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Bio 104 Digestive System
Hole’s HAP [Chapters 17 & 18]
General Characteristics of the Alimentary Canal
A. Functions
1. Ingestion 2. Mechanical digestion 3. Chemical digestion 4. Propulsion 5. Absorption 6. Defecation B. Components of Digestive system
1. Alimentary canal (GI tract) -
2. Accessory organs -
C. Alimentary canal wall
1. Mucosa
a.
b.
c.
2. Submucosa
3. Muscular layer
-
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4. Serosa
- serous membrane
-
adventitia
D. Movements of the Tube


E. Innervation of the Tube
 Submucosal plexus
 Myenteric plexus
 Parasympathetic
 Sympathetic
Mouth
A. Functions




B. Parts of the Mouth
1. Cheeks and lips
-
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2. Tongue
- papillae:
o filliform –
o fungiform –
o circumvallate - lingual fenulum
ankyloglossia
3. Palate
Hard palate -
Soft palate Uvula
4. Tonsils
- palatine
- lingual
- pharyngeal
5. Teeth
Enamel –
Dentin –
Pulp cavity
Dentition formula: 3 2 1 4 1 2 3
Molars
Premolars
Canines
Incisors
Secondary teeth
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6. Salivary glands
- 3 pairs:
a. Parotid
b. Submandibular
c. Sublingual
- secretions of the salivary glands:
a. Parotid
b. Submandibular
c. Sublingual
- Saliva
a. Components

 electrolytes, buffers, glucoproteins,
enzymes, wastes

b. Functions
 moistens
Pharynx
A. Characteristics



3 divisions:
Nasopharynx
Oropharynx
Laryngopharynx

stimulates

initiates
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B. Swallowing Mechanism
 Soft palate, uvula, hyoid, larynx ___________

Epiglottis ____________ and closes off top of trachea

Muscles:
- longitudinal muscle
- inferior constrictor muscles

Peristaltic waves
C. Deglutition
bolus =
1. Buccal
2. Pharyngeal
3. Esophageal
Esophagus
A. Function
o
o
B. Anatomy
Esophageal hiatus
Upper esophageal sphincter
Lower esophageal sphincter
C. Histology
Mucosa
Submucosa
Muscular layer
Adventitia
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Stomach
A. Functions
1.
2.
3.
4.
B. Anatomy
Features
4 regions:
rugae:
C. Gastric secretions
1. pepsinogen
2. pepsin
3. hydrochloric acid
4. mucus
5. intrinsic factor
Gastric pits:
Gastric glands:
a) mucous cells 
b) chief cells 

c) parietal cells 

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D. Phases and regulation of gastric secretions
 Phases
1. Cephalic
2. Gastric
3. Intestinal
 Regulation of gastric secretions
1.
2.
3.
4.
E. Gastric Activities
 Gastric Absorption
 Mixing & emptying
Chyme =
Rate of emptying:
 Enterogastric reflex
F. Hormones
Gastrin –
CCK (cholecystokinin) –
Secretin –
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Accessory Organs: Pancreas, Liver, and Gallbladder
Pancreas
A. Structure:
head –
body tail –
pancreatic duct (Wirsung)
hepatopancreatic ampulla
hepatopancreatic sphincter
B. Histology
1. Pancreatic acini 2. Pancreatic islets (Langerhans)
a) Alpha cells  _________
BG levels
b) Beta cells  __________
BG levels
C. Pancreatic Juice
pancreatic amylase –
pancreatic lipase –
trypsin, chymotrypsin, and carboxypeptidase nucleases –
bicarbonate ions –
D. Regulation of secretions


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Liver
A. Anatomy
Lobes –
Ligaments –
Hepatic lobules –
Hepatic cells –
Hepatic sinusoids
Kupffer cells
Central veins
B. Bile ducts and bile
Bile ducts:
_____________  ____________  right & left _____________
 ___________ hepatic duct
Composition of Bile:
water
bile salts
o
o
bile pigments
cholesterol
electrolytes
C. Liver Functions
1) CHO
2) Lipid
3) Protein
4) Storage
5) Removal
6) Detoxification
7) Synthesis
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Gallbladder
Regulation of bile release:
Stores and concentrates bile
- releases bile --> cystic duct
- stimulated by CCK
between meals: hepatopancreatic sphincter
around duodenal ampulla closes
after a meal: CCK is released
 gall bladder to contract
 relaxes hepatopancreatic sphincter
Small Intestine
A. Divisions: Duodenum, Jejunum, Ileum
Duodenum
Jejunum
Ileum
B. Membranes
1. Peritoneum
parietal
visceral
retroperitoneal
2. Mesentery
3. Omenta
Lesser Omentum
Greater Omentum
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C. Histology
1. Plicae circulares
2. Mucosa
Intestinal villi –
mucosa  plicae  villi  epithelium  brush border
--------------------------------------------------------------->
(increases surface area 600 times)
Each villus contains:
a)
b)
3. Submucosa
4. Muscular layer
5. Serosa
D. Enzymes
peptidase –
sucrase, maltase, lactase
lipase – breaks down _______  _____________ + __________
enterokinase – converts ___________ to ____________
E. Hormones
CCK
Secretin
-
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F. Regulation of Intestinal Secretions



G. Absorption in the Small Intestine
 monosaccharides
 electrolytes
 fatty acids and glycerol
H. Movements in the S.I.
• mixing movements
• peristalsis –
• segmentation –
• overdistended wall triggers peristaltic rush resulting in
__________
Large Intestine
[cecum, ascending, transverse, descending,
sigmoid colon; rectum, anus]
A. Cecum
ileocecal valve –
vermiform appendix - vestigial part
B. Anatomical features
haustra diverticula taenia coli epiploic appendages ascending, transverse, descending, sigmoid colon
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C. Rectum
- last 15 cm of GI tract
- rectal columns
- anus (anal orifice): terminal 2-3 cm
- internal anal sphincter
- external anal sphincter
D. Large Intestine Wall
Mucosa
- lack of villi
- lots of goblet cells
- intestinal glands
Submucosa
Muscular Layer
Serosa
E. Functions of the Large Intestine
-little or no digestive function
-absorbs water and electrolytes
-secretes mucus
-houses intestinal flora
-forms feces
-carries out defecation
G. Movements of L.I.
H. Feces
- water, electrolytes, mucus
- bacteria
Color: bile pigments altered by bacteria
Odor - produced by bacterial compounds
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Digestion and Absorption
A. CHO digestion
B. Lipid Digestion
C. Protein Digestion
D. Water Absorption
Life Span Changes
Clinical Disorders