The digestive system breaks down complex foods into simpler forms that can be absorbed by the body. Digestion begins in the mouth through chewing and the addition of saliva to form a bolus, which is then moved through the esophagus via peristalsis. The major structures of the digestive system include the mouth, esophagus, stomach, small intestine, large intestine, and accessory organs like the pancreas and liver.

2. The process of changing complex solid foods into
simpler soluble forms which can be absorbed by
body cells.
BOLUS – soft, pliable ball – created from
chewing and addition of saliva – it slides down
esophagus
PERISTALSIS – wavelike motions, moves food
along esophagus, stomach and intestines
DIGESTION

3. Structures of the digestive system
Digestive system
 Also known as:
 Alimentary Canal
 Digestive Tract
 Gastrointestinal
Tract
 Upper GI
 Lower GI
 Over 30’ in length
from mouth to anus
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4. Primary structures
 Mouth
 Esophagus
 Stomach
 Small intestines
 Large intestines
Accessory structures
 Tongue
 Teeth
 Salivary glands
 Pancreas
 Liver
 Gall bladder
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Structures of the digestive system

5. Structures of the digestive system
Mouth
 (buccal cavity)
 Tongue
 Teeth
 Salivary Glands
 Palate
 Uvula
 The physical
breakdown of food
begins here
first…digestion
begins in the
mouth 5

6. Structures of the digestive system
Tongue
 Attached to floor of
mouth
 Made of skeletal
muscle attached to
four bones
 Taste buds on the
surface
 Sweet
 Sour
 Bitter
 Salty
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7. Structures of the digestive system
Teeth
 Primary (deciduous)
 20 “baby teeth”
 Secondary
(permanent)
 32 “adult teeth”
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8. Structures of the digestive system
 Salivary glands
 Parotid gland
 Largest salivary gland
 Ptyalin in saliva converts
starches to simple
sugars causes the initial
chemical breakdown.
 Submandibular gland
 Sublingual gland
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9. Structures of the digestive system
Palate – separates the
mouth from the nasal
cavity
 Hard
 Soft
Uvula
 Flap of skin
hanging in the
back of the throat
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10. Structures of the digestive system
 Pharynx (throat)
 Nasopharynx
 Oropharynx
 Hypopharynx
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11. Structures of the digestive system
 Esophagus
 Muscular tube, 10”
long
 Connects the pharynx
and stomach
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12. Structures of the digestive system
 Stomach
 Upper left
quadrant of the of
the abdominal
cavity
 Fundus
 Body
 Pylorus
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13. Cardiac sphincter - controls passage of food into
stomach and keeps it from going back into the
throat.
PYLORIC SPHINCTER – valve, regulates the
entrance of food into duodenum
RUGAE – mucous coat lining of stomach in folds
when the stomach is empty
Stomach has muscular coat that allows it to
contract (peristalsis) and push food into the small
intestine

15. Structures of the digestive system
 Small intestines – main
function is absorption of
NUTRIENTS
 Duodenum
 First segment
 12’ long
 Jejunum
 Second segment
 8’ long
 Ileum
 Third segment
 10-12’ long
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16. Structures of the digestive system
 Large intestines
 Approximately 2” in
diameter
 5’ long
 Responsible for
elimination of waste
and absorption of
water
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17. Functions of the digestive system
Teeth
 Define mastication.
 How is the tooth’s shape
related to its function?
 Incisors
 Cuspids
 Bicuspids
 Molars
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18. Accessory Organs of Digestion
PANCREAS
 Located behind stomach
 Exocrine function – secretes digestive
enzymes to break down food.
 Also has endocrine function.
 Feather shaped organ

