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80 Cards in this Set

  • Front
  • Back
what are the four layers of the GI tract wall?
(from esophagus-->anal canal)
1. mucosa
2. submucosa
3. muscularis externa
4. serosa
what type of epithelium surrounds the mouth, pharynx, esophagus, and anal canal?
what three components make up the epithelial wall of the stomach?
1. simple columnar
2. exocrine cells
3. enteroendocrine cells
what role does simple columnar play in the stomach?
absorption with transport mechanism and secretory process
what role does exocrine cells play in the stomach epithelium?
mucous for protection and serous fluid for movement and action of enzymes (absorption)
what role do enteroendocrine cells play in the stomach epithelium?
secrete hormones into the blood
what does the epithelium of the lamina propia (CT) consist of?
1. blood and lymph vessels
2. MALT- mucosa associated lymphatic tissue
what organs are part of MALT?
"pyers patches", tonsils, and appendix
what is the muscularis mucosa?
a thin layer of smooth muscle
what are the 3 functions of the muscularis mucosa?
1. increase surface area for secretion and absorption
2, folding in stomach
3. larger role: muscle tone of lumen itself
what 4 components make up the submucosa of the GI tract?
1. areolar CT
2. blood and lymphatic vessels
3. submucosal plexus
4. glands and lymphatic tissue
what is the submucosal plexus?
extensive network of neurons (plexus of meissner)
what does the submucosa do?
controls the secretion of the glans
what is the muscularis externa dominated by?
smooth muscle
what 4 components make up the muscularis externa?
1. innter circular sheet
2. myenteric plexus
3. outer longitudinal sheet
4. skii muscles mixed with smooth muscle in muscularis externa
what does the myenteric plexus do?
controls contraction of muscularis externa
where will you see serosa?
in visceral abdominal cavity
what does the serosa do?
serous membrane that secretes serous fluid
what is serosa also called?
visceral peritoneum
what is the serosa consist of?
CT and simple squamos epithelium
what three organs lack serosa?
pharynx, esophagus, and rectum
what is adventitia?
outermost covering on digestive organs outside of the abdominal cavity; just CT
what is the enteric nervous system?
brain of our gut; esophagus-->anus
what are the 2 plexuses of the enteric nervous system?
1. submucosal
2. myenteric
what three type of neurons are within these plexuses?
1. motor neurons
2. sensory neurons
3. interneurons
what do motor neurons do?
-supply myenteric- controls motility
-supply submucosa- controls secretory cells (associated with glands)
what 2 types of sensory receptors are in the mucosal epithelium of the plexuses?
chemoreceptors and stretch receptors
what do interneurons do?
-connect myenteric and submucosal plexus
-CNS and ANS ties/modifies (interneuron connections)
what are the two types of neural controls within the digestive system?
1. extrinsic control
2. intrinsic ENS control
what 6 things that extrinsic control does?
1. enteric system triggers small, sight, sound, and taste
2. direct motor control by CNS--> start things up to ENS
3. modification by ANS
4. affect of emotions
5. we get muscle contractions
6. salivary glands
what 5 types of neurons are involved in intrinsic ENS control?
1. sensory neurons recieve signals from lumen going to ENS
2. motor neurons that drive smooth muscle
3. interneurons important for local reflexes
4. parasympathetic neurons
5. sympathetic neurons
what do motor neurons involve?
-drive smooth muscle
-submucosal and myenteric plexus
-secretions and contractions
what are interneurons important for?
local reflexes; they ONLY connect submucosal plexus to myenteric plexus within GI tract (staying local)
what do sympathetic neurons do?
shuts enteric down
what two type of hormones are involved in hormonal control of the digestive system?
1. peptide hormones
2. endocrine hormones
what type of cells are involved with peptide hormones?
enteroendocrine cells
what are 3 functions of peptide hormones?
1. released into CT and then blood vessels
2. enhance of inhibit muscle contraction
3. control secretion of gland cells release due to binding
what five components are part of the endocrine hormones?
peptide hormones, insulin, glucagon, PTH, and calcitonin
what are local mechanisms?
chemicals in interstitial fluid that effect small areas
how do the chemicals coordinate and 2 examples?
in response to changing conditions

1. prostaglandins- fatty acids secreted that affect metabolic activities
2. histamine- initiates/enhances inflammatory response; initiate secretion of acids
what are the oral or buccal cavity accessory digestive organs?
teeth and tongue
what 3 components are involves in the tongue?
