1. Digestive System Structures 2.07
AKA:
Alimentary Canal
Digestive Tract
Gastrointestinal Tract
Upper GI
Lower GI
Approximately 30’ in length from mouth to anus
2.07 Remember the structures of the
digestive system

2. Functions of the Digestive System
Physical breakdown of food.
Chemical digestion of food into the end products of fat, carbohydrates, and protein.
Absorb nutrients into blood capillaries of the small intestines.
Eliminate waste products of digestion.

3. Definitions
Digestion- the process of changing complex solid foods into simpler soluble forms which can be absorbed by body cells
Enzymes- chemical substances that promote chemical reactions in living things

4. Digestion Terminology
Bolus:
soft, pliable ball
created from chewing and addition of saliva-
slides down esophagus.
Peristalsis:
wavelike motions, moves food along esophagus, stomach
and intestines.

5. Definitions
Feces:
undigested semi-solid consisting of bacteria, waste products, mucous and
Cellulose
Defecation:
large intestine fills, defecation reflex triggered-
colon and rectal muscles contract while internal sphincter relaxes
external anal sphincter under conscious control

6. Digestive System Structures
Primary structures
Mouth
Esophagus
Stomach
Small intestines
Large intestines
Accessory structures
Tongue
Teeth
Salivary glands
Pancreas
Liver
Gall bladder
2.07 Remember the structures of the
digestive system

7. In the mouth… Saliva softens food to make it easier to swallow
Ptyalin in saliva converts starches into simple sugar
Under nervous control- just thinking of food can cause your mouth to water.

8. Structure of Organs of Digestion
Mouth
Food enters digestive system through mouth (buccal cavity)
covered with mucous membrane
Roof of mouth is HARD PALATE (bone) and soft palate
UVULA- flap that hangs off soft palate-prevents food from going up the nose when you swallow.

9. 2.07 Remember the structures of the
Buccal cavity
Tongue
Teeth
Salivary Glands
Palate
Uvula
2.07 Remember the structures of the
digestive system

10. Tongue Attached to floor of mouth Helps in chewing and swallowing
Made of skeletal muscle attached to four bones
Papillae (taste buds) on the surface

11. 2.07 Remember the structures of the
Tongue
Taste buds on the surface
Sweet
Sour
Bitter
Salty
2.07 Remember the structures of the
digestive system

12. Salivary Glands Three pairs of glands
Parotid gland
Submandibular gland
Sublingual gland
PAROTID – largest salivary glands, become inflamed during mumps
Secrete saliva

13. Teeth Gingiva – gums, support and protect teeth
Mastication – chewing, teeth helps in mechanical digestion
Deciduous teeth- baby teeth (#20)
Adult mouth has 32 teeth (Permanent).
Did you know???
Canine teeth are also
known as cuspids and
eye teeth.

14. 2.07 Remember the structures of the
Palate
Hard
Soft
Uvula
Flap of skin
hanging in the
back of the throat
2.07 Remember the structures of the
digestive system

15. 2.07 Remember the structures of the
Pharynx (throat)
Nasopharynx
Oropharynx
Hypopharynx
2.07 Remember the structures of the
digestive system

16. Esophagus Muscular tube 10” long Connects pharynx and stomach
Esophageal wall layers
Mucosa
Submucosa
Muscular
External serous

17. In the Stomach… Gastric (digestive) juices are released
Stomach walls churn and mix (This mixture is chyme)
Small amount of chyme enters duodenum at a time controlled by pyloric sphincter
Takes 2-4 hours for stomach to empty.
When will Meagan’s stomach be empty if she last ate at 9a.m.?

18. Stomach Upper left quadrant of the of the abdominal cavity
Fundus
Body
Pylorus
Stomach has muscular coat that allows it to contract (peristalsis) and push food into the small intestine

19. 2.07 Remember the structures of the
Stomach
CARDIAC SPHINCTER-circular layer of muscle, controls passage of food into stomach
PYLORIC SPHINCTER- valve, regulates the entrance of food into duodenum
RUGAE- mucous coat lining of stomach in folds when the stomach is empty
2.07 Remember the structures of the
digestive system

20. Small Intestines Where digestion is completed and absorption occurs
Addition of enzymes from the pancreas and bile from liver/gallbladder

21. Small Intestines
DUODENUM- first segment, curves around pancreas, 12” long
JEJUNUM- Second segment , 8 ft. long
ILEUM- Third segment, ft long
ABSORPTION- in small intestine, digested food passes into bloodstream and on to body cells, indigestible passes on to large intestine

22. 2.07 Remember the structures of the
Acessory organs
Pancreas
Secretes digestive enzymes
Located behind stomach
Liver
Next slide
Gall Bladder
Stores and concentrates bile until needed by body
2.07 Remember the structures of the
digestive system

23. Liver Largest organ in the body
Located below the diaphragm, upper right quadrant
Manufactures bile
Connected to gallbladder and small intestine by ducts
Functions: produce and store glucose in the form of GYCOGEN-
Detoxify alcohol, drugs and other harmful substances
Manufacture blood proteins
Prepare urea from the breakdown of amino acids
Store Vitamins A, D, and B complex

24. Gallbladder Small green muscular sac secretes bile
located inferior surface of the liver
Stores and concentrates bile until needed by body.
When fatty foods digested, bile released by gallbladder.

25. In the Large intestine…
Regulation of H2O balance by absorbing large quantities back into bloodstream
absorbs Vitamin B complex and K
Bacterial action on digested food-decomposed products excreted through colon-bacteria form moderate amounts of B complex and Vitamin K
Gas formation 1-3 pints/day, pass it through the rectum (flatulence) 14 times a day, bacteria produce gas

26. Large Intestine Chyme - semi-liquid food Approx 2” in diameter 5’ Long
AKA: colon
Cecum-lower right portion of large intestine
Appendix: blind sac attached to the cecum, no known function, finger like projection
Rectum- last portion of large intestine
Anus- external opening

27. Sigmoid colon
S shaped part of colon, which extends 7 to 8 inches as the rectum

28. Structures of the digestive system