1. The Digestive System and Body Metabolism14
The Digestive System and Body Metabolism

2. CH 14 THE DIGESTIVE SYSTEM
I. Overview Of The Digestive System:
Functions
B. Major Processes
Ingestion
Digestion
Absorption
Defecation
C. Organs
Alimentary Canal
Accessory Digestive Organs
Sphincters

3. Mouth (oral cavity)
Parotid gland
Tongue
Sublingual gland
Salivary glands
Submandibular
gland
Pharynx
Esophagus
Stomach
Pancreas
(Spleen)
Liver
Gallbladder
colon
Transverse
Duodenum
Descending
colon
Small intestine
Jejunum
lleum
Ascending
colon
Large intestine
Cecum
Sigmoid colon
Rectum
Appendix
Anus
Anal canal
Figure 14.1

4. II. Organs of the Digestive System A. Alimentary Canal Organs. 1
II. Organs of the Digestive System A. Alimentary Canal Organs 1. Mouth (Oral Cavity)
a. Anatomy
Oral cavity proper—area contained by the teeth
Uvula—fleshy projection of the soft palate
- Function
Tongue
Tonsils

5. Nasopharynx Hard palate Soft palate Oral cavity Uvula Lips (labia)
Palatine tonsil
Vestibule
Lingual tonsil
Oropharynx
Lingual
frenulum
Epiglottis
Tongue
Laryngopharynx
Hyoid bone
Esophagus
Trachea
(a)
Figure 14.2a

6. iv) Chemical Digestion:
b. Mouth Physiology
i) Mastication:
Mixing with saliva
ii) Swallowing:
iii) Taste
iv) Chemical Digestion:
Enzyme:
Amylase + Starch Glucose + Glucose …

7. 2. Pharynx a. Anatomy: see Respiratory System iAnatomy– see Ch 13
Nasopharynx
Hard
palate
Soft palate
Oral
cavity
Uvula
Lips (labia)
Palatine tonsil
Vestibule
Lingual tonsil
Oropharynx
Lingual
frenulum
Epiglottis
Tongue
Laryngopharynx
Hyoid bone
Esophagus
Trachea
(a)

8. b. Pharynx Physiology passageway for air and food to Esophagus
How keep food out of Lungs– see Respiratory system-Larynx

9. 3. Esophagus
Anatomy
b. Location:
c. Functions

10. 4. Stomach a. Anatomy Shape Smooth muscle in Walls– 3 layers
Cardioesophageal Sphincter
4. Stomach a. Anatomy
Shape
Smooth muscle in Walls– 3 layers
Rugae—internal folds of the mucosa
can hold 4 L (1 gallon)
Inner Tissue (lining):
Microscopic- Gastric Glands
Location:
Sphincters
Cardioesophageal
Pyloric
Pyloric Sphincter
Rugae
Gastric Glands

11. Cardioesophageal sphincter Fundus Esophagus Muscularis externa Serosa
• Longitudinal layer
• Circular layer
Body
• Oblique layer
Lesser
curvature
Rugae of
mucosa
Pylorus
Greater
curvature
Duodenum
Pyloric
Sphincter
(valve)
Pyloric
antrum
(a)
Figure 14.4a

12. Fundus Body Rugae of mucosa Pyloric (b) Pyloric sphincter antrum
Figure 14.4b

13. Diaphragm Lesser omentum Liver Pancreas Duodenum Stomach
Visceral peritoneum
Transverse
colon
Greater omentum
Mesenteries
Parietal peritoneum
Small intestine
Peritoneal
cavity
Uterus
Rectum
Anus
Urinary bladder
(b)
Figure 14.5b

14. b. Stomach Physiology i) Temporary storage ii) Digestion of Proteins
Gastric glands— secrete gastric juice which contains:
- Hydrochloric Acid (HCl): produced by Parietal cells
- Pepsinogen: inactive form of enzyme; produced by Chief cells
Pepsin: activated form of enzyme Pepsinogen; activated by HCl
Chief Cells
Parietal
Cells
Pepsinogen
Gastric Glands
Pepsin
HCl

