1. The Human Body: From Food to Fuel Chapter 41

2. The Gastrointestinal Tract
Organization
Mouth  anus
Accessory organs
Salivary glands, liver, pancreas, gallbladder 2

3. Organization of the Gastrointestinal Tract
Functions
Ingestion
Transport
Secretion
Absorption
Movement
Elimination 3

4. Organization of the Gastrointestinal Tract
Layers
Mucosa
Circular muscle
Longitudinal muscle
Spincter 4

5. Overview of Digestion Physical movement Chemical breakdown Peristalsis
Segmentation
Chemical breakdown
Enzymes
Other secretions
Acid
Base
Bile
Mucus 5

6. Overview of Absorption
The road to nutrition absorption
Passive diffusion
Facilitated diffusion
Active transport 6

7. Assisting Organs Salivary glands Moisten food Supply enzymes Liver
Produces bile
“Chemical factory”
Gallbladder
Stores and secretes bile
Pancreas
Secretes bicarbonate
Secretes enzymes 7

8. Putting It All Together: Digestion and Absorption
Mouth
Enzymes
Salivary amylase acts on starch
Lingual lipase acts on fat
Saliva
Moistens food for swallowing
Esophagus
Transports food to stomach
Esophageal sphincter 8

9. Putting It All Together: Digestion and Absorption
Stomach
Hydrochloric acid prepares protein for digestion and activates enzymes
Pepsin begins protein digestion
Gastric lipase has some fat digestion
Gastrin (hormone) stimulates gastric secretion and movement
Intrinsic factor is needed for absorption of vitamin B12 9

10. Putting It All Together: Digestion and Absorption
Small intestine
Sections of small intestine
Duodenum, jejunum, ileum
Digestion
Bicarbonate neutralizes stomach acid
Pancreatic and intestinal enzymes
Carbohydrates
Fat
Protein 10

11. Putting It All Together: Digestion and Absorption
Small intestine
Absorption
Folds, villi, and microvilli expand absorptive surface
Most nutrients absorbed here
Fat-soluble nutrients go into lymph
Other nutrients go into blood 11

12. Putting It All Together: Digestion and Absorption
Large intestine
Digestion
Nutrient digestion already complete
Some digestion of fiber by bacteria
Absorption
Water
Sodium, potassium, chloride
Vitamin K (produced by bacteria)
Elimination 12

13. Circulation of Nutrients
Vascular system
Veins and arteries
Carries oxygen and nutrients to tissues
Removes wastes
Lymphatic system
Vessels that drain lymph 13

14. Circulation of Nutrients
Excretion and elimination
Lungs
Excrete water and carbon dioxide
Kidneys filter blood
Excrete waste; maintain water and ion balance 14

15. Signaling Systems: Command, Control, Defense
Nervous system
Regulates GI activity
Enteric nervous system
Autonomic nervous system
Hormonal system
Increases or decreases GI activity 15

16. Signaling Systems: Command, Control, Defense
Immune system
Protects us from foreign invaders
Role of GI tract
Barrier
Immune response
Natural killer cells
Macrophages
Location of lymphoid tissues
Lymphocytes
Antibodies 16

17. Influences on Digestion and Absorption
Psychological influences
Taste, smell, and presentation of food
Chemical influences
Type of protein you eat and the way it is prepared
Bacterial influences
Hydrochloric acid 17

18. Nutrition and GI Disorders
Constipation
Hard, dry, infrequent stools
Reduced by high fiber, fluid intake, exercise
Diarrhea
Loose, watery, frequent stools
Symptom of diseases/infections
Can cause dehydration
Broth, tea, toast, and other low-fiber foods can help reduce 18

19. Nutrition and GI Disorders
Diverticulosis
Pouches along colon
High-fiber diet reduces formation
Heartburn and GERD
Reduced by smaller meals, less fat 19

20. Nutrition and GI Disorders
Irritable bowel syndrome
Stress and certain foods aggravate the symptoms
Controlled by diet and lifestyle modifications
Reduce stress 20

21. Nutrition and GI Disorders
Colorectal cancer
Fiber-rich diet may reduce risk
Gas
Most foods that contain carbohydrates can cause
Ulcers
Bacterial cause (H. Pylori) 21

22. Nutrition and GI Disorders
Functional dyspepsia
Chronic pain in the upper abdomen
Treat with medicine and stress-reduction 22