Session 4 - Can't Diabeat it

Question 1

What is diabetes characterised as?

Answer 1

It is characterised as chronic hyperglycaemia due to insulin deficiency, insulin resistance or both.

Question 2

Why does glucose need to be kept in a specific range?

Answer 2

It is vital that Glucose is kept within a lower and upper range. Glucose must be kept above a minimum level to adequately support the CNS, but an excessive amount of it results in damage over time.

Question 3

What is blood glucose normally maintained at?

Answer 3

5mmol/l

Question 4

What is the normal physiological range for glucose conc in blood?

Answer 4

 Rarely stray outside the range of 4.5 – 5.6mmol/LL regardless of food, fasting or exercise

Question 5

What is the minimum blood glucose conc?

Answer 5

o Plasma glucose concentration of < 2.2mmol/L may result in hypoglycaemic coma and death due to insufficient glucose reaching the brain

Question 6

What is the maximum glucose before it begins to be excreted in urine?

Answer 6

o Plasma glucose concentration of > 10mmol/L exceeds glucose’s renal threshold, which means glucose will be present in the urine. Osmotic diuresis then occurs.

Question 7

How do the islets of langerhan detect glucose conc?

Answer 7

Glucose receptors

Question 8

What do cells in islets of langerhan secrete, and what cell do what?

Answer 8

vGlucagon (α-cells) and Insulin (β-cells)

Question 9

What factors other than glucose level can cause release of glucagon and insulin?

Answer 9

• Gastrointestinal hormones

- Autonomic Nerves

Question 10

Where can glucose receptors be found other than pancreas?

Answer 10

Ventromedial and lateral areas of hypothalamus

Question 11

What do glucose receptors in the hypothalamus do?

Answer 11

regulate appetite and feeding, and they also indirectly stimulate the release of a variety of hormones, including adrenaline, growth hormone and cortisol, all of which affect glucose metabolism.

Question 12

What tissue types do I and G target?

Answer 12

Liver, Skeletal Muscle and Adipose tissue

Question 13

Outline the structure of insulin

Answer 13

Insulin is a 51 amino acid peptide made up of an α-chain and a β-chain, linked by disulphide bonds.

Question 14

What is the half life of insulin, and what is responsible for its metabolism?

Answer 14

It has a half-life of 3-5 minutes and is metabolised to a large extent by the liver, but also by the kidneys and muscles.

Question 15

How can we detect endogenous levels of insulin?

Answer 15

Amount of C-peptide in blood, part of cleavage of insulin C-chain during post-transcription processing

Question 16

What do B cells secrete insulin in response to?

Answer 16

high blood glucose levels, as well as to glucosamine, amino acids, fatty acids, ketone bodies and Sulphonylureas.

Question 17

What 5 things inhibit insulin release?

Answer 17

low blood glucose concentration, growth hormone, glucagon, cortisol and sympathetic nervous system activation.

Question 18

What does binding of insulin to IRS on cell surface trigger

Answer 18

Activation of insulin signalling pathway, causing transporter of Glut 4 to be moved from storage vesicles to the membrane.

Question 19

Other than increased glucose uptake, what are three other effects of insulin on the cell?

Answer 19

Lipid metabolism
Protein metabolism
Growth

Question 20

What stimulates secretion of glucagon?

Answer 20

Low blood glucose conc

Question 21

What are the actions of glucagon?

Answer 21

stimulating glycogenolysis and gluconeogenesis in the liver and increasing lipolysis in adipose tissue.

Question 22

How is insulin stored?

Answer 22

-cells storage granules as a crystalline-zinc complex.

Question 23

How does insulin circulate?

Answer 23

Dissolves in the plasma and circulates as a free hormone.

Question 24

What are the three main target tissues of insulin?

Answer 24

Liver
Skeletal muscle
Adipose tissue

Question 25

Is insulin anabolic or catabolic?

Answer 25

Anabolic

Question 26

What are the short term effects of insulin?

Answer 26

Clear absorbed nutrients from the blood following a meal

Question 27

What are the long term effects of insulin?

Answer 27

effects on cell growth/cell division that relate to its ability to stimulate protein synthesis and DNA replication.

Question 28

Outline the three overarching metabolic effects of insulin

Answer 28

Carbohydrates
Lipids
Amino acid metabolism

Question 29

How does insulin effect carbohydrates?

Answer 29

• Increased glucose transport into adipose tissue/skeletal muscle
• Increased glycogenesis and decreased glycogenolysis in liver/muscle
• Decreased gluconeogenesis in liver
• Increased glycolysis in liver/adipose tissue

Question 30

How does insulin effect lipid metabolism?

Answer 30

• Decreased Lipolysis in adipose tissue
• Increased Lipogenesis and esterification of fatty acids in liver and adipose tissue
• Decreased Ketogenesis in liver
• Increased Lipoprotein lipase activity in the capillary bed of tissues such as adipose tissue

Question 31

How does insulin effect amino acid metabolism?

Answer 31

Increased Amino acid uptake and protein synthesis in liver, muscle and adipose tissue
Decreased Proteolysis in liver, skeletal muscle and adipose tissue

Question 32

Outline the 5 key characteristics of diabetes mellitus

Answer 32

o An absolute or relative insulin deficiency
 Autoimmune destruction of pancreatic β-cells
 Insulin insensitivity
o Hyperglycaemia
o Glycosuria
o Polyuria
o Polydipsia

Question 33

Why is diabetes so clinically important?

Answer 33

Associated with a whole range of macro and microvascular complications.

Question 34

What are the first steps when a patient is diagnosed with diabetes?

Answer 34

Attempt to control glucose through diet and lifestyle modifications alone.

• Lose weight by limiting fat intake whilst increasing proportionate calorie intake of complex carbohydrates keeps HBA1C levels stable.
• Reduction in alcohol, cessation of smoking and exercise will also help