15. Pepsin digests Proteins into its subunits, Amino Acids
Pepsin + Proteins Amino Acids + A.A. …

16. 5. Small Intestine a. Anatomy i) Gross
Gross View
a. Anatomy
i) Gross
(1) Shape: Tubular; ??? Long, ?? wide
(2) Smooth Muscle: two layer
(3) Inner folds
Function
ii) Microscopic Anatomy
(1) Tissue of Lining:
(2) Villi:
Blood vessels
Lacteal
Microvilli
Microscopic view of Villi
Microvilli

17. Lumen Villi (a) Small intestine
Blood vessels
serving the small
intestine
Lumen
Muscle
layers
Circular folds
(plicae circulares)
Villi
(a) Small intestine
Figure 14.7a

18. Lacteal Villus (b) Villi
Absorptive
cells
Lacteal
Villus
Blood
capillaries
Lymphoid
tissue
Intestinal
crypt
Muscularis
mucosae
Venule
Lymphatic vessel
Submucosa
(b) Villi
Figure 14.7b

19. Microvilli
(brush border)
(c) Absorptive
cells
Figure 14.7c

20. b. Subdivisions of the Small Intestine
i) Duodenum
location
- Curves around
Receives substances from
Pancreas:
Pancreatic Duct
- Liver:
ii) Jejunum
iii) Ileum

21. c. Physiology-Functions
Chemical Digestion
Absorption
i) Chemical digestion
Enzymes for all nutrient types:
- Intestinal cells
- Pancreas
Nutrients– broken down into:
- Carbohydrates 
- Proteis 
- Fats 
- Nucleic Acids are broken down into 

22. ii) Emulsification of lipids with Bile:
iii) Absorption of Nutrients
Subunits absorbed by cells lining intestine.
- Then into capillaries
- Fat components via Lacteal
The Hepatic Portal Artery takes blood with nutrients to Liver for detoxification. Only afterwards does the blood go back to Heart.

23. Bile duct and sphincter Accessory pancreatic duct
Right and left
hepatic ducts
from liver
Cystic duct
Common hepatic duct
Bile duct and sphincter
Accessory pancreatic duct
Pancreas
Gallbladder
Jejunum
Duodenal
papilla
Hepatopancreatic
ampulla and sphincter
Main pancreatic duct and sphincter
Duodenum
Figure 14.6

24. Goblet cells produce mucus for ________ b. Subdivisions: Cecum
6. Large Intestine
a. ANATOMY
Larger diameter
Extends to anus
No villi present
Goblet cells produce mucus for ________
b. Subdivisions:
Cecum
Appendix
Colon
Rectum
Anal canal

25. Large Intestine Anatomy …
i) Appendix
lymphatic tissue that sometimes becomes inflamed (appendicitis)
ii) Colon
Ascending
Transverse
Descending—travels down the left side
Sigmoid
iii) Anus—inferior opening

26. External anal sphincter
Left colic
(splenic) flexure
Transverse
mesocolon
Right colic
(hepatic) flexure
Transverse colon
Haustrum
Descending colon
Ascending colon
IIeum (cut)
Cut edge of
mesentery
IIeocecal valve
Teniae coli
Sigmoid colon
Cecum
Appendix
Rectum
Alan canal
External anal sphincter
Figure 14.8

27. Large Intestine Physiology
c. Physiology– FUNCTIONS
Digestive enzymes:
Resident bacteria:
Produce:
Release gases
Absorption of:
Formation & Elimination of Feces

28. B. Accessory Digestive OrgansTeeth
1. Salivary Glands
Saliva composition:
Mucus and serous fluids
salivary amylase:
Functions

29. Bile duct and sphincter Accessory pancreatic duct
Right and left
hepatic ducts
from liver
Cystic duct
Common hepatic duct
Bile duct and sphincter
Accessory pancreatic duct
Pancreas
Gallbladder
Jejunum
Duodenal
papilla
Hepatopancreatic
ampulla and sphincter
Main pancreatic duct and sphincter
Duodenum
Figure 14.6

30. Location: Digestive products: secreted into: Hormones Function:
2. Pancreas
Location:
Digestive products:
secreted into:
Hormones Function:
Insulin:
Glucagon:
Duodenum
Pancreas

