Feeding and satiety Flashcards
what is the “normal” BMI range
18.5-24.9
what is the “underweight” BMI range
<18.5
what is the “overweightl” BMI range
25-29.9
what is the “obese” BMI range
30-39.9
what is the “morbidly obese” BMI range
> 40
how is BMI calculated
weight in kg / (height in m) squared
functions of fat (3)
energy storage
prevention of starvation
energy buffer during illness
how does the CNS influence body weight (3)
behaviour = feeding & physical activity
ANS activity = regulates angry expenditure
neuroendocrine system = secretion of hormones
where is the site of integration of feeding behaviour
the brain, hypothalamus
injuring the LATERAL hypothalamus causes what
leanness
remember = Lateral and Leanness
injuring the VENTROMEDIAL hypothalamus causes what
obesity
what is satiation
sensation of fullness generated by a meal
what is satiety
period of time between termination of one meal and the initiation of another
what is adiposity
the state of being obese
what do satiation signals do during a meal why?
increase, limit meal size
list examples of satiation signals (5)
Oxyntomodulin (OXM) Obestatin cholecystokinin (CCK) Peptide YY (PYY3-36) Glucagon-like peptide 1 (GLP-1)
where is cholecystokinin (CCK) secreted from
enteroendocrine cells in the duodenum and jejunum
what does cholecystokinin (CCK) do
signals via sensory nerves to the hindbrain and stimulates it
when is cholecystokinin (CCK) released
released in proportion to lipids and portions in meal
where is Peptide YY (PYY3-36) secreted from
endocrine mucosal L-cells of the GI tract
what does Peptide YY (PYY3-36) do?
inhibits gastric motility, slows emptying, and reduces food intake
when is Peptide YY (PYY3-36) released
post meal
where is Oxyntomodulin (OXM) released from
oxyntic cells of the small intestine
what does Oxyntomodulin (OXM) do
acts to suppress appetite (mechanism unknown)
when is Oxyntomodulin (OXM)
released
post meal
where is Obestatin released from
cells lining stomach and small intestine
what does Obestatin do
reduces food intake (mechanism unknown)
example of a hunger signal
ghrelin
where is ghrelin released from
oxyntic cells in stomach
what does ghrelin do
stimulates food intake
when is ghrelin released
levels increased before meals
which two hormones act on hypothalamic neurones (aka “adiposity” signals)
leptin
insulin
what do leptin and insulin report to the hypothalamus
fat status
where is leptin made and released from
fat cells
where is insulin made and released from
pancreatic cells
why does obesity result in leptin resistance (2 theories)
- defective leptin transport to brain
2. altered signal transduction following leptin binding to its receptor
give an example of a drug treatment for obesity
orlistat
what is the mechanism of action of orlistat
inhibits pancreatic lipase which decreases triglyercide absorption
side effects of orlistat
cramping
severe diarrhoea
what must be co-prescribed with orlistat
vitamin supplements
what is the preferred therapy for obesity
bariatric surgery (aka gastric by-pass surgery)
what is the method of action of orlistat
lipase inhibitor
