2404digestivesystem12_04_06.ppt DIGESTIVE SYSTEM PRESENTATION

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1. Overview of the Digestive System
Digestive Tract:
Mouth, pharynx, and
esophagus, stomach,
small intestine, and
large intestine (colon)
Accessory Organs:
Teeth, tongue, salivary
glands, pancreas, liver,
and gallbladder

2. Functions of the Digestive System
•Ingestion
•Mechanical
processing
•Chemical
digestion
•Secretion
•Absorption
•Excretion

3. Histology of the Digestive Tract
Mucosa
Submucosa
Muscularis
Externa
Serosa

4. Mucosa (Innermost Layer)
•Epithelium
•Connective
Tissue
(Blood
vessels,
lymphatic
vessels,
lymphatic
nodules)
•Smooth
Muscle

5. Submucosa
Connective tissue
•Blood vessels
•Lymphatic
vessels
•Nerve plexus
•May have glands
and lymphatic
tissue

6. Muscularis Externa
Smooth or Skeletal Muscle
If smooth muscle, usually 2 layers (circular and
longitudinal)

7. Adventitia or Serosa
Adventitia
(organs
superior to
diaphragm)
Serosa =
visceral
peritoneum

8. Small Intestine: Peyer’s Patches

9. Components of the Digestive System
GI Tract:
•Oral Cavity
•Pharynx
•Esophagus
•Stomach
•Small
Intestine
•Large
Intestine

10. Oral Cavity

11. Oral Cavity

12. The Pharynx
•Nasopharynx
•Oropharynx
•Laryngopharynx

13. The Esophagus

14. The Esophagus
•Stratified
squamous
epithelium
•Mucous glands
•Muscularis
externa –
skeletal muscle
first third of
length

15. Peristalsis in Esophagus
LE 21-8
Bolus of
food
Muscles relax,
allowing
passageway
to open
Stomach
Muscles
contract,
constricting
passageway
and pushing
bolus down
Muscles
relax
Muscles contract
Muscles relax
Muscles contract

16. Stomach
•Site where
food is
churned into
chyme
•Protein
digestion
begins

17. Stomach

18. Stomach

19. Stomach – Microscopic Anatomy

20. Stomach – Microscopic Anatomy

21. The Stomach – Microscopic Anatomy

22. Ulcers in stomach
Helicobacter pylori

23. Small Intestine – Gross Anatomy
•Longest portion of
the alimentary canal
•Site of most
enzymatic digestion
and absorption
•Three subdivisions
•Duodenum,
jejunum, and ileum

24. Duodenum and Related Organs
LE 21-11a
Liver
Bile
Gall-
bladder
Bile
Duodenum of
small intestine
Acid chyme
Pancreatic
juice
Intestinal enzymes
Stomach
Pancreas

25. Duodenum and Related Organs

26. Enzymes in Small Intestine

27. Small Intestine – Microscopic Anatomy

28. LE 21-11b
Vein
with blood
en route to
the liver
Muscle
layers
Lumen
Large
circular folds
Villi
Nutrient
absorption
Lymph
vessel
Intestinal wall
Villi
Blood
capillaries
Epithelial
cells
Nutrient
absorption
Lumen of intestine
Epithelial cells
Lymph
Blood
Fats
Amino
acids
and
sugars
Fatty
acids
and
glycerol
Nutrient absorption
into epithelial cells
Microvilli

29. Small Intestine: Duodenum
Br = Brunner glands
V = Villus
G = Goblet cells
Cr = Intestinal glands
MM = Muscularis
Mucosae
LP = Lamina Propria

30. The Small Intestine – Structural Features

31. Gross Anatomy of Large Intestine
•Cecum
•Appendix
•Ascending
•Transverse
•Descending
•Sigmoid colon
•Rectum
•Anus

32. LE 21-12
Large
intestine
(colon)
Sphincter
End
of small
intestine
Nutrient
flow
Appendix
Cecum
Anus
Rectum
Small
intestine

33. Gross Anatomy of Large Intestine
•Rectum – descends along the inferior half of the
sacrum
•Anal Canal – the last subdivision of the large
intestine

34. Gross Anatomy of Large Intestine

35. Microscopic Anatomy of Large Intestine
•Villi are absent
•Contains numerous goblet cells
•Intestinal crypts – simple tubular glands
•Lined with simple columnar epithelial tissue
•Epithelium changes at anal canal
•Becomes stratified squamous epithelium

36. Microscopic Anatomy of Large Intestine

37. Teeth

38. Salivary Glands

39. Pancreas

40. Exocrine Pancreas: Histology

41. Liver
•Largest gland in the body
•Performs over 500 functions
•Digestive function – bile production
•Performs many metabolic functions

42. Visceral Surface of the Liver

43. Microscopic Anatomy of Liver

44. Microscopic Anatomy of Liver

45. Gallbladder
•Stores and concentrates bile
•Expels bile into duodenum
•Bile emulsifies fats

46. Gallbladder

47. Enzymes in Small Intestine

48. The Peritoneal Cavity and Peritoneum
•Mesentery – a
double layer of
peritoneum
•Holds organs in
place
•Sites of fat
storage
•Provides a route
for circulatory
vessels and
nerves

49. Mesenteries
•Superficial view of
the abdominal
organs

50. Mesenteries
•Greater omentum and
transverse colon
reflected

51. Mesenteries
•Sagittal section through
the abdominopelvic
cavity

52. Segmentation
•Rhythmic local
contractions of the
intestine
•Mixes food with
digestive juices

53. Disorders of the Digestive System
•Intestinal obstruction
•Mechanical obstructions
•Adhesions, tumors, or foreign objects
•Nonmechanical obstruction
•Halt in peristalsis
•Trauma
•Intestines touched during surgery

54. Disorders of the Digestive System
•Inflammatory bowel disease
•Inflammation of intestinal wall
•Crohn’s disease
•Ulcerative colitis
•Viral hepatitis – jaundice and flu-like symptoms
•Major types – A, B, C, and G
•Cystic Fibrosis and the Pancreas

55. The Digestive System in Later Life
•Middle age – gallstones and ulcers
•Old age – activity of digestive organs decline
•Fewer digestive juices and enzymes produced
•Absorption is less efficient
•Dehydration of fecal mass leads to constipation
•Diverticulosis and cancer of digestive organs