3.6.4.2 control of blood glucose concentration Flashcards
what influences blood glucose concentration
consumption of carbohydrates and rate of respiration
what is glycogenesis
conversion of glucose to glycogen
what is glycogenolysis
conversion of glycogen to glucose
what is gluconeogenesis
conversion of amino acids/ glycerol to glucose
explain the role of the pancreas in regulation of blood glucose levels
the pancreas detects changes in blood glucose levels
the pancreas can act as an endocrine gland by using cell clusters called islets Langerhans.
the cells within the islets of Langerhans secrete hormones into blood vessels
what cells are found in the islets and what is their role
alpha cells secrete glucagon and are used to increase blood glucose levels
beta cells secrete insulin and are used to decrease blood glucose levels
why are insulin and glucagon important
both hormones help regulate blood glucose levels as glucose is needed for cellular respiration and high blood glucose levels can lead to an osmotic imbalance in cells
which three hormones are needed to regulate blood glucose levels
insulin
glucagon
adrenaline
describe the negative feedback loop when there is an increase in blood glucose levels
the increase is detected by beta cells in the pancreas
the beta cells increase secretion of insulin
the insulin makes the liver more permeable to glucose
glucose is converted to glycogen = glycogenesis
describe the negative feedback loop when there is a decrease in blood glucose levels
the decrease is detected by alpha cells in the pancreas
the alpha cells increase secretion of glucagon
the glucagon triggers conversion of glucagon into glucose = glycogenolysis
the glucose is released into the blood
explain the role of insulin in decreasing blood glucose concentration
insulin is secreted by beta cells in the islets of Langerhan when blood glucose levels are too high
insulin binds to specific receptors on the cell surface membrane of target cells e.g. liver/muscles
this causes more channel proteins to join the cell surface membrane, increasing permeability to glucose, so more glucose enters the cells by facilitated diffusion
enzymes involved in glycogenesis are activated
this will lower glucose concentration in cells by creating a concentration gradient
explain the role of glucagon in increasing blood glucose concentration
glucagon is secreted by alpha cells in the islets of Langerhan in the pancreas when blood glucse levels are too low.
glucaogn attaches to specific recpeotr on cell surace membranes of target cells e.g. liver
this activates enzymes involved in glycogenolysis and gluconeogenesis
this establishes a concentration gradient, so more glucose enters the blood by facilitated diffusion
explain the role of adrenaline in increasing blood glucose concentration
adrenaline is secreted by adrenal glands
adrenaline attaches to specific receptors on cell surface membranes of target cells e.g.liver
this activates enzymes involved in glycogenolysis
this establishes a concentration gradient, glucose enters blood by facilitated diffusion
explain the second messenger model of glucagon
glucagon binds to glucagon receptors which change the shape of adenylate cyclase, activated adenylate cyclase converts ATP into cyclic AMP = cAMP, cAMP activates protein kinase which is the enzyme used in glycogenolysis
explain the second messenger model of adrenaline
adrenaline binds to adrenaline receptors, which activate G protein, which allows the conversion of ATP into cAMP which activates protein kinase which is used in glycogenolysis
what is the difference between type I and II diabetes
type I: beta cells don’t produce enough insulin
type II: insulin receptors are faulty, losing sensitivity to insulin
how is type I diabetes controlled
injections of insulin
controlling carbohydrate intake
how is type II diabetes controlled
reduce sugar intake
more regular exercise
loss of weight
