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135 Cards in this Set
- Front
- Back
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What are the two organ groups? What is their common embryo origin?
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1. Tubular organs and compact organs
2. The lining epi of the tubular organs and compact organs is endoderm |
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The 10 functional features of the digestive system
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1. Ingestion
2. Mastication 3. Deglutition 4. Secretion 5. Mixing and propulsion - motility 6. Digestion in the lumen (mechanic and chemical) 7. Absorption 8. Defecation of feces 9. Endocrine organs 10. GALT immunne defense |
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Define the alimentary canal?
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Esophagus, stomach, small intestine, large intestine
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Characterize most tubular organs. How is the alimentary canal different?
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Most tubular organs have three layers: (in to out) Mucosa - Muscularis Externa - Adventitia. The alimentary canal has a 4th layer called the Submucosa between the Mucosa and the Muscularis Externa
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How long is the alimentary canal?
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9 meters
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The three layers of alimentary mucosa
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1. Epi - strat squam or simple column
2. Lamina Propria - GALT immune system, vasculature 3. Muscularis Mucosae - smooth muscle in 2 layers. Outer is long, inner is circle. Move mucosa. |
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Contents of mucosa epi
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Exocrine goblet cells, Endocrine DNES
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Characterize the submucosa
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Type I collagen fibroelastic
GALT Largest vessels Location of the submucosal plexus of Meissner part of ENS |
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Control of Meissner's plexus
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Parasym - regulates mucosal motility and secretion
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Where in the alimentary canal are there glands in the submucosa?
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Esophagus and duodenum ONLY
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Where is there skeletal muscle in the Muscularis Externa? Smooth muscle?
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From lips to first .25 of esophagus, and then again at the external sphincter. Everywhere else is smooth muscle
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What is the function of the Muscularis Externa?
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Peristalsis
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How are the two muscle layers arranged in the muscularis externa?
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Inner circular, outer longitudinal. BOTH ARE HELICES
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Where is the myenteric plexus of Auerbach?
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Between the inner circle and outer long muscle layers of the muscularis externa
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What is the Adventitia of the alimentary canal?
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Thin collagenous layer that holds organ in place.
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What replaces the adventitia periodically?
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mesothelium, and therefore the adventitia *becomes* a serosa.
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Define intraperitoneal organ
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Covered in a fold of serosa
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Define retroperitoneal organ
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Behind a covering of serosa
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The three types of mucosae in the oral cavity. Locations and epi type.
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1. Lining mucosa: everywhere the others are not. Strat, squam nonkeratin
2. Masticatory mucosa: gingiva and hard palate 3. Specialized mucosa: dorsal tongue, strat squam non and parakeritanized. |
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Anterior boundary of the oral cavity? Posterior?
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Lips, palatoglossal folds
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The skeletal muscle mainly responsible for lip movement
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The orbicularis oris
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The three regions of the lips
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External aspect, vermillion border, internal mucosa
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Characteristic of the external lips
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Same as thin skin.
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What gives the lips their color?
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The numerous capillary beds under the translucent vermillion border
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What is missing from the internal mucosa of the lips
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No muscularis mucosae, just strat squam nonk and LP
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Fauces
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Opening between oral cavity and oropharynx
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Vestibule
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The space between cheeks and teeth.
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Characterize and define the parts of the tongue
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Mucosa (no sub or musc on dorsum) with LP invested in dense skeletal muscle. Anterior 2/3 is body, post 1/3 is root. The intrinsic muscles change the tongue's shape, the extrinsic move it around and out of the mouth.
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What CN ennervates the muscles of the tongue?
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CN XII
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3 types of lingual papillae
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Filiform, fungiform, vallate
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Innervation to the filiform papillae
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CN V -- Therefore, you know sinc it's the trigeminal nerve, they have no taste reception.
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Epi of the filiform papillae
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Parakeritinized
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Characterize fungiform papillae
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mushroom-like, 5 taste buds on plateau surface, strat squam nonk, appear red due to blood vessels
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Innervation to the fungiform papillae
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CN VII
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Characterize the vallate papillae
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The V line of visible nodes along the line between ant and post tongue. 100-300 taste buds on crypt surface, strat squam nonk
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Von Ebner's glands
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Crypt gland of the vallate papillae, secrete lingual lipase/wash chemical stimulae off the taste buds
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Where are the taste buds?
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Entirely in the epi of the tongue, small openings call taste pores lead into the epi layer to the specialized taste cells. Some are also on soft palate/pharynx/larynx/epiglottis
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What is hyposmia?
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A reduced ability to smell, and therefore taste
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4 types of gustatory receptor cells
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I: basal stem cells
II/III/IV: Specialized neuroepi with synapses to nerves, microvilli at apical border. |
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Time for total turnaround of taste buds
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1.5 weeks.
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5 detectable tastes into taste cells
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1. Salty - Sodium
2. Sour - Proton channel 3. Sweet - g-protein 4. Bitter - G-protein (gustducin) 5. Umami - Savory g-protein |
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Why do we smell food more than we taste it?
