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6541969 11 digestive system

6541969 11 digestive system

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DIGESTIVE SYSTEM

FUNCTIONS

1. Ingestion

2. Mastication

3. Propulsion

4. Mixing

5. Secretion

6. Digestion

7. Absorption

8. Elimination

HISTOLOGY OF DIGESTIVE TRACT

1) Mucosa - innermost tunic, consists of three layers.

a) Mucosa epithelium, stratified squamous epithelium

b) Lamina propria, loose connective tissue.

c) Muscularis mucosae, outer thin smooth muscle.

2) Submucosa – thick connective tissue layer containing nerves blood vessels and small glands.

3) Muscularis – inner layer of circular smooth muscle and an outer layer of longitudinal smooth muscle.

a) Exceptions superior esophagus has striated muscle, and the stomach has three muscular layers.

4) Serosa or Adventitia – connective tissue.

ORAL CAVITY

STRUCTURE

FUNCTION

Lips & Cheeks

Lips

Mastication, speech, & entrance

Frenula

Mucosal folds attach upper lip to alveolar process of the maxilla, and

from the alveolar process of the mandible to lower lip.

Cheeks

Mastication ,speech, & facial expression

Palate

Palate (hard & soft)

Mastication, soft palate prevents food from entering nasal cavity.

Tongue

Movement of food in mouth for mastication, swallowing, taste, speech.

Intrinsic muscles

Flattening and elevating tongue for swallowing.

Extrinsic muscles

Protrude and retract, side to side, and shape change.

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Teeth

Mastication and speech

Incisors

Cutting or nipping off food

Canines

Tear and pierce

Premolars

Grinding and crushing

Molars

Grinding and crushing

Salivary glands

Structure

Location

Parotid glands

Just anterior to the ear, bilaterally.

Submandibular glands

Inferior border of the posterior mandible

Sublingual glands

Immediately below the mucus membrane in the floor of the mouth

Saliva

• Secretion rate 1 to 1.5L/day

• Salivary amylase – serous saliva breaks down apart glucose molecules in starch and other

polysaccharides into disaccharides.

• Prevents bacterial infection together with lysozyme

• Mucin – proteoglycan that gives saliva a lubricating quality.

• Stimulated primarily by the parasympathetics and less by sympathetics.

ESOPHAGUS

Anatomy

• Approx. 25 cm.

• Between pharynx and stomach

• Located in the mediastinum anterior to vertebrae and posterior to trachea.

• Esophageal hiatus – opening in diaphragm and ends at stomach.

• 4 tunics, mucosa, submucosa, muscularis, and adventitia.

• Upper esophageal and Lower esophageal sphincter – regulate the movement of materials into and

out of esophagus.

Histology

• Mucosa stratified squamous epithelium with mucous glands that secret a thick lubricating mucus.

STOMACH

Anatomy

• Enlarged segment in left superior part of abdomen.

• Gastroesophageal opening (cardiac) – opening of stomach from esophagus.

• Cardiac region – located around the cardiac opening

• Fundus – left and superior to the cardiac region.

• Body – largest part of stomach curves to the right forming the greater and lesser curvature.

• Pyloric region – region where body narrows

• Pyloric opening - joins to the small intestine.

• Pyloric sphincter – thick smooth muscle surrounding the pyloric opening.

Histology

• Serosa – visceral peritoneum, outer most layer.

• Muscularis – three layers, longitudinal layer, circular layer, and an inner oblique layer.

• Rugae – large folds of submucosa and mucosa, allows stomach to stretch.

• Stomach is lined with simple columnar cells, with tube like gastric pits, which are openings for

the gastric glands.

• Surface mucous cells – produce mucus on the surface and lines the gastric pit.

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DIGESTIVE SYSTEM FUNCTIONS 1. Ingestion 2. Mastication 3. Propulsion 4. Mixing 5. Secretion 6. Digestion 7. Absorption 8. Elimination HISTOLOGY OF DIGESTIVE TRACT 1) Mucosa - innermost tunic, consists of three layers. a) Mucosa epithelium, stratified squamous epithelium b) Lamina propria, loose connective tissue. c) Muscularis mucosae, outer thin smooth muscle. 2) Submucosa – thick connective tissue layer containing nerves blood vessels and small glands. 3) Muscularis – inner layer of circular smooth muscle and an outer layer of longitudinal smooth muscle. a) Exceptions superior esophagus has striated muscle, and the stomach has three muscular layers. 4) Serosa or Adventitia – connective tissue. ORAL CAVITY STRUCTURE Lips & Cheeks Lips Frenula Cheeks Palate Palate (hard & soft) Tongue Intrinsic muscles Extrinsic muscles FUNCTION Mastication, speech, & entrance Mucosal folds attach upper lip to alveolar process of the maxilla, and from the alveolar process of the mandible to lower lip. Mastication ,speech, & facial expression Mastication, soft palate prevents food from entering nasal cavity. Movement of food in mouth for mastication, swallowing, taste, speech. Flattening and elevating tongue for swallowing. Protrude and retract, side to side, and shape change. Teeth Incisors Canines Premolars Molars Mastication and speech Cutting or nipping off food Tear and pierce Grinding and crushing Grinding and crushing Salivary glands Structure Parotid glands Submandibular gl ...
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