regulation of energy balance Flashcards
which GI diseases can cause spontaneous weight loss
- chronic pancreatitis - CF - IBD - parasitic infection
what other than gene mutations can lead to obesity
epigenetics - early exposure to high energy diet –> epigenetic changes in genes controlling hunger
what is the association between food and energy expenditure
in a normal person - people will increase E expenditure in an effort to prevent weight gain and vice versa
how is leptin transported into the brain
by a receptor on the choroid plexus
how the double labeled water method of measuring energy expenditure work
label the body water with stable isotopes of oxygen and hydrogen. - O2-18 is lost from the body in the form of water and CO2 - 2H is lost only as water - difference between them reflects the CO2 production (result of fat, carbohydrate and protein oxidation)
what determines how much leptin is made
the size of the adipocytes - bigger cell - more leptin
what is the split up of energy expenditure by the body?
- most basal (65-75%)
- Thermogenesis (15-20%)
- activity (10-15%)
primary NTs produced in the arcuate nucleus for hunger/satiety and what does each one specifically do?
NPY - cause you to eat AGRP - cause you to eat CART - inhibits food intake alpha-MSH - inhibits food intake
if you lack orrexin gene what happens
narcolepsy
what is the most common association of leptin and obesity
most people who are obese are resistant to leptin signals due to a SNP in the receptor
why does glucose and other nutrients inhibit hunger
- increases LCFA-CoA which inhibits food intake
which main infections can cause spontaneous weight loss
- TB - subacute bacterial endocarditis - amoebic abscess - HIV
which malignancies commonly cause spontaneous weight loss
- bowel - pancreas - liver - lymphoma - leukaemia
if all things equal…. if the amount of leptin increases.. what happens to hunger
reduces
what are the NTs produced in the paraventricular nucleus for hunger/satiety and what are their functions?
oxytocin CRH both stimulate food intake
which areas of the hypothalamus interact
arcuate nucleus Paraventricular hypothalamic nucleus laternal hypothalamus
what peripheral signals does the hunger centre of the brain respond to?
size of fat stores presence of food int he gut
why does a diabetic not respond to leptin injection to stop eating
has a mutation in the R for leptin
what causes obesity
energy in>energy out - only in the weight gain phase
why do some people put on weight when over fed and others dont?
due to change in energy expenditure - those who put on weight didnt change their activity thermogenesis - those who didnt put on weight have a big change in activity thermogenesis (fidgiting)
where is leptin synthesised
adipocytes
function of leptin
signals the size of the fat stores in the body
common mutations causing human obesity
- leptin gene - leptin gene R - MSH gene signalling
what is the name of the equations used to predict energy expenditure
Harris-Benedit equations
