6.4.2 Control Of Glucose Conc

Question 1

Factors that influence blood glucose levels

Answer 1

Consumption of carbs - more glucose in blood

Rate of respiration of glucose - increase during exercise

Question 2

Process involved in changing glucose to and from glycogen and glycerol + amino acids to glucose

Answer 2

Glycogen - glucose = glycogenolysis
Glucose - glycogen = glycogenesis

Glycerol + amino acids - glucose = gluconeogenesis

Question 3

Decreasing blood glucose including glycogenesis

Answer 3

Beta cells in pancreas’s detect blood glucose is to high and secrete insulin

Insulin attaches to specific receptors on cell surface membrane of target cells (liver/muscles):
-this causes more glucose channel proteins to join cell surface membrane, increasing permeability, so more glucose moves in via facilitated diffusion

• it also activates enzymes involved in the conversion of glucose to glycogen (glycogenesis), this lowers glucose conc ingests creating a gradient, glucose enters cells via facilitated diffusion

Question 4

Action of glucagon in increasing blood glucose conc

Answer 4

Alpha cells in pancreases detect blood glucose is to low and secrete glucagon

Glucagon attaches to specific receptors on cells (liver)
-this actives enzymes involved in hydrolysis of glycogen to glucose (glycogenolysis)
-also actives enzymes involved in conversion of glycerol + amino acids to glucose (gluconeogenesis)

This establishes a conc gradient - glucose enters blood via facilitated diffusion

Question 5

Role of adrenaline in blood glucose level

Answer 5

Stress increases the secretion of adrenaline from adrenal glands

This attaches to specific receptors on cells (liver)
This activates enzymes involved involved in the hydrolysis of glycogen to glucose (glycogenolysis)
-establishing a conc gradient so glucose enters the cells via facilitated diffusion

Question 6

2nd messenger model of adrenaline and glucagon

Answer 6

Glucagon and adrenaline attach to receptors on cells via membrane (first messengers)

This actives enzyme adenylate cyclase
-this converts many ATP to many cyclic AMP (cAMP)
-cAMP acts as a 2nd messenger, activating protein kinase enzymes
-protein kinase enzymes breaks down glycogen to glucose

Question 7

Advantages of 2nd messenger model

Answer 7

Amplifies signal from hormone
As each hormone can stimulate many molecules of cAMP
Which can actives many enzymes for a rapid increase in glucose

Question 8

Type 1 vs type 2 diabetes

Answer 8

Both - higher and have higher peaks of glucose after a meal and it remains high

Type 1:
-B cells produce insufficient insulin
-develops in childhood due to autoimmune response destroying B cells

Type 2:
-receptors lose sensitivity to insulin
-fewer glucose transport proteins so less uptake of glucose, less conversion of glucose to glycogen
-risk= obesity

Question 9

How can type 1 be controlled

Answer 9

Injections of insulin
Blood glucose measured with biosensors, a dose of insulin is matched to glucose intake
-eat regular and control carb intake, to bond sudden rise

Question 10

Why can’t insulin be taken as a table (mouth)

Answer 10

Insulin is a proteins and would be hydrolysed by endopeptodases

Question 11

How can type 2 be controlled

Answer 11

Drugs increasing receptor sensitivity can be injected, to increase glucose uptake

Reduce sugar intake so less is absorbed

Reduce fat intake (less glycerol converted into glucose)

More exercise - uses glucose in respiration

Lose weight - increased sensitivity of receptors