Digestive System

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Digestive System
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Salivary glands
Tongue/mouth
Epiglottis
esophagus
Esophageal sphincter
Liver
Gallbladder
Stomach
Pyloric sphincter
duodenum
Pancreas
Large intestine or colon
Jejunum
Ileum
Appendix
Rectum
Anus
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I. Mouth/Tongue Salivary glands

• Teeth mechanically breaks down food.
• Tongue moves food around the mouth to form a
  bolus.
• Salivary glands release salivary amylase which
  breaks down starch into dextrins
• Saliva also adds moisture for swallowing

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II. Pharynx (throat) and epiglottis

• Pharynx/soft palate prevents food from going up
  the sinus cavities and directs bolus down throat.
• Epiglottis prevents food from entering the
  trachea.

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III. Esophagus

• Moves bolus from mouth to the stomach by
  peristalsis.
• Which kind of muscles?
• What is the function of the lower esophageal
  (cardiac) sphincter?

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IV. Stomach

• Rugae are lined with thousands of gastric pits.
• Pits release pepsin that initiates protein
  digestion.
• What do proteins break down into?

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V. Gastric Pits

• Chief cells at the bottom (2) make pepsinogen,
  which is the inactive form of pepsin.
• Parietal cells (3) release HCl
• As pepsinogen moves up the pit the HCl changes it
  into pepsin.
• Mucous cells (1) secrete mucus. Why?
• What is the advantage of having these cells
  arranged this way?

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VI. Pyloric sphincter

• Pyloric sphincter controls the amount of food
  (chyme) passed into the small intestine.
• Why are there so many ripples (rugae)?

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VII. Small Intestine A. The site of the
greatest digestion and absorption. B. About 21
long divided into three regions duodenum,
jejunum and ileum.

• C. Duodenum (8a) is the first 12 coming off of
  the stomach.
• 1. Receives secretions from the liver,
  gallbladder and pancreas.

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Have many smaller finger like folds called
villi.2. The villi have microvilli3. Why all of
the folds?
D. Circular folds
Circular Folds
Villi
Epithelial Cells
Capillaries
Lymph Vessel
Vein
Artery
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VIII. Liver

• Detoxifies the blood
• Converts foodstuffs
• Stores glycogen, minerals (iron) and fat soluble
  vitamins
• Liver makes bile that emulsifies fat.

• IX. Gallbladder
• A. Concentrates and stores excess bile.
• B. What is jaundice?

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X. Pancreas

• A. Pancreas secretes proteases, carbohydrases,
  and lipases.
• B. Secretes high levels of sodium bicarbonate.
  Why?
• C. What else is secreted by the pancreas?
• D. Is the pancreas an endocrine or exocrine gland?

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XI. Large intestine, Rectum Anus

• Absorbs water and forms feces. How does this
  relate to constipation and diarrhea?
• Produces vitamins with bacterial action
• Rectum stores solid waste.
• What are hemorrhoids?

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XII. Appendix

• Vestigial organ that contained bacteria to aid in
  the breakdown of cellulose walls.
• Appendicitis Inflammation of the appendix due
  to blockage of the lumen by chyme, foreign body,
  carcinoma, stenosis, or kinking.
• Infection may progress to gangrene and
  perforation within 24 to 36 hours