Control Of Blood Glucose Concentration

Question 1

What is the danger of blood glucose being too high?

Answer 1

• Alters water potential of blood, affecting concentration gradients. Draws water out of cells leading to severe dehydration

Question 2

What is the danger of blood glucose being too low?

Answer 2

• Cells are lacking glucose for respiration, and with no energy being released, they might die

Question 3

What is the normal blood glucose?

Answer 3

• 5 mmol dm-3 blood

Question 4

Blood glucose too high step 1

Answer 4

• Detected by beta cells of the pancreas, from a region known as the islets of langerhans

Question 5

Blood glucose too high step 2

Answer 5

• Insulin secreted directly into blood plasma - it binds to glycoprotein receptors found on nearly all cells except RBC’s

Question 6

Blood glucose too high step 3

Answer 6

• Triggers increased cellular respiration to metabolise glucose

Question 7

Blood glucose too high step 4

Answer 7

• Enzymes activated causing conversion of glucose to fat, & glucose to glycogen in cells of liver and muscle (glycogenesis)

Question 8

Blood glucose too high step 5

Answer 8

• At target cells in liver and skeletal muscle: When insulin binds to its receptor proteins on the cell-surface membrane, vesicles in the cell with embedded glucose carrier proteins fuse with the cell-surface membrane (inserting these proteins into the membrane!) The carrier proteins now allow glucose to enter the cell via facilitated diffusion

Question 9

Blood glucose too high step 6

Answer 9

• Blood glucose falls to normal – negative feedback reduces insulin secretion

Question 10

Blood glucose too low step 1

Answer 10

• Detected by alpha cells of the pancreas, from a region known as the islets of langerhans

Question 11

Blood glucose too low step 2

Answer 11

• Glucagon secreted directly into blood plasma. Receptors only found on hepatocytes (liver cells)

Question 12

Blood glucose too low step 3

Answer 12

• Enzyme becomes activated to help convert glycogen to glucose (glycogenolysis) + convert amino acids and other non-carbohydrates to glucose (gluconeogenesis)

Question 13

Blood glucose too low step 4

Answer 13

• Trigger glucose entry from intestines

Question 14

Blood glucose too low step 5

Answer 14

• Blood glucose rises to normal – negative feedback reduces glucagon secretion

Question 15

Why do pupils dilate when adrenaline released?

Answer 15

• Pupils dilate in the eyes to…let more light into the eye/retina; to see danger

Question 16

Why does heart rate increase when adrenaline released?

Answer 16

• Heart rate increases to…deliver more oxygen; and more glucose to the muscles

Question 17

Why does breathing rate increase when adrenaline is released?

Answer 17

• Breathing rate increases to…deliver more blood to the lungs

Question 18

Why do small arteries in the intestine narrow when adrenaline is released?

Answer 18

• Small arteries in the intestine narrow to…divert more blood to the leg muscles

Question 19

Why does glycogen get converted back to glucose in the liver when adrenaline is released?

Answer 19

• Glycogen gets converted back to glucose in the liver to…provide more glucose; greater rate of respiration (less anaerobic respiration/lactic acid produced); provide more ATP; so, you can run faster/muscles contract more

Question 20

What do adrenals do?

Answer 20

• Stimulates glycogenolysis and inhibits glycogenesis (works antagonistically to insulin)

Question 21

Secondary messenger model step 1

Answer 21

• the hormone adrenaline approaches transmembrane protein

Question 22

Secondary messenger model step 2

Answer 22

• adrenaline fuses to the receptor causing it to change shape on the inside of the membrane activating an enzyme called adenyl cyclase inside the membrane

Question 23

Secondary messenger model step 3

Answer 23

• the activated adenyl cyclase converts ATP to cyclic AMP, which acts as a second messenger

Question 24

Secondary messenger model step 4

Answer 24

• the cAMP in turn changes the shape of and activates protein kinase enzyme

Question 25

Secondary messenger model step 5

Answer 25

• the active protein kinase enzyme catalyses the conversion of glycogen to glucose

Question 26

What is type 1 diabetes?

Answer 26

• insulin dependant
• mainly in young people
• autoimmune attack on pancreas therefore body doesn’t produce insulin, and so glucose can’t be taken into the cells

Question 27

What is type 2 diabetes?

Answer 27

• insulin independent
• mainly in adults
• glycoprotein receptors less responsive to insulin (possibly due to low supply from pancreas)

Question 28

What are the effects of diabetes?

Answer 28

• hyperglycaemia (too much blood sugar) can lead to dehydration
• extreme thirst - weight loss
• long term can damage blood vessels in retina
• glucose in the urine
• can damage kidneys and nerves
  *too low sugar if inject too much or miss meal can lead to nausea, sweating and unconsciousness

Question 29

What are the treatments of type 1 diabetes?

Answer 29

• regular insulin injections (2-4 times daily); not by mouth as would be digested.
• regular monitoring of blood sugar levels by biosensors to ensure correct dose administered

Question 30

What are the treatments of type 2 diabetes?

Answer 30

• healthy diet (right amounts of sugar) + regular exercise
• possible option of taking drugs to reduce rate at which glucose is absorbed by the body