1. Digestive Organs

2. Overview
Digestive System

3. Overview Digestive System Alimentary Canal (Gastrointestinal Tract)
The continuous tube that carries food
from the mouth to the anus.

4. Overview Digestive System Alimentary Canal (Gastrointestinal Tract)
The continuous tube that carries food
from the mouth to the anus.
Accessory Digestive Organs
Organs that contribute to the digestion
of food even though food does not pass
directly through these organs.

5. Overview
Digestive Processes

6. Overview Digestive Processes
Mechanical Digestion: The physical breakdown of food.
Ex: Grinding of the teeth or churning of the stomach.

7. Overview Digestive Processes
Mechanical Digestion: The physical breakdown of food.
Ex: Grinding of the teeth or churning of the stomach.
Chemical Digestion: The catabolic breakdown of food using
enzymes and acids.

8. Overview Digestive Processes
Mechanical Digestion: The physical breakdown of food.
Ex: Grinding of the teeth or churning of the stomach.
Chemical Digestion: The catabolic breakdown of food using
enzymes and acids.
Absorption: The passage of digested food from the lumen of
the GI Tract into the blood or lymph.

9. Structures and
Functions of the
Digestive System

10. Mouth

11. Mouth
Tongue: Mixes food.

12. Mouth

13. Mouth
Teeth: Tear and grind food.

14. Mouth
Teeth: Tear and grind food.
Layers
Enamel
Dentin
Pulp

15. Mouth
Teeth: Tear and grind food.
Types

16. Mouth Teeth: Tear and grind food. Types Incisors - chisel-shaped
- cutting

17. Mouth Teeth: Tear and grind food. Types Canines - “eye-teeth”
- tearing

18. Mouth Teeth: Tear and grind food. Types Premolars - Broad crowns
- grinding
Molars

19. Mouth Salivary Glands: Moisten food and contain
enzymes for the breakdown of starchy foods.

20. Salivary Glands
Three pairs of major salivary glands (parotid, submandibular, and sublingual glands) and numerous smaller ones secrete saliva into the oral cavity, where it is mixed with food during mastication. Saliva contains water, mucus, and enzyme amylase.
Functions of saliva include the following:
It has a cleansing action on the teeth.
It moistens and lubricates food during mastication and swallowing.
It dissolves certain molecules so that food can be tasted.
It begins the chemical digestion of starches through the action of amylase, which breaks down polysaccharides into disaccharides

21. Pharynx
Common passageway for food and air.
Pharynx

22. Esophagus
Propels food to the stomach via “peristalsis.”
Esophagus

23. Stomach
Storage of food and digestion of protein.
Stomach

24. Stomach (in detail)
Curvatures
Lesser
Curvature
Greater
Curvature

25. Stomach (in detail) Sphincters Gastroesophageal Sphincter Pyloric

26. Stomach (in detail)
Regions
Fundus
Body
Pyloric
Antrum

27. Stomach (in detail) Rugae: Large, longitudinal folds of the mucosa

28. Small Intestine
Majority of digestion and absorption occurs here.

29. Small Intestine - Sections
Duodenum
First 10 inches of the small intestine.
Collects bile from the liver.
Collects pancreatic juices from the pancreas.
“Sphincter of Oddi” controls entry of the bile and juices.

30. Small Intestine - Sections
Jejunum - Next 8 feet.
Ileum - Final 12 feet.
Ileocecal Valve - The small intestine joins
the cecum of the large intestine.

31. Large Intestine (“Colon”)
Absorbs water and some nutrients.
Large Intestine

32. Large Intestine - Sections
3. Transverse Colon
4. Descending
Colon
2. Ascending
Colon
5. Sigmoid
Colon
6. Rectum
1. Cecum
7. Anus

33. Large Intestine - cont. Taniae coli: Smooth muscle that causes the
colon to “pucker.”
Haustra: Pocket-like sacs.
Appendix: Contains
lymphoid tissue that aids
the immune system.

34. Accessory Organs of Digestion
Liver: Produces bile to aid
in the digestion of lipids.

35. Accessory Organs of Digestion
Gallbladder: Stores bile until
it is released into the small
intestine.

36. Bile Secretion in Detail
The liver is stimulated by the hormones “secretin” and
“cholecystokinin” (CCK) to produce bile.
The bile enters the right and left hepatic ducts and travels to the
common hepatic duct. The bile is stored in the gallbladder.
The gallbladder is stimulated
to release the bile by the
vagal nerve and CCK.
The bile enters the
duodenum via the
bile duct.
Right and left hepatic ducts
Common hepatic duct
Gallbladder
Bile duct
Duodenum

37. Accessory Organs of Digestion
Pancreas: Produces many types
of enzymes used in the small
intestine to digest food.

38. Pancreatic Juice Secretion in Detail
The hormones cholecystokinin and secretin stimulate the release of
pancreatic juices by the pancreas.
The juices travel through the pancreatic ducts to enter the
duodenum.
Pancreas
Duodenum
Main pancreatic duct

39. Control of Digestion - Nervous System
Two Phases:
“Cephalic Phase” - Triggered by the site,
smell, and taste of food. This stimulates the
stomach to prepare for the entry of food.

