Bio104 Lecture Outline - Digestive System 8/07

Bio104Lecture Outline - Digestive System 8/07

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

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:

filliform –

fungiform –

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

B. Anatomy

Esophageal hiatus

Upper esophageal sphincter

Lower esophageal sphincter

C. Histology

Mucosa

Submucosa

Muscular layer

Adventitia

Stomach

A. Functions

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

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

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:

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