19. Functions of the digestive system
Liver
 Produce and store glucose in the form of
GLYCOGEN
 Detoxify alcohol, drugs and other harmful
substances
 Manufacture blood proteins
 Manufactures bile
 Store Vitamins A, D and B complex
 Connects to gall bladder and small intestine
by ducts
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20. Functions of the digestive system
Gallbladder
 Small muscular green
sac that secretes and
stores bile
 Located in the right upper
quadrant of abdominal
cavity.
 When fatty foods
digested, bile released by
gallbladder
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21. Functions of the digestive system
 Large intestine
 CHYME – semi-liquid food and
gastric juices
 Approx 2” in diameter
 Also called the colon
 CECUM – lower right portion of large
intestine
 APPENDIX-blind sac attached to
cecum, having no known function
 RECTUM – last portion of large
intestine
 ANUS – external opening of the Lg.
intestine
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22. Disorders of the digestive system
 Anorexia
 Decreased or poor
appetite
 Symptom
 Anorexia nervosa
 Eating disorder
characterized by
refusal to eat
 Psychiatric disorder
Bulimia nervosa
(binge eating and
purging) is a
psychiatric disorder
as well 22

23. Obesity is one of the common eating disorders in the United
States.
A person is considered obese if their BMI (body mass index
is above 30.
How to calculate BMI:
BMI =
( lbs/inches² )
(weight in pounds * 703 )
————————————
height in inches²
BMI Weight Status
Below 18.5 Underweight
18.5 -24.9 Normal
25 - 29.9 Overweight
30 & Above Obese

24. Disorders of the digestive system
Caries
 Cavities
How often should you
brush and floss?
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25. Disorders of the digestive system
Cholecystitis
 Inflammation of the gall bladder
 Sx = pain that radiates to right
shoulder…frequently after
eating fatty foods
 How is it treated? -
cholecystectomy
 Cholelithiasis – gall stones
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26. Disorders of the digestive system
Cleft palate
 Hard and/or soft
palate doesn’t close
completely during
fetal development
 Problems swallowing
 Surgery needed to
repair
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27. Disorders of the digestive system
Cirrhosis
27
Chronic, progressive
disease of liver
Normal tissue replaced by
fibrous connective tissue.
75% caused by excessive
alcohol consumption (also
caused by Tylenol use)

28. Disorders of the digestive system
Constipation
 When defecation delayed,
feces become dry and
hard
 Rx – diet with cereals,
fruits, vegetables,
(roughage), drinking
plenty of fluids, exercise,
and avoiding tension
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29. Disorders of the digestive disorders
Diarrhea
 Loose, watery,
frequent bowel
movements when
feces pass along
colon too rapidly
 Caused by infection,
poor diet,
nervousness, toxic
substances or
irritants in food
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30. Disorders of the digestive disorders
Gastroenteritis
 Inflammation of mucous
membrane lining of
stomach and intestine
 Common cause = virus
 Sxs – nausea, vomiting,
diarrhea for 24-36 hours
 Complication = dehydration
 Prevention…good
handwashing 30

31. Disorders of the digestive system
Gastroesophageal
reflux disease
(GERD)
 Reflux of gastric acid
into the espohagus
 Sx – burning
sensation that often
worsens with laying
flat…gets better
with sitting up or
raising head of bed
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32. Disorders of the digestive system
Hepatitis
 Acute
 Chronic
 Hepatitis A
(contaminated food or
water borne), B
(blood borne), C
(blood borne), D, E
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33. Disorders of the digestive system
Irritable bowel syndrome
 Cause unknown
Sx – abdmonial pain,
bloating, diarrhea and
constipation (alternating)
Trt – lifestyle and diet
changes, medication
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34. Disorders of the digestive system
Chron’s Disease
and Ulcerative
Colitis
• Autoimmune disorders
• Type of inflammatory
bowel disease
• Sxs – abdominal pain,
severe diarrhea,
malnutrition

35. Disorders of the digestive system
 Peptic ulcer - Sore or
lesion that forms in the
mucosal lining of the
stomach
 Gastric ulcers in the stomach
and duodenal ulcers in the
duodenum
 Cause – H. pylori (bacteria) is
primary cause
 Lifestyle factors that
contribute: cigarette smoking,
alcohol, stress, certain drugs
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36. Relevance of nutrition to the
digestive system
 Vitamins
 Fat soluble
 Vitamins A, D, E, K
 Water soluble
 Vitamins C, B
 Proteins aid in wound
healing
 Carbohydrates such as
bread and pasta offer
quick energy
 Electrolytes
 Calcium
 Chloride
 Magnesium
 Phosphorus
 Potassium
 Sodium
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