1. Anatomy & Physiology Mrs. Halkuff
The Digestive System
Anatomy & Physiology
Mrs. Halkuff

2. Functions
Digestion
Absorption
Elimination

3. 2 Types of Digestion 1. Mechanical 2. Chemical
Begins immediately after ingestion
Mastication (chewing) with teeth
Purpose is to break down food into smaller pieces
Peristalsis: Squeezing of food down the esophagus
2. Chemical
Accomplished by digestive enzymes
Enzymes break down large molecules (Fats, Carbohydrates, & Proteins)

4. Enzymes Protease: Breaks down protein Lipase: Breaks down fat
Amylase: Breaks down carbohydrates (starches down to sugars

5. Alimentary Canal Canal connecting mouth to anus. Mouth Pharynx
Esophagus
Stomach
Small Intestines
Large Intestines
Colon
Rectum
Anus

6. Mouth Hard Palate: Roof of mouth (front)
Soft Palate: Roof of mouth (back)
Uvula: Fleshy flap that keeps food from moving up into your nasal cavity when swallowed.
Epiglottis: Elastic cartilage attached to root of tongue that directs air into the trachea and food into the esophagus.
Tongue : Moves food around and allows for taste.
Teeth: Used to break down food into smaller pieces.

7. Coats
Beginning with the pharynx to the anus, the walls of the alimentary canal are composed of two coats:
Mucus Coat
Epithelial Goblet cells line the canal producing mucus.
Muscle Coat
Inner muscles: Circular
Outer muscles: Longitudinal
Both coats facilitate movement of food.

8. Pharynx
Throat
Air, Food, Liquid all mix here.

9. Esophagus Connects the pharynx to the stomach
Pushes food down by peristalsis.
Bolus: Chewed food

10. Stomach “C-shaped” organ that contains acid to break down food.
Food mixes with stomach acid to produce a thick cream called chyme.
Has 3 Regions:
Cardiac: Upper stomach region
Body: Mid stomach region
Pylorus: End stomach region

11. Stomach Sphincters: Muscular valves that control opening & closing.
Cardioesphageal Sphincter: Valve connecting the esophagus to the stomach.
Pyloric Sphincter: Valve connecting the pylorus to the small intestines.

12. Stomach: Curvy & Wrinkly
Curvatures:
Fundus
Greater Curvature
Lesser Curvature
Rugae: Internal stomach wrinkles
Fewer rugae when full
More rugae when empty

13. Small Intestine Main function is absorption of nutrients
Has 3 divisions:
Duodenum
Jejunum
Ileum

14. Duodenum First segment of the small intestine Connects to stomach
Receives chyme from stomach
Regulates gastric emptying
Continues digestion
Signals hunger cues
Stimulates the liver, gall bladder, & pancreas
In gastric bypass surgery, the duodenum is usually bypassed.

15. Jejunum
Second segment of the small intestine
Finalizes food digestion

16. Ileum Third & final segment of the small intestine
Main function is to absorb nutrients
Returns bile back to liver
Connects to the large intestine by the ileocecal valve

17. Large Intestine
Watery waste is passed from the small intestine to large intestine.
Main function is to absorb any water or minerals from the waste.
Compresses waste into compact form for easy removal from the body.
Chyme combines with mucus and bacteria and is converted to feces.

18. Large Intestine
4 divisions:
1. Cecum
2. Colon
3. Rectum
4. Anal Canal

19. Cecum First segment of large intestine.
Connection at the small intestine at ileocecal valve.

20. Colon 4 segments named for their relation to the pelvis:
1. Ascending colon
2. Transverse colon
3. Descending colon
4. Sigmoid colon

21. Rectum
Collects feces accumulated in the colon.

22. Anal Canal Short tube (1.5”) 2 muscular rings
Involuntary (Internal muscle)
Voluntary (External muscle)
These muscles relax to allow for
defecation.