1. The DIGESTIVE System

2. Digestive System Functions
Digestion-breaking down of food by both mechanical and chemical means
Absorption-passage of digested food into the blood stream
Defecation (excretion)-elimination of indigestible substances
Ingestion-taking food into the body (eating)
Movement (propulsion)-passage of food along the alimentary canal

3. Chemical vs Mechanical Digestion
Chemical: Enzymes break down food to smaller molecules for absorption
Mechanical: broken down into smaller parts--MASTICATION and MACERATION

4. Alimentary canal Tube food passes through
Begins at mouth - ends with anus
Food is chewed
Bolus created
Bolus swallowed

5. Pharynx Bolus moves into pharynx Medical term for throat
Has three parts
Nasopharynx
Oropharynx
Laryngopharynx

6. Esophagus 8-12 inches long Smooth muscle contractions called:
peristalsis
Cardiac (aka Gastroesophageal) sphincter
Has no mucous membrane to protect from HCl from stomach

7. Stomach J-shaped 3 sets of muscle in different directions
HCl= chemical breakdown
Pepsin begins protein digestion
Contain rugae to increase surface area
Change bolus into chyme
Mucus protects stomach lining

8. Small intestine
3 parts
Duodenum--most chemical digestion takes place here
Jejunum-absorption continues
Ileum absorption continues
15-22 ft long
Absorbs some of the water in food & what you drink
Nutrients are absorbed through structures called villi

9. Large intestine Called the colon
Main function is water absorption + Vit K absorption
Begins with cecum-contains lymphatic organ called appendix

10. Large intestine Ascending colon Transverse colon-makes hunger sounds
Descending colon
Sigmoid colon
Rectum
Anal canal
Anus

11. Accessory organs CONTRIBUTE to digestion process
NOT part of the canal or tube
Food DOES NOT pass through them

12. Tongue and teeth Teeth break food down into smaller pieces
Tongue moves food to the back of throat

13. Parts of a tooth Crown = exposed portion above gum line
Neck = between crown & root
Gingivae = gums
Root = one to three-- embedded in mandible & maxillae

14. Parts of a tooth Enamel = outermost part, protects from wear & tear
the hardest substance in the body
Dentin = calcified connective tissue
Gives tooth it’s basic shape & rigidity

15. Parts of a tooth
Pulp Cavity = large cavity enclosed by dentin--filled with pulp
Cementum = bone-like substance covers dentin of roots

16. Parts of a tooth Periodontal Ligament
an area of dense fibrous connective tissue
anchors teeth in position
serves as a shock absorber when chewing

17. Salivary glands
6 total--3 pair
parotid
submandibular
sublingual

18. Salivary glands Saliva is mostly water
Enzymes that digest carbs—Amylase—breaks starch into maltose
Softens and moistens food

19. Liver and Gall Bladder Liver makes bile
Bile is stored in gall bladder (sac)
Bile breaks down fats--emulsification
Secreted as it is needed
Eliminated through intestines

20. Pancreas Located posterior to stomach
Secretes enzymes to chemically breakdown fats, carbs, and proteins
Increases pH of chyme
Pancreatic juice—thru pancreatic duct—thru heptopancreatic sphincter

21. Mastication Chewing--makes bolus Teeth mechanically break down food
Food is mixed with saliva

22. Deglutition Swallowing Tongue pushes food to back of throat
Oropharynx--second part of throat
Smooth Muscles contract causing peristalsis
Voluntary

23. Peristalsis
General term for wave-like contractions in esophagus and intestines
Rhythmic smooth muscle contractions

24. Maceration
Stomach contracts and bolus mixed with gastric juices and HCl until it is liquid-like
Bolus is changed to chyme
Empties through pyloric sphincter

25. Segmental contraction
Each segment of small intestine contracts
Helps mix bile and pancreatic juices with chyme
Smooth muscle contractions peristalsis in each segment

26. Absorption Nutrients absorbed in jejunum and illeum
Some nutrients & water absorbed thru stomach
Some water absorbed through small intestine
Most water absorbed through large intestine

27. Haustral churning Each segment in large intestine is called a haustra
Smooth muscle contractions move contents along (type of peristalsis)
Water is absorbed in large intestine

28. Defecation Elimination of material that is undigestible
Plant fiber--necessary for health of the intestines
Formation of feces and elimination of feces

29. Nutrients are broken down in different places in digestive system
Carbohydrates
Begin digestion in mouth with enzyme AMYLASE from salivary glands
Amylase breakdown continues in stomach
Finish breakdown in duodenum (pancreatic juice)

30. Fats Fats begin mixing with gastric juices in stomach
Bile from gall bladder goes into small intestine to break them down
Pancreas secretes enzymes (lipase) to finish chemical breakdown

31. Proteins Begin mixing with pepsin in stomach
Finish with secretions from pancreas into duodenum

32. Digestive System End

33. Digestive System Diseases and Disorders

34. Appendicitis Inflammation of the appendix
Caused by an obstruction by fecal material, a foreign body, stenosis, kinking of the organ, or carcinoma

35. Cirrhosis of the Liver
Scarred liver tissue due to chronic inflammation
Caused by hepatitis, chemical exposure, parasites, and alcoholism
Symptoms include: jaundice, bleeding, edema, and increased sensitivity to drugs and chemicals

36. Tumors of the Digestive System
Can occur in all areas of the digestive system
Can be malignant or benign
Colorectal cancer
3rd most common cause of cancer for both males and females
Overall mortality rate is over 60%
Factors contributing to colorectal cancer include genetic predisposition, diet high in fat, protein, insufficient dietary fiber, and low calcium and selenium in the diet

37. Gall Stones Crystallization of bile in the gallbladder
Can block the bile duct causing intense pain
Usually treated with gall stone dissolving drugs, lithotripsy, or surgery

38. Hepatitis Inflammation of the liver
Can be caused by viruses, drugs, and certain chemicals including steroids and alcohol
Many different types of Hepatitis including:
Hepatitis A (Infectious Hepatitis)
Hepatitis B (Serum Hepatitis)

39. Hepatitis A Infectious hepatitis caused by hepatitis A virus
Spread by fecal contamination of food, clothing, toys, eating utensils, etc.
Mild disease of children and young adults
Characterized by anorexia, malaise, jaundice, nausea, diarrhea, fever, and chills

40. Hepatitis B Serum hepatitis
Caused by the Hepatitis B virus--cause is often unknown or may be:
Transmitted by sexual contact, contaminated syringes, transfusion equipment, saliva, tears, and puncture wounds in the skin
Can produce cirrhosis and possibly cancer of the liver

41. Obesity Excess body fat--20% for men, 30% for women
Currently over 50% of U.S. population is clinically classified as obese
14% of all male cancers linked to obesity
20% of all female cancers linked to obesity

42. Peptic Ulcers
Crater like lesions that develop in the gastrointestinal tract
Most commonly caused by a bacterial infection or chronic use of aspirin, ibuprofen or naproxen