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There are thousands of times more smell receptors than there are taste.
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Innervation to fungiform taste cells. Vallate? Throat/epiglottis?
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CN VII
CN IX CN X if present |
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Where are the lingual glands? Name the three kinds
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Deep in the lamina propria
1. Anterior - mucous/serous demilunes 2. Posterior - Mucousal 3. Von Ebner's - Serous |
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What is important to remember about mixed mucous/serous glands?
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Each secretory product has it's own, DISTINCT duct system
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How many adult teeth and what are they?
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32: 8 incisors, 4 canines, 8 premolars, 12 molars
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How many deciduous teeth and what are they?
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20 - the teeth that fall out when you're a kid
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Dentin
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Neural Crest CT
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Enamel
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Hard mineralized covering of dentin, made from ectoderm
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Categorize and subcategorize enamel
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Anatomical crown -> neck and clinical crown
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What covers the root of the tooth?
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Cementum. Mesodermal mineralized CT.
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How are enamel, dentin and cementum similar? How are they different?
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All three are avascular. Enamel does not contain collagen.
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Dentin is made by whom?
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Odontoblasts.
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Support for tooth
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PDL - dense fibrous CT, suspend tooth by Sharpey's fibers. Very sensitive.
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Alveolus
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Tooth socket
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Gingiva
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Strat squam paraker, dips into gingiva sulcus.
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Dentin
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Collagen and calcium, made from neural-crest odontoblasts, grows by apposition all through life.
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Enamel
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Hardest material in body, apatite crystals, produced before eruption by ameloblasts. ENAMEL CAN NOT BE REFORMED.
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Cementum
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Mesodermal cementocytes in lacunae, covers root dentin avascularly, can be reformed throughout life.
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Hard palate
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Ant 2/3 of upper mouth. Nasal side is respiratory mucosa, oral side is mucoperiosteum -> palatine
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Soft Palate
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Post 1/3 of upper mouth. Muscular core. Moves to block nasopharynx from food. Strat squam nonk epi.
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Uvula
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Weird little soft palate "tongue " at back of mouth.
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Characteristics of parakeritinized epi
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No stratum granulosum and the surface cells are alive.
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The three major salivary glands of the mouth
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parotid, submandibular, sublingual
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Characteristics of parotid gland
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Serous, branched acinar, intercalcated ducts, fat cells, derived from ECTODERM, CN IX
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Characteristics of Submandibular gland
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Make 70% of saliva, mixed mucoserous but mostly serous, artifactual serous demilunes, striated ducts. MAKE EPI GROWTH FACTOR. Wide lumen. Endodermal. CN VII
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Characteristics of Sublingual glands
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Mixed mucoserous, mostly mucous, no intercalcated ducts, almost no salivary volume. Endodermal. CN VII
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The three common names of the parotid, submandibular, and sublingual ducts, respectively
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Stensen's, Wharton's, Rivinus
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2 kinds of exocrine intralobular ducts and their characteristics
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1. Intercalcated: lead directly from acini/tubules. SIMPLE CUBOIDAL EPI
2. Striated: infoldings, SIMPLE COLUMNAR EPI |
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How much saliva is made in a day?
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1000 mL.
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What is unique about salivary gland innervation?
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It's autonomic but the parasym and sym systems are not antagonistic. Parasym greatly increases secretions, watery. Sym only moderately, but a lot more viscous.
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Composition of saliva
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99% water.
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Aldosterone effect on saliva
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Made more hypotonic in striated ducts as Na is reabsorbed.
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Begins carbohydrate digestion in mouth
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Salivary amylase
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Composition of salivary antibacterial component. KNOW
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1. IgA, lactoferrin, lysozyme
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Members of the upper digestive tract
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Oropharynx, laryngopharynx, esophagus
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Lining of the oropharynx and laryngopharynx, esophagus
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strat squamous epi
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3 types of tonsils
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Lingual, pharyngeal, palatine tonsils
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The immunodefenders of the esophagus
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Langerhann's cells, degrade antigens to epitopes, MHC-II carry epitopes to lymph nodes and pass off to lymphocytes
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How many layers does the muscularis mucosae have in the esophagus?
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1
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Name of the glands in the submucosa of esophagus? In the lamina propria?
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1. Esophageal glands proper
2. Esophageal cardiac glands |
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Characteristic of the muscularis externa in the esophagus, from top on down
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1/3 skeletal
1/3 mix 1/3 smooth ...just add garlic. just kidding |
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Outer covering of esophagus above the diaphragm? Below the diaphragm?
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Adventitia. Serous.
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Formation of esophageal varices?
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Blockage of the portal vein -> blood is rerouted through left gastric, then esophageal, then azygous -> Increased pressure can cause esophageal veins to swell.
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Two physiological sphincters of the esophagus
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1. pharyngoesophageal
2. gastroesophageal LATCH contractors |
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4 parts of the stomach
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Cardiac
Fundus Body Pyloric Antrum |
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Names of the entrance to the stomach. Name of the exit.
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Cardiac orifice.
Pyloric orifice. |
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Epi of the stomach
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Simple columnar mucous cells.
