The Esophagus
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Long tube
Epiglottis
Peristalsis
Lower
esophageal
sphincter
• Heartburn
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Bolus of food
Tongue
Epiglottis
Larnyx
Trachea
(a)
Esophagus
(b)
(c)
The Stomach
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Sphincters
Size
Gastric juices
Holding “tank”
Formation of chyme
Prevention of autodigestion
Physiology of the Stomach
Stomach Acid
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Destroys activity of protein
Activates digestive enzymes
Partially digests dietary protein
Assists in calcium absorption
Makes dietary minerals soluble for
absorption
Peristalsis
The Small Intestine
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Approximately 10 feet long
Folded walls
Villi
Absorptive cells
Rapid cell turnover
The Small Intestine
Nutrient Absorption
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Passive absorption
Facilitated absorption
Active absorption
Phagocytosis and pinocytosis
Nutrient Absorption
The Large Intestine
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Indigestible food stuff
No villi or enzymes
Mucus-producing cells
Absorption of water, some minerals,
vitamins
• Bacteria
– Probiotics
– Prebiotics
• Elimination
Rectum
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Stool
Elimination
Muscle contraction
Anal sphincters
Accessory Organs
• Pancreas
• Gallbladder
• Liver
The Liver
• Bile
• Gallbladder
• Enterohepatic circulation
The Pancreas
• Digestive enzymes
• Hormones
– Glucagon and insulin
• Pancreatic juices
– Bicarbonate
The Urinary System
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Kidneys
Ureter
Bladder
Urethra
Waste products
Blood acid-base
balance (pH)
Basic Renal Processes
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Nutrient Storage Capabilities
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Maintaining reserves
Adipose tissue
Glucose
Amino acids
Vitamins and minerals
– Calcium in bones
Nutrition and Genetics
• Nutrigenomics
• Nutritional diseases with a genetic link
– Cardiovascular disease
– Obesity
– Diabetes
– Cancer
Common Problems with Digestion
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Ulcers
Heartburn
Constipation
Hemorrhoids
Irritable Bowel Syndrome
Diarrhea
Gallstones
Ulcers
• Can occur in esophagus, stomach and
small intestine
• Cause
– H. Pylori
– NSAIDS
Ulcers
Heartburn
Heartburn
• Gastroesophageal reflux disease (GERD)
Constipation
• Difficult or infrequent evacuation
• Causes
– Ignoring normal urges
– Muscle spasms
– Certain medications
• Treatment
– Dietary fiber
– Fluids
– Regular physical activity
Laxatives
• Irritate the intestinal nerve
• Draw water into the intestine
• Regular use is harmful
Hemorrhoids (piles)
• Swollen veins of the rectum and anus
• Intense pressure and straining
• Dietary recommendation:
– Fiber and fluid
Irritable Bowel Syndrome
• Symptoms
– Cramps, bloating, increased frequency, diarrhea,
constipation
• Causes
– Altered intestinal peristalsis
– Decreased pain threshold
• Individualized treatment
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Elimination diet
Moderate caffeine
Low-fat, small, frequent meals
Stress reduction
Diarrhea
• Fluidity and frequency
• Causes
– Infections
– Poorly absorbed substances
• Treatment:
– Plenty of fluid
Gallstones
• Symptoms
– Upper right abdominal pain, gas, bloating,
nausea and vomiting
• Treatment
– Removal of gallbladder
Cystic Fibrosis
• Mucous blocks pancreatic ducts
• Impaired digestion of carbohydrates,
protein and fat
• Treatment
– Replacement enzymes
Celiac Disease
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Allergic reaction to gluten
Flattens villi
Limits absorption of nutrients
Treatment
– Elimination of wheat and rye