Insulin regulation and obesity

Question 1

What is insulin initially synthesised as?

Answer 1

It is initially synthesised as preproinsulin

Question 2

How do you get from preproinsulin to insulin?

Answer 2

signal peptide is removed to leave proinsulin
C-peptide is then removed to leave insulin

Question 3

What is insulin released in response to?

Answer 3

• Dietary elements
• primarily glucose
• possible also aminoacids
• diet induced intestinal hormones (GLP-1, GIP)

Question 4

Why do oral sugars provoke a bigger insulin secretion than iv sugars?

Answer 4

• Due to the incretin secretion from the intestine
• this can then stimulate beta cells

Question 5

What are the two main incretins?

Answer 5

• Gastric Inhibitory Polypeptide
• Glucagon-Like Peptide-1

Question 6

What is an insulin sensitive tissue and name three of them

Answer 6

• a tissue that requires insulin to take up glucose
• liver, fat and resting muscle
• the glucose enters via GLUT-4 receptors

Question 7

What is an insulin-insensitive tissue?

Answer 7

• takes up glucose on a simple concentration gradient
• usually any other tissue e.g brain, kidney, intestine, exercising muscles
• glucose enters the cell via GLUT-2 receptors

Question 8

Name 5 effects that insulin has on the body

Answer 8

1. Increases cellular potassium uptake
2. Increases renal sodium resorption
3. Stimulates gastric acid secretion
4. Vascular effects- NO for vasodilation, Endothelin for Vasoconstriction
5. Cellular mitosis, Growth and Differentiation

Question 9

What is the definition of insulin dysregulation?

Answer 9

a disturbance of the balanced inter-relationship between plasma concentrations of insulin, glucose and lipids

Question 10

What are the two main effects of insulin dysregulation?

Answer 10

• Facilitates glycogen breakdown
• Stimulates gluconeogenesis
• Facilitates fat mobilisation

Overall conserves glucose for vital organs

survival advantage under harsh conditions

Question 11

What is gynoid adiposity?

Answer 11

Fat in the hips/ legs

Question 12

What is android adiposity?

Answer 12

Fat in the abdominal area

Question 13

What are the three main ways of measuring obesity in a laboratory?

Answer 13

• Bioimpedence
• Hydrometry
• Tissue imaging

Question 14

What chemical does hydrometry use?

Answer 14

Deuterium Oxide (D2O)

Question 15

What is the metabolic effect of insulin on carbohydrates?

Answer 15

• Stimulates glycogen synthesis
• inhibits glycogenolysis

Question 16

What is the metabolic effect of insulin on triglycerides?

Answer 16

• Stimulates fatty acid uptake and triglyceride synthesis
• inhibits lipolysis

also inhibits gluconeogenesis

Question 17

What is the metabolic effect of insulin on protein?

Answer 17

• Stimulates cellular amino acid uptake
• inhibits proteolysis

Question 18

What are some factors that cause insulin dysregulation?

Answer 18

• Genetics
• Obesity
• Exercise/ Fitness
• Diet
• Other hormones

Question 19

What is the advantage of insulin dysregulation?

Answer 19

• Conserves glucose for vital organs
• Mobilises energy stores

offers a survival advantage under harsh conditions

Question 20

What is regional obesity?

Answer 20

• Fat in the omentum
• retroperitoneal
• mesocolon
• nuchal ligament
• tail-head

Question 21

What may release of adipkines cause?

Answer 21

• Cardiovascular disease
• Cerebrovascular disease
• Kidney disease
• Retinal disease
• Arthritis
• Asthma
• Cancer

Question 22

How does bioimpedence work?

Answer 22

lean tissue is a good conductor
Fat is a poor conductor

Question 23

What is the calculation you would do for hydrometry?

Answer 23

Total body water = dose administered/ concentration

Question 24

What calculation would you do for body fat percentage?

Answer 24

100- (TBW%/0.732)

Question 25

What is the effect of insulin dysregulation on modern lifestyle?

Answer 25

Goes from a beneficial temporary physiological status to a harmful pathological status with progressive obesity