1. The Digestive System and Body Metabolism
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2. The Digestive System and Body Metabolism
Digestion
Breakdown of ingested food
Absorption
Passage of nutrients into the blood
Metabolism
Production of cellular energy (ATP)
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3. Organs of the Digestive System
Two main groups
Alimentary canal – continuous coiled hollow tube – 26 feet long
Accessory digestive organs
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4. Organs of the Digestive System
Figure 14.1
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5. Organs of the Alimentary Canal
Mouth
Pharynx
Esophagus
Stomach
Small intestine
Large intestine
Anus
Slide 14.3
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6. Mouth & Saliva Mastication means the chewing of food
Mixture of mucus and fluids helps to form a food bolus
Initiation of swallowing by the tongue
Contains salivary amylase to begin starch digestion
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7. Mouth (Oral Cavity) Anatomy
Lips (labia) – protect the anterior opening
Cheeks – form the lateral walls
Hard palate – forms the anterior roof
Soft palate – forms the posterior roof
Uvula – fleshy projection of the soft palate
Figure 14.2a
Slide 14.4
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8. Mouth (Oral Cavity) Anatomy
Vestibule – space between lips externally and teeth and gums internally
Tongue – attached at hyoid and styloid processes of the skull, and by the lingual frenulum
Figure 14.2a
Slide 14.5
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9. Mouth (Oral Cavity) Anatomy
Tongue –
frenulum
filiform papillae
fungiform papillae
circumvallate papillae
foliate papillae
Figure 14.2a
Slide 14.5
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11. Copyright 2009, John Wiley & Sons, Inc.
The three major salivary glands- parotid, sublingual, and submandibular
Copyright 2009, John Wiley & Sons, Inc.

12. Classification of Teeth
Deciduous teeth (milk teeth): 20 that fall out from 6-12 yrs
Adult teeth: 32 (28 is typical) 4 wisdom teeth are often pulled
Incisors: 8 teeth for cutting
Canines
Premolars
Molars
Slide 14.36a
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13. Classification of Teeth
Figure 14.9
Slide 14.36b
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14. Enamel is the hardest substance in the body
Teeth are alive and have blood vessels and nerves
Gum disease can cause teeth to eventually fall out- So brush daily.

