Hypothalamic control of Eating Flashcards
What are the the 2 basic preabsorptive satiety factors (short-term signals)?
- gastric distension
- nutrients in intestine
What are the oropharyngeal satiefy factors?
related to taste and smell
if the animal is fasted - they will increase appetite
if the animal is fed - they will decrease appetite
What is the signalling pathway for gastric distention?
- food enters stomach, causing it to stretch
- mechanoreceptors activated
- signal sent via vagal afferents
- synapse on the nucleus tracus solitarius in medulla
- this decreases food intake
What hormone is made in the duodenum in response to fatty meals?
colecystokinin (CCK)
What are the 3 effects of CCK?
- gallbladder contraction
- pyloric constriction
- increased gastric contractions
What is the signalling pathway for CCK?
CCK secretion
CCk activates CCK receptors
increased signalling form vagal afferents
increased signalling in the NTS
decrease in food intake
What hormone causes an INCREASE in appetite?
ghrelin
Where is ghrelin made? When?
Made in the stomach during fasting
What are the symptoms of Prader-Willi syndrome and how does this tie into our hunger discussion?
- fetal hypotonia
- mentlal retardation
- hypogonadotropic hypogonadism
- obesity
- hyperphagia
they have excessive eating habits because they have excessive ghrelin secretion
What is the controlled variable in long-term signals of satiety?
fat stores controlled by “adiposity” signals
What hormone is released from adipocytes to decrease food intake?
leptin
Where are the sites of action for leptin?
brain stem and hypothalamus
What was the effect of NTS response to gastric stretch in the presence of leptin?
leptin made the NTS more responsive to stretch
Lesions of the lateral hypothalamic area will result in what?
aphagia due to damage to the medial forebrain bundle
- you have reduced motivation to eat
- you can potentiallh have reduced motor function
- loss of neurons that synthesize Orexin, which is an orexigenic peptide that makes us eat more
What happens with stimulation of the lateral hypothalamic area?
you get an increase in orexin in the brainstem, which makes you eat more/grow
What affect do the paraventricular nucleus neurons have on food intake? How?
They decrease food intake by releasing “catabolic” neurotransmitters int he brain - corticoropin releasing hormone
What are the two populations of neurons within the arcuiate nucelus?
neuropeptide Y neurons
melanocortin (POMC-derived) neurons
Fill in the blank:
Neuropeptide Y neurons project to both the PVN and LHA to ____ food intake
Melanocortin neurons project ot he PVNa nd LHA to ____ food intake
increase
decrease
Leptin ____ NPY neurons and _____ melanocortin neurons to _____ food intake
inhibits the NPY
activates the melanocortin
decreases food intake
What affect does ghrelin have on the ARC?
it activates NPY neurons to increase eating
How does the NST reduce food intake?
it inhibits various cranial nerve nuclei involved in eating
so trigeminal motor
vagus dorsal motor
hypoglossal
nucleu ambigus
