Diabetes

Question 1

How is glucose stored

Answer 1

As glycogen (when there is an abundance of glucose)

Question 2

Glucose storage when maximum level of glycogen is reached

Answer 2

glucose still enters cells via GLUT4 but is broken down to fatty acids and stored as fats

Question 3

where is glucose stored

Answer 3

liver (mainly) and muscles

Question 4

mechanism of glucose homeostasis after a meal (4)

Answer 4

increased glucose absorption which may stimulate metabolism
increased glucose concentration in circulation
insulin is released
increased oxygen demand

Question 5

mechanism of glucose homeostasis in between meals (4)

Answer 5

glucose absorption is minimal
which lowers glucose concentration in circulation
limited metabolism
decreased oxygen demand

Question 6

What happens when glucose conc increased in blood (6)

Answer 6

increased glucose conc in beta cells of pancreas
= increased ATP conc produced by beta cells
high internal ATP = K+ channels close
= membrane potential is depolarised
= Ca2+ channels open
= beta cells secrete insulin

Question 7

what is insulin produced by

Answer 7

beta cells

Question 8

major target of insulin

Answer 8

liver

Question 9

roles of insulin (4)

Answer 9

promotes uptake and storage of glucose
promotes synthesis of new proteins
promotes use of glucose as metabolic substrate
promotes storage of fat as triglycerides

Question 10

how does insulin promote uptake and storage of glucose (4)

Answer 10

1. insulin activates P13K
2. P13K activates protein kinase B (PKB)
3. PKB activates GLUT4
4. GLUT4 allows entry of glucose into hepatocyte

Question 11

how does insulin promote synthesis of new proteins (4)

Answer 11

1. insulin binds to insulin receptor
2. receptor activates P13K
3. P13K activates TORC1
4. TORC1 activates protein synthesis

Question 12

Role of glucagon (2)

Answer 12

promotes gluconeogenesis to convert lipids and amino acids in glucose
promotes glucose release from glycogen stores (mainly liver)

Question 13

what is glucagon produced by

Answer 13

alpha cells

Question 14

glucagon dominates between meals (fasting state) and increases… (3)

Answer 14

glycogenolysis
gluconeogenesis
ketogenesis

Question 15

insulin dominates after a meal (fed state) and increases… (4)

Answer 15

glycogen synthesis
protein synthesis
fat synthesis
glucose oxidation

Question 16

how does insulin promote storage of fat as triglycerides

Answer 16

inactivates lipase which normally converts triglycerides to 3 fatty acids and glycerol
glucose is metabolised to glycerol and free fatty acids enter the adipocyte cell where they combine to form triglycerides

Question 17

how does glucagon promote glucose release from glycogen stored

Answer 17

signal transduction pathway which is G-protein coupled
this activates cAMP/PKA-dependent signalling pathway

glucagon receptor = G-protein coupled receptor

Question 18

what is glucagon release stimulated by (3)

Answer 18

hypoglycaemia
vigorous exercise
increased levels of amino acids

Question 19

Glucagon role during starvation (hypoglycaemia)

Answer 19

1. Glycogen stores used to increase glucose levels
2. Glucagon stimulates formulation of glucose from lipids and amino acids (gluconeogenesis) by promoting lipid and protein degradation

Question 20

symptoms of hyperglycaemia

Answer 20

weak
tired itchy dry skin 
frequent urination 
increased thirst 
decreased appetite 
blurry vision
fruity breath - ketones present

Question 21

symptoms of hypoglycaemia

Answer 21

nervous 
irritability 
shaky 
dizzy 
hunger 
headache 
confused 
increased HR

Question 22

what is type 1 diabetes

Answer 22

failure of insulin secretion from autoimmune destruction of beta cells
mediated by CD8 cytotoxic T-cells which recognise peptides from beta-cell specific protein and kills it

usually develops in early life

Question 23

what is type 2 diabetes

Answer 23

insulin present in circulation but glucose conc remains high

usually develops later in life

Question 24

obesity link in type 2 diabetes (6)

Answer 24

obesity leads to adipokines, free fatty acids and inflammation
= all 3 lead to insulin resistance in tissues
= beta cell compensation
= beta cell failure
= decreased insulin secretion
= type 2 diabetes

Question 25

what is gestational diabetes

Answer 25

develops during pregnancy but tends to disappear after birth
beta cells cant produce enough insulin to meet the extra needs in pregnancy

Question 26

possible consequences of gestational diabetes (5)

Answer 26

increased BP 
jaundice after birth 
increased risk of T2D development in future 
premature birth 
baby growing larger than normal

Question 27

first line treatment for type 2 diabetes and general pharmacology (3)

Answer 27

metformin

activates AMPK (regulates lipid and glucose metabolism)
increases lypolysis in liver and muscles = improves insulin receptor signalling 
suppresses glucose release from liver

Question 28

first line treatment for type 1 diabetes and 3 types

Answer 28

insulin

animal (porcine/bovine), human analogue and human