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