen, has been hydrolysed into glucose and body still needs glucose
What do beta cells do?
= detect when blood glucose levels are too high, and secrete insulin in response to this
= insulin decreases blood glucose concentrations
How do beta cells work?
= attaches to receptors on surface of target cells, changes teritary structure of channel protiens, more glucose absorbed by facilitated diffusion
= more protein carriers are incorporated into cell membranes so more glucose is absorbed from blood into cells
= ac tivates enzymes converting, glucosr to glycogen, glycogenesis in liver
What do alpha cells do?
= detect when blood glucose is too low, and will secrete glucagonHo
How do alpha cells work?
= attaching to receptors, on the surface of target cells
= when glucagon binds, it causes a protein to be activated, into adelnylate cyclase, to convert ATP inton cylcic AMP,
= CAMP activates an enzyme, protein, kinase, that can hydrolyse glycogen into glucose
= activating enzyme involves cbversion, of glycerol, amino acids into glcose
What is the second messebger model?
= glucagon binds to glucagon receptors on liver, causes a change in protein, enzyme adenyl cylcase, activates, catalyses the reaction of comverting ATP into cAMP,
= this activates protein kinase into inactive to active form, catalyses hydrolysos of glucagon into glucose