15. Structures of the mouth (oral cavity)
Copyright 2009, John Wiley & Sons, Inc.

16. Pharynx Function Serves as a passageway for air and food
4-5 inches long
Deglutition:
Slide 14.9
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17. Pharynx Anatomy Nasopharynx – not part of the digestive system
Oropharynx – posterior to oral cavity
Laryngopharynx – area before trachea and esophagus
Figure 14.2a
Slide 14.8
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18. Esophagus Runs from pharynx to stomach through the diaphragm
Conducts food by peristalsis (slow rhythmic squeezing)
What is reverse peristalsis?
Passageway for food only (respiratory system branches off after the pharynx)
Slide 14.10
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19. Stomach Anatomy Located on the left side of the abdominal cavity
Acidic: so basically bacteria free
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20. Stomach Anatomy Regions of the stomach
Cardiac region – near the heart
Fundus – top portion
Body – middle section
Pylorus – funnel-shaped terminal end
Rugae – internal folds of the mucosa
External regions
Lesser curvature
Greater curvature
Slide 14.15b
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21. Stomach Anatomy Food enters the stomach at the cardiac sphincter
Food empties into the small intestine at the pyloric sphincter
Slide 14.16a
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22. Stomach Anatomy Slide 14.17 Figure 14.4a
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23. Stomach Functions Acts as a storage tank for food
Absorbs: (Fats just sit there)
Water
Sugars (from Carbs) – enzymes
Proteins – enzymes
Alcohols
Slide 14.18
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24. Specialized Mucosa of the Stomach
– produce a sticky alkaline mucus
ulcer
– produce protein-digesting enzymes (pepsinogens)
– produce hydrochloric acid
Slide 14.19
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25. Structure of the Stomach Mucosa
Figure 14.4b, c
Slide 14.20b
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26. Stomach Functions Peristalsis-muscular contractions
Chemical breakdown of protein begins
Delivers chyme (processed food) to the small intestine
Slide 14.18
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27. 18-21 feet long “Dogs Just Itch!
Subdivisions of the Small Intestine
18-21 feet long “Dogs Just Itch!
Duodenum – about 1+ foot
Attached to the stomach; acidic
Curves around the head of the pancreas
Jejunum – roughly 8-9 ft
Attaches anteriorly to the duodenum
Ileum – about 6-12 ft?
Extends from jejunum to large intestine; neutral pH
Slide 14.22
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28. Villi of the Small Intestine
Fingerlike structures formed by the mucosa
Give the small intestine more surface area
Figure 14.7a
Slide 14.24
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29. Microvilli of the Small Intestine
Small projections of the plasma membrane
Found on absorptive cells
Muscular tube extending from the pyloric sphincter to the ileocecal valve
Suspended from the posterior abdominal wall by the mesentery
Figure 14.7c
Slide 14.25
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30. Structures Involved in Absorption of Nutrients
Absorptive cells
Blood capillaries
Lacteals (specialized lymphatic capillaries)
Figure 14.7b
Slide 14.26
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31. Small Intestine The body’s major digestive organ
Site of all nutrient absorption into the blood
Bile
Lots of enzymes to finish break down of proteins and carbs. Begins and ends break down of fats here.
Pancreatic juices
Slide 14.21
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32. Propulsion in the Small Intestine
Peristalsis is the major means of moving food
Segmental movements
Mix chyme with digestive juices
Aid in propelling food
Slide 14.60
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33. Processes of the Digestive System
Peristalsis – alternating waves of contraction
Segmentation – moving materials back and forth to aid in mixing
Figure 14.12
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34. Large Intestine
Larger in diameter, but shorter than the small intestine
Frames the internal abdomen
Slide 14.28
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35. Large Intestine Slide 14.28 Figure 14.8
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36. Structures of the Large Intestine
Cecum – saclike first part of the large intestine
Appendix
Accumulation of lymphatic tissue that sometimes becomes inflamed (appendicitis)
Hangs from the cecum
Slide 14.30a
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37. Structures of the Large Intestine
Colon
Ascending
Transverse
Descending
S-shaped sigmoidal
Rectum
Anus – external body opening
Slide 14.30b
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38. Functions of the Large Intestine
Does not participate in digestion of food
Absorption of water dissolved vitamins & minerals
Eliminates indigestible food from the body as feces
We lack the enzyme cellulase and cannot digest veggies and cellulose
We live in symbiosis with bacteria; half our fecal matter is bacteria
Slide 14.29
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39. Food Breakdown and Absorption in the Large Intestine
No digestive enzymes are produced
Cholera is a bacteria that:
Slide 14.61
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40. Propulsion in the Large Intestine
Sluggish peristalsis
Mass movements
Slow, powerful movements
Occur three to four times per day
Presence of feces in the rectum causes a defecation reflex
Internal anal sphincter is relaxed
Defecation occurs with relaxation of the voluntary (external) anal sphincter
Slide 14.62
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41. Accessory Digestive Organs
(Salivary glands)
(Teeth)
Pancreas
Liver
Gall bladder
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42. Liver Largest gland in the body
Located on the right side of the body under the diaphragm
Connected to the gall bladder via the common hepatic duct
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43. Role of the Liver in Metabolism
Several roles in digestion- makes bile
Detoxifies drugs and alcohol
Degrades hormones
Produce cholesterol, blood proteins (albumin and clotting proteins)
Plays a central role in metabolism
Slide 14.77
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44. Bile Produced by cells in the liver Composition Bile salts
Bile pigment (mostly bilirubin from the breakdown of hemoglobin)
Cholesterol, Phospholipids, Electrolytes
Slide 14.40
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45. Gall Bladder Sac found in hollow fossa of liver
Stores bile from the liver by way of the cystic duct
Bile is introduced into the duodenum in the presence of fatty food
Gallstones can cause blockages
Slide 14.41
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46. Pancreas
Produces a wide spectrum of digestive enzymes that break down all categories of food
Enzymes are secreted into the duodenum
Alkaline fluid introduced with enzymes neutralizes acidic chyme
Endocrine products of pancreas
Insulin
Glucagons
Slide 14.38
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47. Messentary Identified as organ in January of 2017
Its function is still largely unknown

48. Digestive processes

49. Processes of the Digestive System
Chemical Digestion
Enzymes chemically break down food molecules into their building blocks
Each major food group uses different enzymes
Carbohydrates are broken to simple sugars
Proteins are broken to amino acids
Fats are broken to fatty acids and alcohols
Slide 14.44
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50. Chemical Digestion in the Small Intestine
Source of enzymes that are mixed with chyme
Intestinal cells
Pancreas
Bile enters from the gall bladder
Slide 14.23a
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51. Control of Digestive Activity
Stimuli include:
Stretch of the organ
pH of the contents
Presence of breakdown products
Reflexes include:
Activation or inhibition of glandular secretions
Smooth muscle activity
Slide 14.47b
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52. Chemical Digestion in the Small Intestine
Figure 14.6
Slide 14.23b
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53. Processes of the Digestive System
Ingestion – getting food into the mouth
Propulsion – moving foods from one region of the digestive system to another
Slide 14.42a
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54. Processes of the Digestive System
Mechanical digestion
Mixing of food in the mouth by the tongue
Churning of food in the stomach
Segmentation in the small intestine
Slide 14.43
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55. Processes of the Digestive System
Figure 14.11
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56. Nutrition
Nutrient – substance used by body for growth, maintenance, and repair
Categories of nutrients
Water
Minerals: metabolic reactions
Carbohydrates: provide energy; simple sugars, starches, fiber- 4cal/gram
Lipids: energy, cell membranes– 9cal/gram
Proteins: muscle composition, growth & repair, amino acids; 4cal/gram
Vitamins: regulate body processes
Slide 14.63
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57. Body Energy Balance
Energy intake = total energy output (heat + work + energy storage)
Energy intake is liberated during food oxidation
Energy output
Heat is usually about 60%
Storage energy is in the form of fat or glycogen. A pound of fat= 3500 Calories
What is healthy? How do you drop a pound?
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