1. The Digestive System Structures
Identify the basic structures of the digestive system

2. Oral Cavity
lips
teeth
tongue
hard and soft palate
salivary glands

3. Teeth gathers, cuts, grinds food firmly embedded in bone
carnivores - sharper
herbivores - flatter
deciduous teeth - temporary teeth that are replaced by permanent ones

4. Tooth Anatomy crown - portion of a tooth above the gum line or gingiva
covered in enamel
root - portion of a tooth below the gum line; anchors tooth to bone
twice as long as the crown

5. Tooth Anatomy incisors - foremost teeth used to bite into food
canines - longest teeth used for tearing at food
premolars - teeth used for crushing and grinding food
molars - caudal most teeth used for crushing and grinding food

6. Dental Formulas Numbers represent tooth count on ONE side of the mouth
Upper # represents maxillary teeth, lower # represents mandibular teeth
Letter represents type of tooth.
Canines: {I3/3: C1/1: P4/4: M2/3} = 42

7. Oral Cavity, cont.
Saliva - necessary digestive enzyme produced by salivary glands
Tongue - skeletal muscle that aids in chewing
forms a bolus to be swallowed once food is ground up

8. Esophagus layered tube that extends from the pharynx into the stomach
peristalsis - organized contractions that allow passage of material (food)
sphincter - circular muscle at end of esophagus that opens to allow passage of food

9. Stomach
cardia - inlet region of stomach associated with esophagus (sphincter)
body - storage region
fundus - storage region that allows expansion
antrum - region leading into small intestine
pyloris - controls flow into small intestine (sphincter)

10. Liver lies directly in front of the stomach processes nutrients
secretes bile (secretion that aids in digestion)

11. Small Intestine
duodenum - first short section; associated with pancreas
jejunum - long middle region
ileum - terminal region of small intestine

12. Large Intestine
AKA colon
main function is absorption of water

13. Rectum termination of the intestinal tract
exits the body at anus (sphincter that controls defecation)

14. Additional Structures
peritoneum - smooth epithelial lining of abdomen
mesentery - extension of the peritoneum; carries blood vessels and nerves to small intestine
omentum - surrounds abdominal organs; also carries blood vessels

15. Monogastric Digestion

16. Oral Cavity where food enters mechanical breakdown begins
saliva starts digestion

17. Esophagus musculome mbranous tube extends from pharynx to stomach
peristalsis

18. Stomach chamber, adds gastric juices to food
Hydrochloric Acid
break food into smaller particles

19. Small Intestine complex tube
takes food particles not absorbed by stomach
duodenum, jejunum, ileum

20. Cecum
blind pouch at beginning of large intestine
little function

21. Large Intestine last major organ of tract
main function = absorption of water
reservoir for waste

22. Rectum
terminal portion
opening = anus
undigested food passes as waste

23. Hind-Gut Fermenters

24. guinea pigs, horses, rabbits
one stomach
additional need to digest plant fiber from grass/hay
microbial fermentation

25. Oral Cavity selects pieces of forage with sensitive prehensile lips
grinds up food before swallowing

26. Esophagus carries food to stomach enters stomach at acute angle
cannot vomit!!!!

27. Stomach small stomachs limits amount of food intake
continuous foraging, picking at food

28. Small Intestine major digestive organ
% all nutrients absorbed from here

29. Cecum hind-gut first part of large intestine
ferments plant fiber using microbes

30. Large Intestine
similar to monogastric
absorption

31. Rectum
terminal portion
opening = anus
forms fecal balls

32. Ruminant Digestion

33. 4 chambered stomach
regurgitation
rumination

34. Oral Cavity lips are tough long course tongues for grabbing food
chew and grind food LESS
swallows course bits

35. Esophagus
musculome mbranous tube
carries food to stomach
peristalsis

36. Stomach
4 chambers
Rumen
Reticulum
Omasum
Abomasum

37. Rumen
first chamber food enters
microbes for digestion
fermenting vat

38. Reticulum
second chamber
collects indigestible particles (metals)

39. Rumination
regurgitation of food for re-chewing
“chewing cud”

40. Omasum
third stomach chamber
food enters after rumination

41. Abomasum
fourth chamber
True stomach
gastric juices are secreted

42. Small Intestine complex tube
moves food from stomach to large intestine

43. Cecum blind pouch at beginning of large intestine
little function like monogastric s

44. Large Intestine last major organ function = absorption
reservoir for waste

45. Rectum terminal portion opening = anus removes waste
very runny stool= little wasted