Insulin regulation and obesity Flashcards
What is insulin initially synthesised as?
It is initially synthesised as preproinsulin
How do you get from preproinsulin to insulin?
signal peptide is removed to leave proinsulin
C-peptide is then removed to leave insulin
What is insulin released in response to?
- Dietary elements
- primarily glucose
- possible also aminoacids
- diet induced intestinal hormones (GLP-1, GIP)
Why do oral sugars provoke a bigger insulin secretion than iv sugars?
- Due to the incretin secretion from the intestine
- this can then stimulate beta cells
What are the two main incretins?
- Gastric Inhibitory Polypeptide
- Glucagon-Like Peptide-1
What is an insulin sensitive tissue and name three of them
- a tissue that requires insulin to take up glucose
- liver, fat and resting muscle
- the glucose enters via GLUT-4 receptors
What is an insulin-insensitive tissue?
- 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
Name 5 effects that insulin has on the body
- Increases cellular potassium uptake
- Increases renal sodium resorption
- Stimulates gastric acid secretion
- Vascular effects- NO for vasodilation, Endothelin for Vasoconstriction
- Cellular mitosis, Growth and Differentiation
What is the definition of insulin dysregulation?
a disturbance of the balanced inter-relationship between plasma concentrations of insulin, glucose and lipids
What are the two main effects of insulin dysregulation?
- Facilitates glycogen breakdown
- Stimulates gluconeogenesis
- Facilitates fat mobilisation
Overall conserves glucose for vital organs
survival advantage under harsh conditions
What is gynoid adiposity?
Fat in the hips/ legs
What is android adiposity?
Fat in the abdominal area
What are the three main ways of measuring obesity in a laboratory?
- Bioimpedence
- Hydrometry
- Tissue imaging
What chemical does hydrometry use?
Deuterium Oxide (D2O)
What is the metabolic effect of insulin on carbohydrates?
- Stimulates glycogen synthesis
- inhibits glycogenolysis
What is the metabolic effect of insulin on triglycerides?
- Stimulates fatty acid uptake and triglyceride synthesis
- inhibits lipolysis
also inhibits gluconeogenesis
What is the metabolic effect of insulin on protein?
- Stimulates cellular amino acid uptake
- inhibits proteolysis
What are some factors that cause insulin dysregulation?
- Genetics
- Obesity
- Exercise/ Fitness
- Diet
- Other hormones
What is the advantage of insulin dysregulation?
- Conserves glucose for vital organs
- Mobilises energy stores
offers a survival advantage under harsh conditions
What is regional obesity?
- Fat in the omentum
- retroperitoneal
- mesocolon
- nuchal ligament
- tail-head
What may release of adipkines cause?
- Cardiovascular disease
- Cerebrovascular disease
- Kidney disease
- Retinal disease
- Arthritis
- Asthma
- Cancer
How does bioimpedence work?
lean tissue is a good conductor
Fat is a poor conductor
What is the calculation you would do for hydrometry?
Total body water = dose administered/ concentration
What calculation would you do for body fat percentage?
100- (TBW%/0.732)
What is the effect of insulin dysregulation on modern lifestyle?
Goes from a beneficial temporary physiological status to a harmful pathological status with progressive obesity
