1. Digestive System

2. There are 400 species of bacteria in the human colon.
On average a person passes gas 14 times a day.
Constipation is caused when too much water is absorbed in the large intestine and poops become dry.
* The small intestine (pronounced in-test-in) is a long tube about 1 and a half to 2 inches around, and about 22 feet long * The large intestine is fatter (3 to 4 inches around), and is about 5 feet long
Food stays in your stomach for 2 to 3 hours

3. Organs of the Digestive System
Mouth
Pharynx
Esophagus
Stomach
Small intestine
Large intestine
Anus

4. Accessory Digestive Organs
Salivary glands
Teeth
Pancreas
Liver & gallbladder

5. Mouth (oral cavity) Incisors Canines Premolars Molars
Lips, cheeks, hard/soft palate, uvula, tongue, teeth
Food enters
mixes with saliva
Masticate
Incisors
Canines
Premolars
Molars
Bolus: chewed & moistened food

6. Pharynx & Esophagus Pharynx
Open area that begins at the back of the mouth
Esophagus
Runs from pharynx to stomach

7. Physiology of Mouth, Pharynx, Esophagus
Food enters in mouth
Physically broken down
Mixed with saliva
Chemical digestion of starch begins
Swallow
Voluntary; bolus
Peristalsis- rhythmic muscular contractions & relaxations

9. Stomach Cardiac sphincter
Muscle between the esophagus & stomach. Closes to prevent food from reentering the esophagus
Pyloric sphincter
Between the stomach & small intestine.

10. Stomach Food breakdown Gastric juice Chemical digestion in the stomach
Chyme- food mixed with gastric juice. 30mL
Ulcer- Food Propulsion
Peristalsis
Pyloric sphincter: barely opens & squirts ~3mL of chyme

11. Stomach Problems Heartburn Cardiac sphincter doesn’t close completely.
Ulcers-stomach lining breaks down

12. Small Intestine Major digestive organ-longest section (~21 ft)
Duodenum
Jejunum
Ileum
Structure
Villi- fingerlike projections
Microvilli- extensions on the villi

15. Small Intestine Food breakdown & absorption (3-6 hrs)
Chemical digestion
Brush border enzymes
Pancreatic juice
Complete starch digestion
Half of protein digestion
Fat digestion
Bile- breaks down large fat globules

16. Large Intestine Colon Ascending Transverse Descending sigmoid Rectum
Anal canal

17. Large Intestine Contains few nutrients “resident bacteria”
Metabolize remaining nutrients
Make vitamin K and B vitamins
Release gases (500 mL per day)
Methane & hydrogen sulfide
Feces
Undigested food residue, mucus, millions of bacteria, water

18. Large Intestine Propulsion Mass movements
Long, slow-moving, powerful contractile waves (3-4 times a day)
Fiber-strengthens contractions
Defecation
Defecation reflex
Anal sphincters

19. Large intestine problems
Diverticulitis-inflammation of diverticula
Diarrhea
Rushes food before it absorbs water
Dehydration & electrolyte imbalance
Constipation
Stool hard & difficult to pass
Lack of fiber; poor bowel habits; laxative abuse