31. 3. Liver Location: Connected to: Lobes Produces BILE:
Bile salts & Pigments
Cholesterol
Phospholipids
Electrolytes
Depositied in:
Function
Liver
Pancreas
Gallbladder

32. Diaphragm Falciform ligament Liver Spleen Gallbladder Stomach
Greater omentum
Small intestine
Large intestine
Cecum
(a)
Figure 14.5a

33. 4. Gallbladder
Sac under liver
Function:
Bile released when:

34. III. Functions of the Digestive System-- Summarization
A. Ingestion:
Propulsion
Peristalsis
Segmentation—
B. Mechanical digestion
Teeth
tongue
stomach

35. Functions of the Digestive System
C. Chemical digestion
Mouth,
Stomach,
Small Intestine
D. Absorption
Most Nutrients:
Water: small and large intestine
E. Defecation =
Rectum & Anus

36. IV. Nutrition A. Introduction 1. Nutrients from food are used for:
Build molecules, cells, and structures
Replace worn out parts
Produce metabolic Fuels: ATP for energy
2. Kilocalories (kcal): unit of measurement of energy value of food
Nutrition– 6 categories of nutrients
1. Major nutrients
Carbohydrates
Lipids
Protein
Water

37. Minor Nutrients
Vitamins
Minerals
Five Food Groups
Grains
Fruits
Vegetables
Meats & Fish
Milk products

38. C. Dietary Sources of the Major Nutrients
1. Carbohydrates
a. Most from plants
Sugars: fruits & sugar cane
Starch: Grains, Legumes, Root vegetables
Cellulose
b. Lactose from milk
c. glycogens from meats
2. Lipids
a. Triglycerides (fats) are mostly the lipid in our food
Saturated fats: animal products & coconut
Unsaturated fats: plants as seeds, nuts, vegetable oils
Trans fats: “hydrogenated”

39. Proteins b. Cholesterol: egg yolk, meats, & milk products
2. Lipids …
b. Cholesterol: egg yolk, meats, & milk products
Proteins
a. Complete Proteins
Animal Products
Essential amino acids: 8 amino acids we can not make
b. Incomplete proteins
Plants: cereals, nuts, &
legumes
Are low in one or
more essential amino acids
Must eat combinations of
different types:
Example: cereal grains & legumes– rice & beans
Corn & Beans

40. D. Dietary Sources of Minor Nutrients
Vitamins
Must eat Combinations: No one food has all of the required vitamins
Cancer: Some protect against cancer (anti-oxidants)
Crucifer Vegetables: Broccoli, Cabbage, Brussel Sprouts: Vitamins A and C
Coenzymes: Function with Enzymes to complete chemical reactions
Minerals
Are components of Proteins, Hormones, Enzymes and Vitamins
Examples: 1) Iron in Hemoglobin attaches to the O2
2) Iodine is a component of Thyroid Hormone

41. V. Metabolism Carbohydrates mainly used to make ATP Glucose:
a. Blood Sugar = Glucose
b. Carbohydrate Digestion: Major breakdown product
c. Cellular Respiration: Major fuel used for making ATP; requires O2
Blood Sugar Homeostasis: Insulin & Glucagon
i) Hyperglycemia
First stored as glycogen in liver and muscles
Then converted to fat
ii) Hypoglycemia
Liver: breaks down glycogen into glucose
Fats: can be used to generate ATP

42. Fats mainly used to make other required lipid
Liver used them to synthesize Lipoproteins, Clotting Proteins, & Cholesterol
Fats also released into blood by Liver: Then cells take fats inside and make:
Cell membranes (phospholipids)
Steroid hormones
Myelin sheath of neurons
Fatty cushions around certain organs, like heart
Excess amounts stored as Adipose connective tissue: Equal amounts of glucose and fats, fats yield twice as much energy

43. C. Protein Metabolism
Liver processes digestive products before they circulate to the body; uses amino acids to make plasma proteins …
Cells use active transport processes to take amino acids inside (requires ATP)
They must have all 8 essential amino acids and the 12 others that cells can make in order to make any type of protein
Amino Acids used to produce ATP: Only under extreme conditions, like starvation
The nitrogen-containing portion is converted to Ammonia, which is toxic to neurons
Liver converts Ammonia into Urea which is removed in the urine

44. END