Digestive System Flashcards
What does the Digestive System Include?
- Gastrointestinal (GI) tract
- Tube from mouth to anus
- Acessory organs
- Teeth, tongue, salivary glands
- Pancreas
- Liver, gall bladder
Processes of Digestive system
- Ingestion
- Digestion
- Absorption
- Defecation
Ingestion
Food into oral cavity
Digestion
- Large molecules broken down into smaller molecules
- 2 Types:
- Mechanical
- Physical breakdown & motility
- E.g. chewing
- Chemical
- Enzymes and acid secretions
- Mechanical
Absorption
End products of digestion enter blood or lymph
Defecation
Elimination of undigested material
Oral Cavity & Pharynx
- Oral Cavity
- Salivary Glands
- Dentition (teeth)
- Oropharynx and Laryngopharynx
Oral Cavity
- Lined by a mucosa (mucous membrane) made of a stratified squamous epithelium and lamina propria
- Includes:
- Lips
- Cheeks
- Palate
- Hard Palate
- Soft Palate
- Tongue
Hard Palate
2 maxillae and 2 palatine bones
Soft Palate
- Posterior to hard palate
- Skeletal muscle
- Posterior projection is uvula which rises to close the nasopharynx when swallowing
Tongue
- Attached to hyoid bone
- Skeletal muscle
- Projections of mucosa = papillae (taste buds)
Salivary Glands
- 3 pairs:
- Parotid
- Submandibular
- Sublingual
- Saliva
- 99.5% water
- 0.5% solutes (e.g. enzymes)
Parotid
- Inferior and anterior to ears
- Mumps = inflammation of 1 or both parotids
Submandibular
Floor of mouth
Sublingual
Below tongue on floor of mouth
Dentition (teeth)
- In maxillae and mandible
- Child dentition
- Primary dentition - deciduous (“baby”) teeth
- Adult dentition
- Secondary dentition - permanent teeth
Child Teeth Classification (In each quadrant)
- Central Incisor → 1
- Lateral Incisor → 1
- Canine → 1
- Premolars → 0
- Molars → 2
- Total Teeth (= # in each quadrant x 4) → 20
Adult Teeth Classification (In each quadrant)
- Central Incisor → 1
- Lateral Incisor → 1
- Canine → 1
- Premolars → 2
- Molars → 3
- Total Teeth (= # in each quadrant x 4) → 32
Tooth Structure
- Crown
- Root
- Neck
- Periodontal Ligaments
- Root canal extends to pulp cavity
NOTE: dentin, enamel & cementum is similar to bone, but avascular
Crown
- Above the gum
- Dentin forms majority of tooth
- Enamel overlay is acellular, highly calcified - hard!
Root
Dentin with a cementum overlay
Neck
Enamel and cementum boundary (gums)
Periodontal Ligaments
Attach root to bones
Root Canal Extends to Pulp Cavity
Contains connective tissue, blood/lymph vessels, and nerves
Oropharynx and Laryngopharynx
Only muscularis externa (skeletal muscle) and stratified squamous epithelium
What are the 4 basic layers of the Gastrointestinal Tract?
- Mucosa
- Submucosa
- Muscularis externa
- Serosa or adventitia
Mucosa
- 3 layers:
- Epithelium with numerous goblet cells
- Lamina propria (areolar connective tissue)
- Muscularis mucosa
Epithelium with numerous goblet cells
- Stratified squamous:
- Esophagus, anal canal
- Simple Columnar:
- Stomach, small and large intestines, rectum
Lamina propria (areolar connective tissue)
Contains blood, lymph vessels, lymph nodules/tissues (immune)
Muscularis mucosa
Smooth muscle - allows movement of mucosa
Submucosa
- Areolar CT
- Contains: blood, lymphatic vessels, and a network of nerve cells
Muscularis externa
- Two layers of smooth muscle separated by a second network of nerve cells
- Inner circular layer (contraction constricts the lumen)
- Outer longitudinal layer (contraction shortens gut length)
- Contractions controlled by the nerve network cause motility (mixing and movement)
Serosa or adventitia
Serosa is a double walled membrane