Apetite Regulation Flashcards
Define apetite
Desire to eat food
Define hunger
Need for eating
Define anorexia
Lack of apetite
Define satiety
Feeling of fullness - disappearance of appetite after a meal
Define BMI
kg/height^2
BMI for underweight
<18.5
Normal BMI
18.5-24.9
Overweight BMI
25.0-29.9
BMI for obese
30.0-39.9
BMI for morbidly obese
> 40
What are the risks of obesity
- Type II diabetes
- Hypertension
- CAD
- Stroke
- Osteoarthritis
- Obstructive sleep apnoea
- Carcinoma
What type of fat deposition is a greater risk for obesity
Visceral fat than subcutaneous fat
Where is the lowest proportion of working-age people who are obese in the UK
London
What does weight regulation depend on
Environment
Genes
What is a risk with high levels of cortisol if you have sleep deprivation
High risk of diabetes / obesity
How does sleep deprivation effect Leptin levels
Decreases it (we get hungry)
What three structures effect appetite regulation
- Adipose tissues
- Brain
- GI Tract
Why do we eat?
- Physiological drive (leptin levels)
2. External stimuli (presence of food)
What is the sensory stimuli to food
- Expectations
- Associations
- Recognition of food
How does is the quantity of food we eat limited
- Stretch of the stomach causes receptors to be activated and Ghrelin levels fall
What type of food prolongs satiety
Protein
How does high fat effect satiety levels
Stimulates and entices people to eat more
Where is the hunger centre located in the brain
Lateral hypothalamus
What nucleus in the hypothalamus regulates satiety
Ventromedial hypothalamic nucleus
What 3 Hormones effect appetite
Leptin
Insulin
Cortisol
How does NPY and AgRP effect hunger
Increases it
How does POMC effect appetite
Decreases it
What stimulates the production of POMC and CART
Leptin as it binds to the arcuate nucleus
What nucleus produces POMC
Arcuate nucleus
Why does the arcuate nucleus have a fenestrated BBB
So that we can sample the peripheral hormones
Where is leptin expressed
White fat
What type of receptor is leptin
Cytokine
Where is leptin receptor found
Hypothalamus
What happens to leptin levels after a meal
They increase
How does Leptin effect NYP and AgRP levels
Inhibits them
How many AA are in peptide YY
36
What molecule is peptide YY similar to
NPY
What does Peptide YY bind to
NPY
What secretes Peptide YY
Neuroendocrine cells in the Ileum, pancreas and colon
Role of peptide YY
Inhibits gastric motility + reduces appetite
Where are receptors for CCK found
Pyloric sphincter
Role of CCk
Delays gastric emptying
Gall bladder contraction
Insulin release
Controls satiety via vagus
Number of AA in Ghrelin
28
Where is Ghrelin expressed
Stomach
Role of Ghrelin
Stimulates GH release
And increases appetite
How does gastric bypass surgery effect Ghrelin levels
It lowers
What is POMC
A chain of different amino acids that can be cleaved into smaller molecules to control hunger
What can POMC be broken down into
ACTH (which in turn can be broken down into alpha-MSH and CLIP)
Beta LPH
Role of melanocortin peptides
Signalling of satiety to the brain
Symptoms of POMC deficiency
- Severe obesity at early age due to low ACTH
- Red hair
- Pale skin that easily burns when exposed to the sun
Not enough alpha-MSH and beta-MSH dysregulates body energy balance leading to over-eating
Hat does Leptin and insulin stimulate
POMC/CART
What does Leptin and insulin inhibit
NPY/AgRP
How does POMC/CART effect alpha-MSH levels
Increases them
Where is alpha-MSH produced
Pars intermedia of pituitary gland
Role of alpha-MSH
Production of melanin
Surpasses appetite
Sexual arousal
How common is monogenetic obesity
Rare
Where is the pituitary gland located
Pituitary fossa just below the OPTIC CHIASM
What lies between the pituitary glands
Two cavernous sinuses
What is the anterior pituitary gland sometimes called
Adenophysis
What is the posterior pituitary gland sometimes called
Neurohypophysis
Blood supply from the anterior pituitary gland
Superior hypophyseal artery
How many hormones are produced by the anterior pituitary gland
6
