Bio104
Bio104 Lecture Outline - Digestive System 1/07
Hole’s HAP [Chapters 17 & 18] L. Falkow, Course Coordinator
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
-
-
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
-
-
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
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
▪ stimulates
▪ initiates
Pharynx
A. Characteristics
▪
▪
▪ 3 divisions:
Nasopharynx
Oropharynx
Laryngopharynx
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
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 (
(
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 –
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
➢
➢
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
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
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
-
-
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
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
Digestion and Absorption
A. CHO digestion
B. Lipid Digestion
C. Protein Digestion
D. Water Absorption
Clinical Disorders
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