40. Control of Digestion - Nervous System
Two Phases:
“Cephalic Phase” - Triggered by the site,
smell, and taste of food. This stimulates the
stomach to prepare for the entry of food.
“Gastric Phase” - Stomach distension by food
stimulates the release of gastric juices.

41. Control of Digestion - Hormones
Gastrin - Produced by the stomach; stimulates
the release of gastric juices.

42. Control of Digestion - Hormones
Gastrin - Produced by the stomach; stimulates
the release of gastric juices.
Secretin - Produced by the small intestine;
stimulates the pancreas and gall bladder to release
pancreatic juices and bile.

43. Control of Digestion - Hormones
Gastrin - Produced by the stomach; stimulates
the release of gastric juices.
Secretin - Produced by the small intestine;
stimulates the pancreas and gall bladder to release
pancreatic juices and bile.
Cholecystokinin (CCK) - Produced by the small
intestine; stimulates the pancreas and gall bladder
to release pancreatic juices and bile.

44. Digestive Tract

45. Peptic Ulcer Lesions in the wall of the stomach or duodenum.
Digestive Disorders
Peptic Ulcer
Lesions in the wall of the stomach
or duodenum.
Primarily caused by bacteria.
Treated with antacids AND
antibiotics.

46. Appendicitis Usually caused by fecal obstruction
Digestive Disorders
Appendicitis
Usually caused by fecal obstruction
or anatomical “kinking” of the
appendix.
A rupture leads to peritonitis (ouch)

47. (Inflammation of the Peritoneum)
Digestive Disorders
Peritonitis
(Inflammation of the Peritoneum)
Usually results from an infection caused by a
external or internal penetrating wound.
Bacteria from intestines
enter the sterile areas of the body
surrounding the digestive system.
May cause death if not treated with high
doses of antibiotics.

49. (Inflammation of the liver)
Digestive Disorders
Hepatitis
(Inflammation of the liver)
Caused by drugs, chemicals, viruses,
alcohol, etc.
Viral “Hepatitis A” is usually caused
by the ingestion of food.
Viral “Hepatitis B” and “Hepatitis C”
are “blood-borne” pathogens.

50. Diverticulitis Small bulges (herniations) of the mucosa in
Digestive Disorders
Diverticulitis
Small bulges (herniations) of the mucosa in
The large intestine.
These areas can become inflamed and
possibly rupture.
Prevention is the treatment of choice. A
diet high in fiber will help prevent
diverticulitis.

51. Diverticulitis

52. Emesis (Vomiting) Can be caused by microbes, allergies,
Digestive Disorders
Emesis
(Vomiting)
Can be caused by microbes, allergies,
gluttony, poisons, etc.

53. Diarrhea Movement of fecal material through the GI Tract too rapidly.
Digestive Disorders
Diarrhea
Movement of fecal material through
the GI Tract too rapidly.
May be caused by microbes, spicy
foods, stress, etc.

54. Constipation Infrequent defecation of fecal material.
Digestive Disorders
Constipation
Infrequent defecation of fecal
material.
Usually caused by a diet low in
fiber and water.

55. Cirrhosis of the Liver Condition where liver cells are
Digestive Disorders
Cirrhosis of the Liver
Condition where liver cells are
destroyed and replaced by fibrous
connective tissue.
Alcoholism is a common cause of
cirrhosis.

56. Gall Stones (Biliary Calculi) Crystalization of cholesterol and bile
Digestive Disorders
Gall Stones
(Biliary Calculi)
Crystalization of cholesterol and bile
salts.
Blocks the bile duct or fills the gall
bladder.

57. Gallstones: MRI showing transverse section of abdomen

58. Jaundice Build-up of bile in the skin causing a yellowing of the skin.
Digestive Disorders
Jaundice
Build-up of bile in the skin causing
a yellowing of the skin.
May be caused by damage to the liver,
gall bladder, or any of the ducts that
service these organs.

59. Jaundice

60. Buliemia Nervosa Condition where a patient binges on
Digestive Disorders
Buliemia Nervosa
Condition where a patient binges on
food and then purges with either
laxatives or vomiting.
Considered a psychological disorder
where the patient has a fear of gaining
weight.
Treated with psychotherapy.

61. Anorexia Nervosa Digestive Disorders
Psychological disorder where the patient
has a false perception of their own weight.
Patient denies their own appetite.
Patients are usually % below normal
body weight.
Extreme cases are lethal.
Closely associated with bulimia nervosa.

62. False perception of my weight.
It should never be considered “fashionable”
It can affect men and women

63. Flatulence Excessive intestinal gas resulting
Digestive Disorders
Flatulence
Excessive intestinal gas resulting
from bacteria in the intestines, diet,
or swallowing air.