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Are there goblet cells in the stomach?
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No.
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What are the gastric pits?
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The entrance to the gastric glands.
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General characteristics of the gastric glands
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1. In lamina propria, across entire layer
2. Exocrine but no true duct |
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Why is the epi of the stomach called an epi sheet gland?
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The epi is in itself secretory, a gel-like mucous made of bicarbonate.
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What do cardiac and pyloric glands have in common?
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The length of the secretory unit and the gland is the same.
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Product of cardiac glands?
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Mucous
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Product of pyloric glands?
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Mucous, lysozyme, and hormones
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How many glands are in the fundus?
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15 million
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The three regions of a fundic gland secretory unit, from outside in
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Isthmus, neck, base
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5 cell types of the fundic gland
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Pluripotential, Mucous, Parietal, Chief, DNES
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Fundic stem cells
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Neck, Bidirectional migration, stimulated by gastrin and EGF
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Fundic mucous neck cells
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Soluble mucous
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Fundic parietal cells
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Neck/Base. Invaginations of plasma membrane called intracellular secretory canaliculus. Tubulovesicular system. THESE CELLS MAKE HCL
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Physiology of fundic parietal cells
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When making HCl, the tubulovesicular system vanishes and the ISC appear. Vice-versa.
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Appearance of the intracellular secretory canaliculus
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Crosshatch tubules
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Three main stimuli of acid production
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Gastrin (DNES), histamine (mast, DNES) and acetylcholine (para)
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Two main inhibitors of acid production
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Prostaglandins and somatostatin
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Why does ibuprofen cause stomach ulcers?
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The inhibition of prostaglandins results in no inhibition of HCl
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Gastrin Intrinsic Factor. Pathology?
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Required via binding for Vitamin B12 absorption in small intestine. Pernicious anemia.
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Chief cell contents and location.
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Pepsinogen in zymogen granules, gastric lipase. Found in base of fundic gland.
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Total content list of all gastric glands
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Water
HCL, GIF Pepsinogen, Gastric Lipase Protective mucous Soluble mucous. |
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The 5 gastrointestinal hormones and their function
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1. Secretin
2. Gastrin 3. CCK 4. Gastric Inhibitory Peptide 5. Motilin -Metabolic, Motility, Growth, Self-stimulation |
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What's weird about gastric DNES cells?
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Their secretory granules are in the basal cytoplasm.
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Catalysis of HCl production
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Carbonic anhydrase stimulates proton generation in the cytoplasm from HCO3
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Serotonin - function/location
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inhibit acid, duodenum
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VIP - function, location
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Vasoactive intestinal peptide, secretion/absorption, GI tract
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Secretin - function, location
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Stimulate H20 and bicarbonate from pancreas - duodenum, jejunum
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CCK - function, location
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Bile release, Sphincter of Oddi relaxation - duodenum, jejunum
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GIP - identity, function, location
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Stimulates insulin release from beta cells in pancreas. Duodenum, jejunum. Gastric inhibitory peptide
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Motilin - function, location
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Stimulate gastric motility after meals - duodenum, jejunum
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Layers of the muscularis externa in the stomach
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Inner oblique, middle circular, outer longitudinal
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Where is the myenteric nerve plexus?
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Between the middle and outer layers of the stomach's muscularis externa
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What is the common mucosal barrier?
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Tight junctions and protective mucosa. So the stomach lining isn't eaten away by excess acid.
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Ghrelin
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Regulate metabolics during starvation. Causes hunger.
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Cephalic phase
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Gastric stimulation by psychological (parasym) effects
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Gastric phase
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Elicited by gastrin and histamine in response to actual food being in the stomach
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Intestinal phase
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Inhibitory influence on motility so that a regulated amount of chyme enters the duodenum.
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How long is the small intestine in a living person?
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3 meters
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Three regions of the small intestine
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Retroperitoneal duodenum, empty jejunum, twisted ileum
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General functions of the small intestine
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1. Digestion of chyme
2. Absorption of nutrients 3. Hormone production |
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3 modifications of the luminal small intestine surface to max absorption
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1. Permanent folds: plicae circularis
2. Villi - projections containing absorptive/goblet cells. 3. Striated border microvilli |
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Crypts of Leiberkuhn
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Intestinal glands in the lamina propria between villi projections in the small I. Contain stems cells for goblet, absorptive, DNES, Paneth
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4 epi cells of small intestine
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1. Absorptive cells
2. Goblet cells 3. DNES - 1% 4. M Cells - sample, phagocytose, transport antigens |
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Characteristics of S. intestine lamina propria
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1. GALT
2. Fenestrated capillaries 3. Lacteals (only in intestine) 4. Smooth muscle 5. Crypts of Leiberkuhn |
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Paneth cell
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Manufacture lysozyme, TNF-alpha, defensins: antibacterial
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Submucosal specialization of duodenum
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Brunner's glands - secrete alkali to neutralize the acidic chyme, and EGF
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Submucosal and LP specialization of ileum
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Peyer's Patches: lymphoid nodules - GALT
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