3
Nutrient Absorption
GI Hormone Regulation of Caloric Balance, Food Digestion,
and Nutrient Utilization
Stomach
(~1 foot)
• Water
• Alcohol
• Fatty acids
• Amino acids
• Minerals (e.g., calcium
during calcium
def iciency, iron)
• Some vitamins
• Bile salts
• Bile acids
• Vitamin B12
• Some vitamins
• Some minerals
• Water
• Sodium chloride
• Potassium
• Intestinally derived
vitamin K
Duodenum
(~1 foot)
Ileum
(~12 foot)
Large intestine
(~5 foot)
Before eating
(during fasting):
GI hormones may
increase hunger
• Ghrelin
• NPY
a
Common gastrointestinal hormone actions in
response to eating
Hunger
a
The biologically active PYY and PP are expressed by endocrine cells in the
digestive system. Animal studies suggest NPY endocrine cells are found
throughout the small and large intestine, with NPY thus being involved in both
gut-brain and brain-gut axis (bidirectional signaling). NPY is mainly described
as a highly abundant orexigenic peptide found throughout the brain.
Digestion
• Delayed gastric emptying
• Digestive enzyme release
• Post absorptive nutrient
metabolism
Jejunum
(~8 foot)
The jejunum absorbs
the greatest amount of:
• Simple sugars
• Fatty acids
• Proteins
• Minerals
• Vitamins
