Regulation of Energy Intake & Body Weight Regulation Flashcards Preview

DEMS: Unit IIb > Regulation of Energy Intake & Body Weight Regulation > Flashcards

Flashcards in Regulation of Energy Intake & Body Weight Regulation Deck (19)
Loading flashcards...
1

Role of hypothalamus in regulation of energy balance and body weight regulation

  • Hypothalamus involved in both control of short- and long-term regulation of body weight
  • PVN, VMN, Arc, LH regulate food intake/disposition
    • Process information concerning peripheral energy stores
    • Then stimulate or inhibit feeding/alter gastric motility and food metabolism/utilization

2

Role of ventromedial nucleus (VMN) in regulation of energy balance and body weight 

  • Inhibitory (-)
  • "Satiety center"
  • If your ventral (tummy) region is full --> stop eating
  • Stimulation of this region results in cessation of eating even in hungry animals

3

Role of lateral hypothalamus in regulation of energy balance and body weight

  • Stimulatory (+)
  • Causes voracious eating via melanin-concentrating hormone (MCH) and orexins (hypocretins)
  • If your lateral region is skinny, keep eating

4

Role of arcuate nucleus (Arc) in regulation of energy balance and body weight

  • Inhibitory and stimulatory (+/-)
  • Activation can produce hunger via NPY/AgRP
  • Also can produce satiety via a-MSH/POMC-CART

5

Mechanisms used by hypothalamus to promote/inhibit food intake

  • Regulating food intake (hunger/satiety)
  • Altering gastric motility
  • Altering food metabolism/utilization
  • Neurons in LH support behaviors like chewing, licking, swallowing (via cranial nerves)

6

Impact of knocking out the POMC gene

  • Also knocks out a-MSH
  • Increase body weight

7

Impact of knocking out NPY gene

  • Decrease weight

8

Impact of loss-of-function mutation in melanocortin receptor (MCR)

  • Increase weight

9

Peripheral hormones derived from GI tract (4)

  • Ghrelin (stomach)
  • CCK (duodenum)
  • PYY (distal ileum)
  • GLP-1 (distal ileum)

10

Role of ghrelin in regulating food intake/body weight

  • Stimulatory (+)
  • Makes your tummy growl, peaks prior to a meal
    • Ghrelin = growlin' 
  • Stimulates NPY/AgRP neurons
  • Works opposite to leptin and insulin
  • Increases food intake

11

Role of CCK in regulating food intake/body weight

  • Inhibitory (-)
  • Senses food
  • Activates vagal afferents in peritoneum and area postrema

12

Role of PYY in regulating food intake/body weight

  • Inhibitory (-)
  • Anorexic effect via inhibition of hypothalamic NPY/AgRP neurons
  • Decreases food intake

13

Role of GLP-1 in regulating food intake/body weight

  • Inhibitory (-)
  • Incretin hormone
  • Acts on area postrema via NTS
  • Reduces food intake

14

Peripheral hormone released from the pancreas & its role in regulating food intake/body weight

  • Insulin! (durrr)
  • Inhibitory (-)
  • Works like leptin
  • Levels parallel body fat content
  • Receptors in hypothalamus and brainstem

15

Peripheral hormone released from adipose tissue & its role in regulating food intake/body weight

  • Leptin
  • Inhibitory (-)
  • "Satiety hormone" 
  • Receptors in arcuate nucleus and VMN
  • Inhibits NPY/AgRP
  • Activates a-MSH/CART
    • Found by mouse model --> knockouts are hugely obese
    • Not the silver bullet of obesity cure

16

Role of brain reward pathways & environmental cues in development of obesity

  • Food is rewarding
  • We override homeostatic signals to stop us from eating --> get fat
  • Taste info goes through NTS to hypothalamus, thalamus, amygdala, forntal cortex
  • Affects areas of feeding & satiety PLUS motivation & reward
  • Nucleus accumbens and dopamine afferents involved in drug addiction PLUS induction of feeding
  • Serotonin also impacts feeding (phen/fen used as obesity tx)
    • SSRI activates a-MSH/CART neurons --> decrease food intake
  • Eating is cognitive/executive decision
  • Affected by social/environmental cues, depression, anxiety

17

Internal inputs to food intake behavior

  • Reward mechanisms
  • Cravings
  • Thinking about food (you are now, aren't you?)
  • Restraint - can you ignore a delicious cookie? (nope)
  • Learned behaviors - how did you learn to eat? 
  • Attention

18

External inputs to food intake behavior

  • Environmental cues
    • Sight
    • Smell
    • Taste
  • Availability and portions
  • Social context
  • Time cues

19

Simplified "cause" of obesity

  • Non-homeostatic regulation (internal and external inputs) overrules homeostatic physiologic regulation of energy intake