1. extrinsic muscles
2. intrinsic muscles
3. lamina propria
what do the extrinsic muscles do?
move food from side to side, in and out, back to front
what do the intrinsic muscles do?
reshape tongue to form words and swallowing
what 2 things does the lamina propria contain?
1. papillae-tastebuds
2. lingual glands
what do lingual glands do?
secrete mucousy, serous fluid containing lingual lipase (begins digestion of triglycerides)
what is enamel?
-hardest substance in the body
-protection again bacteria acids
what are 2 functions of enamel?
1. protects the tooth from wear and tear of chewing
2. protects against acids that easily dissolve dentin which forms majority of tooth
what is mastication?
chewing, mov food around, saliva, and teeth
what is the result of mastication?
bolus (lump)
what runs how much saliva we need?
the CNS and cerebral cortex
why is mouth moist?
to decrease bacteria
what are 2 functions of the salivary glands?
1. saliva keeps mouth and pharynx moist
2. secretions increase when food arrives
how do the small salivary glands of mouth and toungue mucous membrane open?
directly or through ducts to oral cavity
what are the four ducts to oral cavity?
labial, buccal, palatal, and lingual glands
what are the 3 major salivary glands and where are they located?
1. parotid glands-serous
2. submandibular glands- mixed
3. sublingual glands- mucous
why is majority of saliva water?
because its a medium for dissolving food
what are the 7 types of solutes in saliva?
1. ions- chloride, phosphate, bicarbonate
2. glycoproteins
3. Antibodies
4. enzymes
6. wastes
what do bicarbonate and phosphate ions do?
buffer acidic foods
what do glycoproteins do?
mucous, aids in formation of bolus
what do Antibodies- IgA do?
prevents invasion
what do enzymes do?
lysozyme; salivary amylase; kills bacteria
what are wastes and what do they do?
urea and uric acid; they rid of blood from digestive system
what are the 3 phases of deglutition?
1. buccal phase
2. pharyngeal phase
3. esophageal phase
what happens during the buccal phase of deglutition?
-bolus is forced into oropharynx (back of throat with tongue)
-voluntary stage
what happens during the pharyngeal phase?
bolus stimulates receptors in oropharynx, swallowing reflex begins
what are the 4 steps of the pharyngeal phase?
1. impulses sent to deglutition center in medulla oblagata
2. bolus moves through oropharynx and laryngopharynx
3. respiratory centers inhibited
4. esophageal sphincter reflexes to push bolus through
what does the uvula and soft palate do?
lift up to block off nasopharynx
what does the epiglottis do?
closes the larynx
what happens during the esophageal phase?
bolus enter esophagus and is pushed toward the stomache
-long fibers-shorten, diameter widens
what are the three components of the esophagus's histology?
1. smooth muscle in the muscularis mucosae
2. mucous glands in submucosa moisten food
3. muscularis externa- circular and longitudinal
what are the three divisions of the muscularis externa of the esophagus?
1. Superior 1/3: skeletal muscle, voluntary
2. Middle 1/3: mixed smooth and skeletal, voluntary and involuntary
3. Inferior 1/3: smooth muscle only, involuntary
during esophageal phase of deglutition, what is the bolus being pushed by?
peristalsis which is a progression of coordinated contractions and relacations of circular and longitudinal muscle layers pushing food down (shorten and lengthen; wave-like)
what happens during peristalsis?
-circular muscles superior to bolus contract
-longitudinal fibers inferior to bolus contract
-controlled by neurons in myenteric plexus
-contractions repeated in waves
when does the esophageal sphincter relax?
-as bolus reaches end of esophagus
-bolus moves into stomach
what are the three steps of the esophangeal phase?
1. bolus pushed by peristalsis
2. lower esophageal sphincter relaxes as bolus reaches end of esophagus
3. bolus moves into stomach
what are the four main regions of the stomach?
1. cardia
2. fundus
3. body
4 pyloris
what is rugae?
mucosal folds for expansion
what is the pyloric sphincter??
-connection to duodenum
-control release of chyme
-regulated depending on chemical in area
what is the main/majority region of the stomach