13.
Bolus is the food swallowed at one time
Epiglottis blocks windpipe, prevents choking
14.
Long tube
Connects pharynx to
the stomach
Peristalsis, muscle
contraction
Lower esophageal
sphincter
Heartburn
15.
Lower esophageal sphincter and pyloric sphincter
control entry and exit from stomach
Storage capacity of ~4 cups
Secretion of hydrochloric acid, enzymes, including
a protease, gastric lipase; mucus, the hormone
gastrin, and intrinsic factor (B12)
Stomach secretes about 2000-2500 ml of gastric
juice daily
16.
pH of stomach is low, 1 to 4; kills many
bacteria and micro-organisms
Achlorhydria, gastrectomy, GI dysfunction or
disease ↑ risk of bacterial overgrowth in the
intestines
17.
Protein digestion begins with pepsinogen
which is converted to active pepsin in acidic
stomach environment
Chief cells secrete acid-stable gastric lipase,
which has minor effect on shorter-chain
triglycerides
18.
Most of a liquid meal exits in 1 to 2 hours
and most of a solid meal in 2 to 3 hours
Formation of chyme
Mucus layer protects stomach from digestion
Very little absorption of nutrients
21.
Most digestion and absorption happens
here
About 5-7 meters
Duodenum (.5 meters)
Jejunum (2-3 meters)
Ileum (3-4 meters)
22.
Folded walls with villi projections
Absorptive cells are located on the villi
Increases intestinal surface area 600x
Rapid cell turnover
23.
24.
25.
Passive diffusion: driven by concentration;
fats, water, some minerals
Active absorption: uses energy; glucose and
amino acids
Phagocytosis and pinocytosis: absorptive cells
engulf compounds, generally larger
molecules, as in immune substances in
breast milk
26.
27.
28. Digestion → small particles
End products of digestion:
Carbohydrates → monosaccharides
Proteins → amino acids
Fats → glycerol, fatty acids
29. Through small intestine walls
Absorbed into
Blood – water soluble nutrients
Lymph – fat soluble nutrients
Blood → liver → general circulation
Liver detoxifies and repackages
30.
~3 1/2 feet in length
No villi or enzymes present
Little digestion occurs
Absorption of water, some minerals, vitamins
Bacteria break down fiber; produce Vitamin K
Formation of feces for elimination
35.
Produces glucagon and insulin (endocrine)
Manufactures digestive enzymes→ small
intestine
Secretes pancreatic juices
Bicarbonate needed to neutralize chyme
when it enters small intestine
47.
92% to 97% of the diet is absorbed
Small intestine—key role in digestion and
absorption
Intestines: 7 meters long
—Villi and microvilli/brush border
49.
GI tract compromised after starvation
Feeding results in cellular proliferation,
which restores normal gastrointestinal
architecture and function after a few days
50.
The major portion of fat digestion takes
place in the small intestine as a result of
pancreatic lipase
59.
Released from gastric mucosa and
duodenum in presence of peptides and
amino acids; stimulates secretion of
hydrochloric acid and pepsinogen; increases
gastric antral motility, increases LES tone
60.
Secretin: from duodenal mucosa in presence
of acid in small intestine; stimulates
pancreas to secrete water and bicarb; also
insulin and pancreatic enzymes
61.
Released from proximal small bowel in
presence of peptices, amino acids, fat, HCL,
stimulates pancreas to release pancreatic
enzymes
62.
Released from small intestine in presence of
glucose and fat; inhibits gastrin-stimulated
release of gastric acid
63.
Released from stomach and small and large
intestine in presence of biliary and
pancreatic secretions; promotes gastric
emptying and increases GI motility
64.
Released from stomach, pancreas, and
upper small intestine in presence of acidity
and products of protein and fat digestion;
inhibits release of gastrin, motilin, and
pancreatic secretions; decreases motility of
GI tract
65.
It’s important to know the physiology and
function of the GI tract in order to understand
the implications of pathophysiology
