Bio 104 Digestive System

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13 Bio 104 Digestive System

Lecture Outline: 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. -

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 16 Bio 104 Digestive System

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

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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 18 Bio 104 Digestive System

Stomach

A. Functions 1.

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.

E. Gastric Activities  Gastric Absorption

 Mixing & emptying Chyme =

Rate of emptying:

 Enterogastric reflex

F. Hormones

Gastrin –

CCK (cholecystokinin) –

Secretin – 20 Bio 104 Digestive System

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 

 21 Bio 104 Digestive System

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 22 Bio 104 Digestive System

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 23 Bio 104 Digestive System

C. Histology 1. Plicae circulares

2. Mucosa Intestinal villi –

mucosa  plicae  villi  epithelium  brush border ------> (increases surface area 600 times)

Each villus contains: a)

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

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Life Span Changes

Clinical Disorders

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