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GASTROINTESTINAL PHYSIOLOGY

Appetite and Hunger

Smell I Vcntomcdial hypothalami

.offood ¹ ............ *

(inhibitory: Sjticly utfiterT

I Ijlcral hypollialamk JW.1

| (fadlHative: ^appolite center'

Touch

(sucking

reflex)

Memory and/or untasy'"

Geniculate

bodies

(scbematic)

Taste of food

Chorda tympanl -

■ Oorsal nurlfus of vagus

■ Nudeus of solilary iract

Hearing (sounds of

food preparation,

cali to dinner, _    ,,

beli elc I    DecTeased k*vds

'    of COC CLP-1.

Thoracic

sympathetłC

ganglionic

chain

Dorsal roi ganglion

ł ^ .    and leptin

Depletion of body nutrient Stores

Myenteiic 1 and

submucous

Modę of

induting

hunger

contractions

unknown

Thoracic

splanchnic

.nerves

’NS connections)

Celiac

Hunger contractions in stornach ganglion

Figurę 7.10 Appetite and Hunger_

The sensations of hunger and satiety are complex and include multi-ple neural pathways, as well as drculating hormones. Depicted here are pathways involvcd in the sensation of hunger. Although our understanding is incomplele, the hypothalamus is known to play a critical role in controlling appetite and food intake. When food is ingested, chołecystokinin and GLP-1 (glucagon-like peptide) are released from neuroendocrine cells in the intesline. These hormones suppress appetite and give the sensation of satiety. In the absence o-food, the levels of these hormones are Iow. Long-term regulation of food intake may involve the hormone leptin, which is produced by fat cells. When lat Stores are high, leptin is released and thought to act on the hypothalamus to suppress appetite. When body nutrient Stores are depleted, leptin levels are Iow.

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