1. Digestive System Physiology

2. Overall Steps Ingestion Secretion (of enzymes) Digestion Absorption
Elimination

3. Mechanical Digestion Mastication- chewing Deglutination- swallowing
Peristalsis & Segmentation

4. Chemical Digestion Enzymes work to digest food by hydrolysis
The function with a negative feedback loop
They are continually being eliminated
The have specific pH under which they function
Examples
amylase, slightly acidic in saliva
pepsin, highly acidic stomach

5. Digestive juices and Enzymes
Chemical Digestion
Location
Digestive juices and Enzymes
Substance Digested
Mouth (Saliva)
Amylase
Starch (polysaccharides)
Stomach (Gastric juice)
Pepsin (protease)
Proteins
HCL
Pancreatic juice
Trypsin (protease)
Lipases
Fats, lipids
Starch
Intestinal Enzymes
Peptidases
Peptides, proteins
Sucrase
Sucrose
Lactase
Lactose
Maltase
Maltose

6. Digestive juices and Enzymes
Chemical Digestion
Location
Digestive juices and Enzymes
Substance Digested
Mouth (Saliva)
Amylase
Starch (polysaccharides)
Stomach (Gastric juice)
Pepsin (protease)
Proteins
HCL
Pancreatic juice
Trypsin (protease)
Lipases
Fats, lipids
Starch
Intestinal Enzymes
Peptidases
Peptides, proteins
Sucrase
Sucrose
Lactase
Lactose
Maltase
Maltose

7. Macromolecule Digestion
Starches(carbohydrates)monosaccharides(glucose)
Proteins(polypeptides) amino acids
Lipids  fatty acids, glycerols

8. Nutrient Digestion Nutrients include Carbohydrates Fats Minerals
Proteins
Vitamins
include
are made of
are made using
include
include
Simple
Complex
Amino acids
Calcium
Iron
Fatty Acids
Glycerol
such as
such as
Sugars
Starches
Fat-soluble
Water-soluble

9. Emulsification of Fats
Micelle
(fat droplet in water)
Fats are insoluble in water and must be broken down into small droplets, or emulsified
Lecithin and bile salts found in bile both act as emulsifying agents
Micelles, tiny fat droplets are formed with lots of surface area
Lipases from pancreatic enzymes can then breakdown fats

10. Digestive Secretions
Saliva is mostly water but also contains digestive enzymes
Mucus is a mixture of water and glycoproteins
Chief cells in stomach secrete gastric enzymes(pepsin)
Parietal cells secrete HCL (activates pepsin) and intrinsic factor into the stomach

11. Absorption Stomach 20% alcohol Aspirin Small Intestines Ca, Mg, Fe
Glucose
Vitamins, Na, K, B12
80% alcohol
Fats
H2O
Colon
Na, K
Rectum
Elimination of feces

12. Elimination Defecation is the process of eliminating feces
Defection reflex is triggered by a filling of the rectum
Constipation results of slow movement of feces causes a high rate of water absorption
Diarrhea is caused by a rapid movement of stool that does not allow for absorption of water, can be fatal is severe and untreated

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14. Disorders of the Digestive System
Gastroenteritis- inflammation of the stomach
Anorexia- chronic loss of appetite
Emesis- vomiting
Nausea- unpleasant feeling before vomiting
Diverticulosis- saclike pouches in the intestines that can become inflamed and infected.

15. Disorders of the Digestive System
Ulcer- open wound or sore in the stomach or small intestine, Caused by H. pylori
Irritable bowel syndrome, IBS- (spastic colon) stress causes diarrhea or constipation
Cirrhosis- when the liver is damaged faster than it can regenerate it develops scar tissue.