14.3 Regulation of Blood Glucose Concentration

Question 1

What are the processes of decreasing glucose concentration?

Answer 1

RESPIRATION - uses glucose as reactant to form ATP

GLYCOGENESIS - formation of glycogen from excess glucose

Question 2

What are the processes of increasing blood glucose concentration?

Answer 2

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)

Question 3

In what ways does insulin decrease blood glucose levels?

Answer 3

increase rate of glycogenesis

increase respiratory rate of cells

increase rate of glucose to fat conversion

inhibits release of glucagon from alpha cells

Question 4

How does glucagon increase blood glucose concentration?

Answer 4

increases rate of glycogenolysis

reduce amount of glucose absorbed by liver cells

increase rate of gluconeogenesis

Question 5

What is the normal blood glucose concentration?

Answer 5

90mg/100cm³

Question 6

What is the mechanism of insulin release by beta cells?

Answer 6

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

Question 7

What cells contain insulin receptors on their plasma membrane?

Answer 7

every cell.

since every cell requires glucose to move in

so that it can be respired for energy/ATP.

Question 8

What cells contain glucagon receptors?

Answer 8

only liver & muscle cells.

∵ they store glycogen, so respond to glucagon.