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24 Cards in this Set
- Front
- Back
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General Function of Digestive Tract
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Function: digestion, barrier (prevent pathogens from entering with the food)
Components: - oral cavity, teeth, tongue - liver, gallbladder - large intestine, small intestine - salivary glands - pharynx, esophagus - stomach, pancreas |
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Generalized Digestive Tract: Four Main Layers (digestion and hormone production)
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1. Mucosa- epithelial lining; lamina propria (loose CT); muscularis musosae (thin muscular layer)
2. Submucosa- consisting of dense irregular CT. Submucosal nerve plexus (the function of the submucosa is for support) 3. Muscularis- the main muscle function; two layers (circular and longitudinal) of smooth muscle; myenteri nerve plexus 4. Serosa- furthest outside; a serous membrane consisting of a simple squamous epithelium, the mesothelium, and a small amount of underlying CT. |
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Oral Cavity- Two Subdivisions
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* Two Subdivisions:
1. Vestibule- space between the lips, cheeks and teeth 2. Cavity- lies behind the teeth and is bounded by the hard and soft palates superiorly, the tongue and the floor of the mouth inferiorly, and the entrance to the oropharynx posteriorly. |
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Components of the Oral Cavity
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- lips
- cheeks - gums - tongue - palate - teeth |
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Oral Cavity- three types of mucosa
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1. Masticatory mucosa- found on the gingiva (gums) and hard palate. It is keratinized and, in some places, a parakeratinized stratified squamous epithelium (the nuclei are still there and highly condensed).
2. Lining Mucosa- found on the lips, cheeks, alveolar mucosal surface, floor of the mouth, inferior surfaces of the tongue, and soft palate. Non-keratinized, prone to movement (it has fewer and shorter papillae so that it can adjust to the movement of the underlying muscles) 3. Specialized Mucosa- associated with the sensation of taste and is restricted to the dorsal surface of the tongue. It contains papillae and taste buds responsible for generating the chemical sensation of taste. |
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Lips- components
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* Cutaneous- thin, keratinized, hair
* Red- thick, keratinized, papillae * Oral Mucosa- thick, parakeratinized (nuclei associated) |
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Cheek and Gum
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* Cheeks:
- nonkeratinized - dense lamina propria and submucosa * Gums: - keratinized - lamina propria bound to periosteum and periodontal - lack submucosa or glands |
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Palatine
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* Hard Palate:
- Masticatory mucosa - Submucosa along midline * Soft Palate: - lining mucosa - nonkeratinized - skeletal muscle associated- allows some voluntary control |
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Salivary Glands
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* Parotid glands (by ears):
- temporal region - duct at 2nd moral - 25% of saliva comes from here * Submandibular gland (back part of mouth): - submandibular triangle - duct at lingual frenulum - 70% of saliva comes from here * Sublingual: - Sublingual folds - numerous ducts - very little saliva comes from here |
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Tongue
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* Muscle Mass:
- striated - 3 layers, bundles (the muscle is arranged in bundles that generally run in three planes) - connected lamina propria * Mucous Membrane: - smooth underside - irregular dorsal surface: papillae lymphoid aggregates |
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Four Types of Papillae
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1. Filiform- across surface of tongue, increase friction, curve shaped, point backward. smallest and most numerous.
2. Foliate- aren't as well developed in humans. Tastebuds located on top. occur on the lateral edge of the tongue. 3. Fungiform- mushroom shaped; near tip of tongue. tend to be more numerous near the tip of the tongue, taste buds are present here. 4. Circumvallate- huge dome-shaped ones; form distinct dots in a V-shape. Human tongue has 8-12 of these. |
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Taste Buds
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- they form a barrel-shaped structure with a pore opening
- four tastes (sweet, sour, salty, bitter) * Cell Types: - Taste - Supportive - Basal * Sensation * Familial dysautonomia * Umami- represents the taste of certain amino acids (MSG) |
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Teeth
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* Crown (the exposed area above the gum line):
- Enamel- acellular; 95% mineralized tissue, hardest substance in your body *Root: - Alveoli (the socket where the root of the tooth fits into) - Cementum (thin layer of bone-like calcified tissue covering the dentin of the root of the teeth) *Cervix (neck) *Dentin- also acellular; a calcified material that forms most of the tooth substance. It lies deep to the enamel and cementum. * Pulp cavity- space within a tooth that is occupied by dental pulp (loose CT that is vascularized and nerves present) * Periodontal ligament (fibrous CT joining the tooth to its surrounding bone) *Gingiva (commonly called the gums)- soft epithelium (the tissue in between teeth) |
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Contents of the pulp cavity
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- Central Chamber
- Apical Foramen(where the blood vessels and nerves enter the pulp cavity at the tip of the root) |
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Esophagus Layers
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a tube for food transporting
Four Layers: - mucosa (protection, absorption, secretion) - submucosa (consists of a dense irregular CT layer containing blood and lymphatic vessels, a nerve plexus, and occasional glands) - muscularis externa (two layers- circular and longitudinal) - serosa (the outermost layer consisting of mesothelium) |
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Esophagus
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- upper portion is striated, middle is a mix, and lower is smooth muscle
*Mucosa: - nonkeratinized - esophageal cardiac gland (secretes a mucus; located in lamina propria) * Submucosa: - esophageal glands (secrete) *Muscularis: - inner = circular - outer = longitudinal *Serosa (reduced in upper portion and more prominent in lower portion) |
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Esophagus- Stomach Junction
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- an abrupt switch occurs
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Stomach
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- a mixed exocrine (releases into ducts)- endocrine (releases it on a surface) organ
- function: digestion *Digestion: - carbohydrates (amylase) - proteins (pepsin) - triglyceride (lipases) - form Chyme (a mush of everything in the stomach) * Rugae- lateral folds in walls of stomach- allow it to expand |
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Four Regions of the Stomach
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- Cardia
- Fundus - Body - Pylorus |
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Stomach Mucosa
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- Epithelium: simple columnar (secrete alkaline mucus to protect it from digestive enzymes); gastric pits (extend down into the lamina propria)
- Lamina Propria (loose CT): muscularis mucosae (separates lamina propria from underlying submucosa) |
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Fundus (body)
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- fundus and body are histologically the same
*Gastric Glands: - Parietal Cells - Chief Cells - Mucous Neck - enteroendocrine- hormone producing cells Neck of Fundus: parietal cells (HCl); Mucous Base: chief cells (make pepsinogen); enteroendocrine cells A collection of stem cells is also present that makes more of these cells |
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Parietal Cells
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take up CO2 from blood --> bicarbonate and proton made --> proton goes outside of cell and bicarbonate
K and Cl ions outside of cell Proton and Cl make HCl |
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Chief Cells
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- Lower region of glands= basal portion
- Pepsinogen (makes pepsin which digests proteins) - Lipase - granules associated with chief cells - nuclei, Golgi present |
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Pylorus
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- deep gastric pits (longest pits- secrete mucus and make lysozyme)
- pyloric glands - Gastrin cells- in pyloric glands; hormone-producing glands (produce gastrin) |
