control of blood glucose concentration

Question 1

which organ monitors blood glucose concentration?

Answer 1

the pancreas

Question 2

list examples of factors which affect blood glucose concentration

Answer 2

1. blood glucose concentration increases after eating food containing carbohydrates
2. blood glucose concentration decreases after exercise as glucose is a respiratory substrate used up in respiration to release energy (ATP)

Question 3

which hormones in the hormonal system control blood glucose concentration

Answer 3

1. insulin
2. glucagon

Question 4

explain where insulin is secreted in the body

Answer 4

• in the pancreas
• in the islets of Langherhans
• by Beta cells
• into the blood

Question 5

explain where glucagon is secreted in the body

Answer 5

• in the pancreas
• in the islets of Langherhans
• by alpha cells
• into the blood

Question 6

what is the function of insulin

Answer 6

insulin lowers blood glucose concentration when its too high by acting on effectors

Question 7

outline the action of insulin

Answer 7

1. insulin attaches/binds to receptors on surfaces of target cells (cell membranes of liver cells and muscle cells)
2. increasing the membrane permeability of target cells to glucose by increasing the number of channel proteins in the cell membranes, so more glucose diffuses into cell
3. insulin activates enzymes in the liver and muscle cells that convert glucose into glycogen via glycogenesis
4. insulin increases the rate of respiration of glucose in muscle cells

Question 8

what is the function of glucagon

Answer 8

glucagon increases blood glucose concentration when its too low by acting on effectors

Question 9

outline the action of glucagon

Answer 9

1. glucagon attaches/binds to receptors on the cell membranes of target cells (liver cells)
2. glucagon activates enzymes in the liver cells that break down glycogen into glucose via glycogenolysis
3. glucagon activates enzymes involves in the formation of glucose from glucerol and amino acids via gluconeogenesis
4. glucagon decreases the rate of respiration of glucose in cells

Question 10

explain why hormonal response is slower than the nervous response but lasts longer

Answer 10

• hormones travel in the blood to their target cells so they are slower
• hormones are not broken down as quickly as neurotransmitters so their effects last longer

Question 11

explain the role of the liver in glycogenesis

Answer 11

converts glucose into glycogen by secreting insulin

Question 12

explain the role of the liver in glycogenolysis

Answer 12

converts glycogen into glucose by secreting glucagon

Question 13

explain the role of the liver in gluconeogenesis

Answer 13

converts non-carbohydrates (like glycerol and amino acids) into glucose by secreting glucagon

Question 14

name an example of a glucose transporter

Answer 14

GLUT4

Question 15

outline how glucose moves through a glucose transporter

Answer 15

• when insulin levels are low, GLUT4 is stored in vesicles of cytoplasm cells
• when insulin binds to receptors on the cell surface membrane, it triggers the movement of GLUT4 to the membrane
• glucose is transported into the cell through the GLUT4 protein via facilitated diffusion

Question 16

outline the role of adrenaline

Answer 16

• adrenaline binds to receptors in the cell membrane of (target cells) liver cells
• it activates enzymes involved in glucogenolysis (breakdown of glycogen into glucose)
• it inhibits enzymes involved in glycogenesis (synthesis of glycogen from glucose)
• activates glucagon secretion and inhibits insulin secretion to increase glucose concentration

Question 17

where is adrenaline secreted

Answer 17

secreted from adrenal glands

Question 18

where is adrenaline secreted

Answer 18

secreted from adrenal glands

Question 19

what is the function of adrenaline

Answer 19

increases blood glucose concentration

Question 20

explain how adrenaline prepares the body for action

Answer 20

• glucose is a respiratory substrate
• by making more glucose available for muscles to respire

Question 21

what hormones act as secondary messengers

Answer 21

1. adrenaline
2. glucagon

Question 22

what makes adrenaline and glucagon secondary messengers

Answer 22

they can activate glycogenolysis inside a cell by binding to receptors on the outside of the cell

Question 23

outline the second messenger model

Answer 23

1. the receptors for adrenaline and glucagon have specific tertiary structures, making the complementary in shape to their respective hormones
2. adrenaline/glucagon bind to their receptors and activate the enzyme adenylate cyclase
3. activated adelyate cyclase converts ATP into cyclic AMP (cAMP)
4. CAMP activates an enzyme called protein kinase A
5. protein kinase A activates glycogenolysis

Question 24

when do diabetes occur

Answer 24

when blood glucose concentration is not controlled

Question 25

what is the cause of diabetes type I

Answer 25

- the immune system **attacks the beta cells** in the islets of Langerhans - so they can’t produce any insulin

Question 26

what are the treatments for type I diabetes

Answer 26

- insulin therapy = regular insulin injections throughout the day or an insulin pump - eating regularly and controlling simple carbohydrate intake to avoid a sudden rise in glucose

Question 27

what is the cause of diabetes type II

Answer 27

- beta cells don’t produce enough insulin - or body cells do not respond to insulin due to malfunction in receptors on their membranes so not enough glucose is taken up

Question 28

what are the treatments for type II diabetes

Answer 28

- eating a healthy, balanced diet, losing weight and regular exercise - glucose-lowering medication - insulin injections

Question 29

evaluate the treatments type II diabetes

Answer 29

- NHS’s campaigns like Change4Life aim to educate people on having a healthier diet and lifestyle so reduce risk of development of conditions like diabetes II - health advisors challange the food industry to reduce the advertising of fast food, to improve the nutritional value of their products and to use clearer labelling on products so consumers can make healthier choices - food companies have attempted to make their products more healthy by using sugar alternatives or reducing the sugar, fat and salt content of the food but there is pressure on companies to increase profits

Question 30

how do you measure the concentration of a glucose solution

Answer 30

1. **Add Benedict’s reagent** and **heat** with glucose, initial blue colour is lost but a **brick-red precipitate is not produced** 2. use **colorimeter** to measure **light absorbance of solution** 3. the **higher the concentration the more blue colour will be lost**, **decreasing the absorbance of the solution**