Diabetes metabolism basics

Question 1

what is the process called by which insulin attaches to cell receptors

Answer 1

signal transduction

Question 2

what are fat, glycogen and protein all broken down into that enters the krebs cycle

Answer 2

acetyl co-a

Question 3

what are ketones formed from

Answer 3

acetyl co-a

Question 4

what cells produce glucagon, insulin, somatostatin and pancreatic polypeptide and %

Answer 4

alpha-11%
beta-85%
delta-3%
pp cells or f cells-1%

Question 5

steps of insulin production

Answer 5

1. preproinsulin made in er
2. then cleaved to proinsulin
3. proinsulin transported to golgi a
4. prohormone convertase enzymes splits c-peptide from insulin and carboxypeptidase enzyme removes dipeptide residues
5. insulin and c-peptide secreted

Question 6

what is the biphasic response of insulin

Answer 6

in response to food
-stored insulin is released first
followed by newly synthesised insulin

Question 7

what affects insulin secretion

Answer 7

• blood glucose concentration
• prescence of food in gut
• symp and parasymp

Question 8

what is the incretin effect and which hormone

Answer 8

prescence of food and release of gut hormones GLP-1 from L cells that stimulate insulin
Also GIP

Question 9

primary genes in insulin secretion 2

Answer 9

HNF

glucokinase

Question 10

effect of glucose on cells

Answer 10

1. glucose passes through cell membrane GLUTs transporters on beta cells
2. glucose converted to g6p by glucokinase
3. g6p can be made to acetyl co-a and go into krebs cycle to make atp

Question 11

how does high glucose in blood increase insulin secretion

Answer 11

1. glucose in krebs cycle makes atp in beta cells
2. high atp level closes the potassium channel in cell membrane
3. depolarises the cell which opens calcium channels
4. increased intracellular calcium causes exocytosis of insulin granules

Question 12

where does insulin act first

Answer 12

at the liver to promote glycogen synthesis glycogenesis

Question 13

is insulin anabolic or catabolic

Answer 13

anabolic it builds

Question 14

normal daily insulin secretion

Answer 14

0.7-0.9 per kg

Question 15

what insulin does

Answer 15

• stimulate lipogenesis
• inhibit lipolysis
• stimulate glycogenesis
• inhibit glycogenolysis
• inhibit ketogenesis
• inhibit hepatic gluconeogenesis
• stimulate glucose uptake by cell
• stimulate protein synthesis and inhibit degradation

Question 16

where is glut 1, glut4, glut2 and glut 3 found and are they insulin dependent

Answer 16

glut1=brain not
glut 4- muscles= not during exercise
glut 4=fat,adipose insulin dependent
glut 2=liver, pancreas and si= not 
glut 3= brain,neuron and sperm= not insulin depndent

Question 17

which one of glut 2 and glut 3 has a high capacity for glucose but a low affinity

Answer 17

glut 2

ie when glucose is in the hepatocytes then insulin stimulates it but not insulin dependent ie glucose dependent

Question 18

skin sign of diabetes

Answer 18

acanthosis nigricans= dark patches of skin often under axilla

Question 19

hba1c measures what

Answer 19

glucose on erythrocytes or rbc

Question 20

how long do rbc live

Answer 20

120 days so gives 3 months estimate

Question 21

conditions that can affect hba1c

Answer 21

• where rbc survival is reduced eg anaemia, splenomegaly, antiretroviral drugs
• renal dialysis
• iron and b12 deficiency

Question 22

what tests can be used to detect diabetes other than glucose

Answer 22

• islet autoantibodies in 1dm eg GAD, IA2, ZNT8
• c-peptide
• urine protein

Question 23

what can fats not be converted into

Answer 23

glucose