Regulation of blood glucose concentration

Question 1

Protein hormones

Answer 1

• Binds to receptor on the plasma membrane
  = Conformational change
• Initiating production of enzyme adenylyl cyclase
  = Cells converts ATP into cyclic adenosine monophosphate (cAMP)
• Activates enzymes to carry out normal function

Question 2

The pancreas

Answer 2

• Mainly made up of cells that produce digestive enzymes; amylase, lipase and protease.
• Hormone producing cells called islets of Langerhans - involved in the regulation of blood glucose levels

Question 3

Islets of Langerhans

Answer 3

• Glucagon hormone produced by a cells - larger

- Insulin hormone produced by B cells - smaller

Question 4

Three important processes

Answer 4

1 - Glycogenesis
2 - Glycogenolysis
3 - Gluconeogenesis

Question 5

Glycogenesis

Answer 5

• Conversion of glucose into glycogen
• Happens when blood glucose levels are higher than normal
• Liver removes glucose from the blood
• Converts it into glycogen for storage

Question 6

Glycogenolysis

Answer 6

• Breakdown of glycogen to glucose

- Happens in the liver when blood glucose levels are lower than normal

Question 7

Gluconeogenesis

Answer 7

• Production of glucose from sources other than carbohydrates;
  Amino acids
  Glycerol

Question 8

Why is it important for organisms to maintain the correct level of glucose in the blood

Answer 8

• Maintain water potential of cells and metabolism

- So cells don’t shrivel or burst

Question 9

Normal blood glucose concentration

Answer 9

5 mmol dm-3

Question 10

3 sources of glucose for the blood

Answer 10

1. Diet - direct glucose or hydrolysed carbohydrate
2. Glycogenolysis - hydrolysis of glycogen
3. Gluconeogenesis - production of glucose from sources other than carbohydrates

Question 11

Fluctuation

Answer 11

• Depending on diet and activity levels (respiration rates)

- Positive and negative feedback

Question 12

Beta cells of islets of Langerhans

Answer 12

• Receptors that detect high blood glucose levels
• Secrete insulin directly into the blood
• Transported in blood plasma until it reaches a cell with complementary receptors on its surface
  = Insulin receptor complex

Question 13

The effect of insulin

Answer 13

• Glucose transport carrier proteins change shape and open allowing more glucose to move through them by F.D into the cell
• Enzymes involved in conversion of glucose to glycogen and fat are activated
• More glucose transport channels are created

Question 14

Negative feedback - insulin

Answer 14

• Stop the secretion of insulin once the blood glucose level returns to normal

Question 15

Importance of an increased glucose uptake

Answer 15

• Water potential of the blood is maintained

Question 16

Importance of an increased respiratory rate

Answer 16

• Use the glucose in respiration which will lower the glucose levels and provide you with more energy (ATP)

Question 17

Importance of an increased glycogenesis

Answer 17

• Reduces blood sugar levels

- Acts as a store for glycogen for later activity

Question 18

Importance of an increased lipogenesis

Answer 18

• Creation of fats

- Store of glucose when blood sugar levels are low

Question 19

The role of glucagon

Answer 19

• Alpha cells of the islets of Langerhans have receptors that detect low blood glucose levels
• Secrete glucagon directly into the blood which is transported in the blood plasma until it reaches a cell with complementary receptors on its surface
• Glucagon receptor complex is formed

Question 20

The effect of glucagon

Answer 20

• Activates enzymes that convert glycogen to glucose

- Activates enzymes that convert amino acids and glycerol into glucose GLUCONEOGENESIS

Question 21

Negative feedback - effect of glucagon

Answer 21

• Stop the secretion of glucagon once the blood glucose level returns to normal

Question 22

Adrenaline

Answer 22

• Regulates blood glucose levels - stress and excitement
• Adrenaline secreted from adrenal gland

1. Adrenaline attaches to complementary protein receptors on the cell surface membrane of target cells
2. Activates enzymes - breakdown of glycogen to glucose in the liver
3. Respiration rate increases

Question 23

Blood glucose level rises

Answer 23

• Beta cells in pancreas releases insulin into the blood
• Liver takes up glucose and stores it as glycogen
• Blood cells take up glucose
• Blood glucose levels decline
• Homeostasis

Question 24

Blood glucose levels falls

Answer 24

• Alpha cells in pancreas release glucagon
• Liver breaks down glycogen and releases glucose
• Blood glucose level rise
• Homeostasis