3.6.4.2 Control of Blood Glucose Concentration

Question 1

What is the difference in speed between the nervous and hormonal system?

Answer 1

The nervous system is faster than the hormonal system

Question 2

What are the characteristics of hormones?

Answer 2

Produced in the glands
Carried in the blood plasma to the cells on which they act (target cells)
Are effective in low concentrations but have long lasting effects

Question 3

What is the mechanism involving adrenaline?

Answer 3

Adrenaline binds to a transmembrane protein receptor within the cell surface membrane of a liver cell
The binding of adrenaline causes the protein to change shape
The change of protein shape leads to the activation of an enzyme called adenyl cyclase. The activated adenyl cyclase converts ATP to cyclic AMP (cAMP)
The cAMP in turn changes the shape and activates protein kinase enzyme
The active protein kinase enzyme catalyses the conversion of glycogen to glucose

Question 4

What are the groups of hormone producing cells known as?

Answer 4

Islets of Langerhans

Question 5

What are the two types of cells in the islets of langerhans?

Answer 5

Alpha: larger and produces the hormone glucagon
Beta: smaller and produces the hormone insulin

Question 6

What are the three process in the regulation of blood sugar? (No explanation)

Answer 6

Glycogenesis
Glycogenolysis
Gluconeogenesis

Question 7

What is glycogenesis?

Answer 7

The conversion of glucose into glycogen
When blood glucose concentration is higher than normal the liver removes glucose from the blood and converts it to glycogen

Question 8

What is glycogenolysis?

Answer 8

The breakdown of glycogen to glucose
When blood glucose concentration is lower than normal, the liver can convert stored glycogen back into glucose which diffuses into the blood to restore the normal blood glucose concentration

Question 9

What is gluconeogenesis?

Answer 9

The production of glucose from sources other than carbohydrate
When its supply of oxygen is exhausted, the liver can produce glucose from non-carbohydrate sources such as glycerol and amino acids

Question 10

Why do hormones only affect target cells?

Answer 10

Because only target cells have the specific protein receptors that are complementary to the shape of that specific hormone

Question 11

What occurs if the blood glucose concentration is too high?

Answer 11

It lowers the water potential of the blood and causes dehydration

Question 12

What occurs if the blood glucose concentration is too low?

Answer 12

Cells will be deprived of energy and die

Question 13

What are the factors which increase glucose concentration?

Answer 13

Your diet where glucose is absorbed via the absorption of carbohydrates
From the hydrolysis in the small intestine of glycogen (glycogenolysis)
From gluconeogenesis

Question 14

What are the three main hormones involved in the regulation of blood glucose concentration?

Answer 14

Insulin, glucagon and adrenaline

Question 15

What do B cells of the pancreas do?

Answer 15

They have receptors which detect the stimulus of a rise in blood glucose concentration
Then they respond by secreting the hormone insulin directly into the blood plasma

Question 16

What type of molecule is insulin?

Answer 16

A globular protein

Question 17

What does insulin bind to?

Answer 17

Insulin bind specifically to glycoprotein molecules on the cell surface membranes of body cells

Question 18

What does insulin cause when it binds to receptors on body cells?

Answer 18

A change in the tertiary structure of the glucose transport carrier proteins, causing them to change shape and open, allowing more glucose into the cells via facilitated diffusion
An increase in the number of carrier proteins responsible for glucose transport. At low insulin concentrations, the protein from which these channels are made is part of the membrane of vesicles. A rise in insulin concentration results in these vesicles fusing with the cell-surface membrane so increasing the number of glucose transport channels
Activation of the enzymes that convert glucose to glycogen and fat

Question 19

How does the lowering of blood glucose affect B cells?

Answer 19

Their secretion of insulin reduces

Question 20

What is the function of the alpha cells of the islets of Langerhans?

Answer 20

They detect a fall in blood glucose concentration and respond by secreting the hormone glucagon directly into blood plasma

Question 21

What are the effects of glucagon in the blood?

Answer 21

It attaches to specific protein receptors on the cell surface membrane of liver cells
It activates enzymes that convert glycogen to glucose
Activates enzymes involved in the conversion of amino acids and glycerol into glucose (gluconeogenesis)

Question 22

How does the raising of blood glucose affect alpha cells?

Answer 22

It causes the alpha cells to reduce the secretion of glucagon

Question 23

What is the role of adrenaline in regulating the blood glucose level?

Answer 23

Adrenaline increases the blood glucose concentration
It does this by:
Attaching to protein receptors on the cell-surface membrane of target cells
Activating enzymes that causes the breakdown of glycogen to glucose in the liver

Question 24

What is diabetes?

Answer 24

A disease in where a person is unable to metabolise carbohydrate, especially glucose, properly

Question 25

What are the two types of diabetes? (No explanation)

Answer 25

Type I and type II

Question 26

What is type I diabetes?

Answer 26

Insulin dependent

Due to the body being unable to produce insulin

Question 27

What is type II diabetes?

Answer 27

Insulin independent
Normally due to glycoprotein receptors on body cell being lost or losing their responsiveness to insulin
It may also be due to an inadequate supply of insulin from the pancreas

Question 28

What are the treatment options for type I diabetes?

Answer 28

Controlled by injections of insulin
The dose of insulin must be matched exactly to the glucose intake
To ensure the correct dose, blood glucose concentration is monitored using biosensors

Question 29

What are the treatment options for type II diabetes?

Answer 29

By regulating the intake of carbohydrate in the diet and matching this to the amount of exercise taken
And in some cases, injecting insulin and using drugs to slow down the rate at which glucose is absorbed

Question 30

What are the two stages of the control of blood glucose concentration?

Answer 30

Low blood sugar: glucagon, hydrolyses glycogen bonds, glycogenolysis
High blood sugar: insulin, adds glucose to glycogen, creates glycosidic bonds, glucogenesis