Sugar, Sex And Satiety Flashcards
Above what BMI is a person considered obese?
30
What do orexigenic signals do
Lowers energy expenditure
Lowers satiety
Increases food intake
Increases lipogenesis
Describe neuropeptide Y.
Orexigenic signal released into the paraventricular nucleus of the hypothalamus
Describe agouti-related peptide
Orexigenic signal released into the paraventricular nucleus of the hypothalamus
Describe 5HT (satiety)
Anorexigenic peptide released into the paraventricular nucleus of the hypothalamus
Where is leptin produced?
Adipose tissue
Where are leptin receptors found?
Satiety centre of the hypothalamus
Is leptin orexigenic or anorexigenic?
Anorexigenic
What do ob/ob mice lack?
Leptin genes
What do db/db mice lack?
Genes for leptin receptors
Which drug inhibits energy uptake?
Phentermine
What drug inhibits fat absorption?
Orlistat
What drug enhances energy expenditure?
Orlistat
What are the strategies employed to treat obesity?
Inhibit energy uptake
Inhibit fat absorption
Enhance energy expenditure
Fat mobilisation stimulation
How does insulin affect leptin activity?
Stimulates insulin release, therefore increases leptin activity
How do glucocorticoids affect leptin activity?
Glucocorticoids antagonise leptin and insulin, decreasing leptin activity
Where is insulin synthesised and released from?
Beta cells in the islet of langherans of the pancreas
What signals the release of insulin?
An increase in glucose conc.
Rate of change of glucose conc.
Arg, Leu, ketones, gastrin; secretin
Describe phase one insulin release.
Glucose enters beta cell via GLUT2 transporter.
Glucose is converted to ATP
ATP blocks the K channel reducing the efflux of K
the cell depolarises causing an influx of Ca
Ca causes exocytosis of insulin granules
What effects does insulin have on the liver?
Increases glycogenogenesis
Reduces glycogenolysis
Increases glycolysis
Reduces glucoenogenesis
What effect does insulin have on muscle?
Increases amino acid uptake and synthesis
Increases glucose uptake
Increases glycolysis
Increases glycogenogenesis
What effect does glucose have on adipose tissue?
Increased lipogenesis
Reduced lipolysis
Increases triglyceride formation
How does the insulin receptor initiate intracellular signalling?
Insulin binds to extracellular alpha subunit
Binding causes the beta subunits to cross-autophosphorylate
Name three signalling pathways engaged through insulin receptor activation.
IRS-1: link between receptor and other signalling proteins
PLC: catalyses the activation of serine/threonine phosphatase
GLUT4: recruites GLUT4 transporters to the membrane to increase glucose uptake
What pathologies does uncontrolled glycaemia produce?
Neuropathy
Coma
Nephropathy
Myocardial infarction
What is the pathophysiology of IDDM?
Autoimmune response of HLA antigens attacking beta cells
0-10% cell function
What is the pathophysiology of NIDDM?
Reduced insulin levels
Target tissues are resistant to insulin
What is the pharmacokinetic strategy with insulin injections?
Increase ligand concentration to increase receptor activation
How do sulphonylureas work?
Block K channels of beta cells
Beta cells depolarise
Voltage sensitive ion channels open
Calcium entry into cell stimulates insulin release
How do biguanides work?
Inhibit fatty acid break down
Inhibit glucose uptake from gut
Inhibit gluconeogenesis and glycogenolysis in the liver
Increase tissue sensitivity to insulin
How do thiazolenediones work?
Activate PPAR- gamma receptors
Sensetise peripheral tissues to insulin
What does GnRH liberate from the anterior pituitary?
FSH and LH
What are the principal activities of FSH?
Stimulates follicle development
Stimulates oestrogen production in follicle
Increases receptor expression in follicle
Stimulates Sertoli cells to nourish sperm
What are the principal activities of LH?
Stimulates androgen synthesis in follicle
Stimulates follicle development and rupture
Involved in the conversion of the ruptured follicle to the corpus luteum
Stimulates testosterone production
What is the gonadotropin released by the zygote and placenta?
LGC
What two steroids are the principal female sex hormones?
Oestrogen and progesterone
What is COC?
Ethinyloestradiol and norgestrel
Pill taken for 21 days
7 drug free days
What is POP?
Levonorgestrel
Taken continuously
What is the standard HRT?
Ethinyloestradiol and norgestrel
What is the post-hysterectomy HRT?
Ratoxifene
Drugs used to treat infertility.
Clomiphene
Drugs used to treat endometriosis
Danazol
How is the BMI calculated?
Weight/(height) squared
