control of blood glucose concentration Flashcards
which organ monitors blood glucose concentration?
the pancreas
list examples of factors which affect blood glucose concentration
- blood glucose concentration increases after eating food containing carbohydrates
- blood glucose concentration decreases after exercise as glucose is a respiratory substrate used up in respiration to release energy (ATP)
which hormones in the hormonal system control blood glucose concentration
- insulin
- glucagon
explain where insulin is secreted in the body
- in the pancreas
- in the islets of Langherhans
- by Beta cells
- into the blood
explain where glucagon is secreted in the body
- in the pancreas
- in the islets of Langherhans
- by alpha cells
- into the blood
what is the function of insulin
insulin lowers blood glucose concentration when its too high by acting on effectors
outline the action of insulin
- insulin attaches/binds to receptors on surfaces of target cells (cell membranes of liver cells and muscle cells)
- increasing the membrane permeability of target cells to glucose by increasing the number of channel proteins in the cell membranes, so more glucose diffuses into cell
- insulin activates enzymes in the liver and muscle cells that convert glucose into glycogen via glycogenesis
- insulin increases the rate of respiration of glucose in muscle cells
what is the function of glucagon
glucagon increases blood glucose concentration when its too low by acting on effectors
outline the action of glucagon
- glucagon attaches/binds to receptors on the cell membranes of target cells (liver cells)
- glucagon activates enzymes in the liver cells that break down glycogen into glucose via glycogenolysis
- glucagon activates enzymes involves in the formation of glucose from glucerol and amino acids via gluconeogenesis
- glucagon decreases the rate of respiration of glucose in cells
explain why hormonal response is slower than the nervous response but lasts longer
- hormones travel in the blood to their target cells so they are slower
- hormones are not broken down as quickly as neurotransmitters so their effects last longer
explain the role of the liver in glycogenesis
converts glucose into glycogen by secreting insulin
explain the role of the liver in glycogenolysis
converts glycogen into glucose by secreting glucagon
explain the role of the liver in gluconeogenesis
converts non-carbohydrates (like glycerol and amino acids) into glucose by secreting glucagon
name an example of a glucose transporter
GLUT4
outline how glucose moves through a glucose transporter
- when insulin levels are low, GLUT4 is stored in vesicles of cytoplasm cells
- when insulin binds to receptors on the cell surface membrane, it triggers the movement of GLUT4 to the membrane
- glucose is transported into the cell through the GLUT4 protein via facilitated diffusion
outline the role of adrenaline
- adrenaline binds to receptors in the cell membrane of (target cells) liver cells
- it activates enzymes involved in glucogenolysis (breakdown of glycogen into glucose)
- it inhibits enzymes involved in glycogenesis (synthesis of glycogen from glucose)
- activates glucagon secretion and inhibits insulin secretion to increase glucose concentration
where is adrenaline secreted
secreted from adrenal glands
where is adrenaline secreted
secreted from adrenal glands
what is the function of adrenaline
increases blood glucose concentration
explain how adrenaline prepares the body for action
- glucose is a respiratory substrate
- by making more glucose available for muscles to respire
what hormones act as secondary messengers
- adrenaline
- glucagon
what makes adrenaline and glucagon secondary messengers
they can activate glycogenolysis inside a cell by binding to receptors on the outside of the cell
outline the second messenger model
- the receptors for adrenaline and glucagon have specific tertiary structures, making the complementary in shape to their respective hormones
- adrenaline/glucagon bind to their receptors and activate the enzyme adenylate cyclase
- activated adelyate cyclase converts ATP into cyclic AMP (cAMP)
- CAMP activates an enzyme called protein kinase A
- protein kinase A activates glycogenolysis
when do diabetes occur
when blood glucose concentration is not controlled
what is the cause of diabetes type I
- the immune system attacks the beta cells in the islets of Langerhans
- so they can’t produce any insulin
what are the treatments for type I diabetes
- insulin therapy = regular insulin injections throughout the day or an insulin pump
- eating regularly and controlling simple carbohydrate intake to avoid a sudden rise in glucose
what is the cause of diabetes type II
- beta cells don’t produce enough insulin
- or body cells do not respond to insulin due to malfunction in receptors on their membranes so not enough glucose is taken up
what are the treatments for type II diabetes
- eating a healthy, balanced diet, losing weight and regular exercise
- glucose-lowering medication
- insulin injections
evaluate the treatments type II diabetes
- NHS’s campaigns like Change4Life aim to educate people on having a healthier diet and lifestyle so reduce risk of development of conditions like diabetes II
- health advisors challange the food industry to reduce the advertising of fast food, to improve the nutritional value of their products and to use clearer labelling on products so consumers can make healthier choices
- food companies have attempted to make their products more healthy by using sugar alternatives or reducing the sugar, fat and salt content of the food but there is pressure on companies to increase profits
how do you measure the concentration of a glucose solution
- Add Benedict’s reagent and heat with glucose, initial blue colour is lost but a brick-red precipitate is not produced
- use colorimeter to measure light absorbance of solution
- the higher the concentration the more blue colour will be lost, decreasing the absorbance of the solution
