3.6.4.2 Control of blood glucose concentration

Question 1

definition of glycogenesis

Answer 1

glucose to glycogen conversion

Question 2

definition of glycogenolysis

Answer 2

glycogen to glucose conversion

Question 3

definition of gluconeogenesis

Answer 3

amino acids/glycerol to glucose conversion

Question 4

how is insulin secreted and when

Answer 4

secreted by Beta cells in islets of Langerhans in pancreas when they detect low glucose levels

Question 5

how does insulin decrease blood sugar levels (two ways)

Answer 5

1.) Attaches to specific receptors on cell surface membrane of liver and muscle cells (target cells )
More glucose channel proteins join cell surface membrane
increases permeability to glucose
glucose enters via facilitated diffusion
2.)activates enzymes which converts glycogenesis
lowering glucose concentration in cells creating concentration gradient
so glucose enters via facilitated diffusion

Question 6

how is glucagon secreted and when

Answer 6

alpha cells in islets of langerhans in pancreas detect blood glucose concentration is too low and secretes glucagon

Question 7

how does glucagon help increase blood glucose concentration

Answer 7

attaches to specific receptors on cell surface membranes of target cells/ liver
activates enzyme for glycogenolysis and gluconeogenesis
establishes conc gradient so glucose enters blood via facilitated diffusion

Question 8

how does adrenaline increase blood glucose concentration

Answer 8

attaches to specific receptors on cell surface membranes of target cells /liver
activates enzymes involved in glycogenolysis
establishes conc gradient glucose enters blood via facilitated diffusion

Question 9

Describe the second messenger model of adrenaline and glucagon action

Answer 9

1. activates enzyme adenylate cyclase
2. which converts many ATP to many cyclic AMP
3. cAMP acts as second messenger which activates protein kinase enzymes
4. Protein kinases activates enzymes to break down glycogen to glucose

Question 10

Advantages of second messenger model

Answer 10

amplifies signal from hormone
as each hormone can stimulate production of many molecules of cAMP
which can activate many enzymes for rapid increase in glucose

Question 11

Causes of type 1 diabetes

Answer 11

b cells in islets of langerhans in pancreas produce insufficient insulin
develops in childhood due to autoimmune response destroying b cells

Question 12

causes of type 2 diabetes

Answer 12

faulty recpetor loses responsiveness to insulin
fewer glucose transport proteins so less uptake of glucose so less conversion of glucose to glycogen

Question 13

How could type 1 diabetes be controlled

Answer 13

insulin injections
blood glucose conc monitored with biosensors so dose of insulin matches to glucose intake
control carbohydrate intake - ones that can be absorbed slower
avoid sudden rise in glucose

Question 14

why cant insulin be taken as a tablet by mouth

Answer 14

is a protein so would be hydrolysed by endopeptidases and exopeptidase