14.3 Regulation of blood glucose concentration Flashcards
What are the processes of decreasing glucose conc
RESPIRATION - uses glucose as reactant to form ATP
GLYCOGENESIS - formation of glycogen from excess glucose
What are the processes of increasing glucose conc
GLYCOGENOLYSIS - hydrolysis of glycogen in liver & muscle cells to release glucose into bloodstream.
GLUCONEOGENESIS - formation of glucose from non-carbohydrate sources, e.g amino acids + glycerol (from lipids)
What’s gluconeogenesis
GLUCONEOGENESIS - formation of glucose from non-carbohydrate sources, e.g amino acids + glycerol (from lipids)
What’s glycogenolysis
GLYCOGENOLYSIS - hydrolysis of glycogen in liver & muscle cells to release glucose into bloodstream.
What’s glycogenesis.
GLYCOGENESIS - formation of glycogen from excess glucose
In what ways does insulin decrease blood glucose levels
increase rate of glycogenesis
increase respiratory rate of cells
increase rate of glucose to fat conversion
inhibits release of glucagon from alpha cells
How does glucagon increase BGC
increases rate of glycogenolysis
reduce amount of glucose absorbed by liver cells
increase rate of gluconeogenesis
What’s a normal blood glucose conc
90mg/100cm3
What’s a the mechanism of insulin release by beta cells
1.at normal BGC, K+ channels in plasma membrane of beta cells are open, membrane is at resting potential.
2.BGC rises, glucose enters cell by glucose transporter
3.metabolised into ATP by aerobic respiration by mitochondria
4.ATP binds to ATP sensitive K+ channels, causing them to close
5.K+ cannot diffuse out, so membrane depolarised to approx -30mV
6.Causes voltage-gated Ca2+ channels to open
7.Ca2+ ions enter cell, cause secretory vesicles to release insulin by exocytosis
What cells contain insulin receptors on their plasma membrane
every cell.
since every cell requires glucose to move in
so that it can be respired for energy/ATP.
Which cells contain glucagon receptors
only liver & muscle cells.
∵ they store glycogen, so respond to glucagon.
How is the role of insulin an example of negative feedback
As blood glucose concentrations return back to normal detected by the b cells in the pancreas, the b cells reduce their secretion of insulin. This ensures that the insulin is set back to its normal level.
What is the role of glucagon an example of negative feedback
As blood glucose concentrations return to normal, this is detected by the a cells of the pancreas. when it rises above a set level, the a cells reduce their level of secretion of glucagon and returns it back to its normal level.
What happens when there’s a fall in blood glucose conc
Alpha cells detect the fall in BGC and they produce glucagon and inhibit the production of insulin
The glucagon converts glycogen to glucose and aa to glucose therefore BGC rises
What happens when there’s a rise in BGC
Beta cells detect this rise and stimulate the production of insulin and inhibit the production of glucagon
They increase cellular respiration
Convert glucose to glycogen
Glucose to fat
Absorption of glucose into cells
