14.3 Regulation of Blood Glucose Concentration

Question 1

Why is controlling blood glucose concentration important?

Answer 1

Too low- not enough glucose for respiration and producing ATP which is important for many biological processes.

Question 2

What is the normal blood glucose concentration + units?

Answer 2

90mgcm-3

Question 3

What causes blood glucose concentration to increase?

Answer 3

Diet
Glycogenolysis
Gluconeogenesis

Question 4

What is glycogenolysis?

Answer 4

Glycogen stored in liver and muscles is broken down into glucose (and released into the blood stream).

Question 5

What is gluconeogenesis?

Answer 5

Production of glucose from non-carbohydrate sources.

Question 6

What causes blood glucose concentration to decrease?

Answer 6

Respiration
Glycogenesis

Question 7

What is glycogenesis?

Answer 7

Production of glycogen (from glucose) to be stored in the liver.

Question 8

Where is insulin produced?

Answer 8

islets of Langerhans beta cells

Question 9

How does insulin make cells absorb more glucose?

Answer 9

There are insulin receptors on nearly all body cells.
When insulin bonds it changes the shape of the Gliwice transport protein channels, making them open.
More glucose enters the cells.

Question 10

What does insulin ‘activate’?

Answer 10

An enzyme which converts glucose to glycogen.

Question 11

Insulin lowers blood glucose concentration by: (5 things)

Answer 11

Increasing rate of respiration
Increasing rate of absorption of glucose by cells
Increasing glycogenesis
Increasing glucose to fat conversion
Inhibiting the release of glucagon

Question 12

Which cells have glucagon receptors?

Answer 12

Liver and fat cells

Question 13

Glucagon raises blood glucose concentration by: (3 things)

Answer 13

Glycogenolysis
Reducing the amount of glucose absorbed by the liver cells
Increasing gluconeogenesis

Question 14

How does being stressed affect blood glucose concentration?

Answer 14

Adrenaline is released
This raises the blood glucose concentration so more respiration can take place

Question 15

Are K+ ion channels open or closed normally, and what does this mean?

Answer 15

Open, so K+ ions diffuse out of cell.

Question 16

What is the potential difference of a cell, relative to the inside, normally?

Answer 16

-70mV

Question 17

What happens with insulin secretion when stimulated by glucose?

Answer 17

1. Blood glucose rises and it enters the cell by a glucose transporter
2. Glycogenesis is metabolised in the mitochondria and ATP is produced
3. ATP binds to K+ channels, so the channels close
4. K+ cannot diffuse out of cell now so the potential difference reduces to -30mV and depolarisation occurs
5. The depolarisation causes voltage gated channels to open
6. Ca2+ enter the cell and Casey secretory vesicles to release the insulin they contain (via exocytosis)