14.3 Regulation Of Blood Glucose Concentration

Question 1

What are the reasons for an increase in blood glucose concentration

Answer 1

Diet - high carb intake
Glycogenolysis - glycogen in liver and muscle breakdown into glucose

Gluconeogenesis - production of glucose from non carbohydrate sources

Question 2

What is the reason for a decrease in blood glucose

Answer 2

Respiration uses it to release energy

Glycogenesis - production of glycogen

Question 3

What is the role of insulin

Answer 3

When blood glucose is too high B cells will detect and secrete insulin into the bloodstream
They will bind to glycoprotein receptors causing all glucose transport channels to open allowing more
Glucose to enter

Question 4

What happens when insulin opens all glucose transport proteins channels

Answer 4

Increases glucose absorption 
Increases respiratory rate of cells 
Increases glycogenesis 
Increasing glucose to fat conversion 
Inhibits release of glucagon

Question 5

What is the role of glucagon

Answer 5

If blood glucose is too low then A cells secrete glucagon into bloodstream

Question 6

What cells in the body have glucagon receptors

Answer 6

Only liver and fat cells

Question 7

What happens when glucagon is released into Bloodstream

Answer 7

Glycogenolysis - liver breaks down glycogen to Glucose
Reduced absorption of glucose by liver
Gluconeogensis is increased
Amino acids + glycerol make glucose

Question 8

What is happening in B cells when blood glucose is at a normal level

Answer 8

Potassium channels in membrane of B cells are open

The potential is at -70mV

Question 9

What happens in B cells when BGC rises

Answer 9

Glucose enters the cell by a glucose transporter and the glucose is metabolised inside the mitochondria producing ATP
This ATP binds to potassium channels and causes them to close - ATP sensitive potassium channels

Question 10

What happens when the potassium channels are closed by ATP in B cells when BGC rises

Answer 10

Potassium no longer diffuses out of the cell and the potential difference reduces to -30mV so depolarisation occurs

Question 11

What happens when depolarisation of B cells occur due to potassium channels closing from increase in BGC

Answer 11

Voltage gates calcium ions open and calcium enters the cell causing secretory vesicles to release insulin by exocytosis