Obestity - 111 Flashcards
What are the 3 important subregions of the hypothalamus regarding obesity?
Ventromedial
Lateral
Arcuate nucleus
What is the BMI that defines someone as obese?
> 30kg/m2
What subregions of the hypothalamus are directly sensitive to blood glucose levels?
Lateral and ventromedial
When is the ventromedial hypothalamus turned on?
When there is an increase in blood glucose. It causes satiety
When is the lateral hypothalamus turned on?
When there is a decrease in blood glucose. Causes hunger
What are anorexigenic peptides? Give 2 examples and state where they are produced and what they do
They are produced by the arcuate nucleus in response to high leptin levels and act to inhibit feeding behaviour. Examples include CART and alpha MSH.
What are orexigenic peptides? Where are they produced and what do they do?
Produced by arcuate nucleus in response to low leptin levels. They stimulate feeding. Examples are AgRP and NPY.
What receptor do AgRP and alpha MSH bind to? What effects do they have?
Melanocortin receptor (MCR4).
AgRP blocks it.
alpha MSH activates it.
What is the most common cause of inherited obesity?
MCR4 mutations
When is insulin produced? What effect does it have?
In response to an increase in blood glucose.
An infusion of insulin into the brain decreases feeding - reacts on hypothalamus to release anorexigenic peptides (CART etc)
What fuel type does the brain depend on normally and in starvation?
Normally - glucose.
In starvation - ketone bodies
Name some tissues that depend on glucose as their fuel source
RBCs, the brain, skeletal muscle (in severe exercise) and lymphocytes
Name some tissues that depend on fatty acids as their fuel type?
Liver, cortex of kidney, cardiac muscle, skeletal muscle (NOT in severe exercise)
Name some tissues that depend on ketone bodies as their fuel type
Cardiac muscle, cortex of kidney, brain (in starvation), skeletal muscle.
Where are fatty acids oxidised to ketone bodies?
In the liver. Ketone bodies are more soluble in the blood stream
