Digestive System

stomach regions, contains?

cardiac - contains cardiac glands fundic - largest, contains fundic glands body (only anatomy) pyloric - proximal to pyloric sphincter, contains pyloric glands

Large intestine -regions -functions -general structure

cecum (+ veriform appendix), colon, rectm, anal canal -reabsorption of electrolytes and water, elimination of undigested food and waste -typical structure - mucosa, submucosa, muscularis externa, serosa/adventita

Large intestine regional differences

colon - largest part. Well expressed taeniae coli (not in appendix or rectum) veriform appendix - no important role in digestion or absorption, has a lot of aggregated lymphatic follicles Rectum - mucosa similar to distal colon, contains prominent Transverse Rectal Folds.

Plicae Circulares -contain -structure -location

contain mucosa and submucosa -transverse folds -distal duedenum, proximal jejunum, increase surface for absorption

Submucosa consists of what kind of tissue? What does it contain?

dense connective tissue Vascular plexus & submucosal nerve plexus (Meissner's plexus)

esophagus submucosa -tissue? -contains

dense irregular connective tissue -blood, lympphatic, nerve/ganglions (Meissner's/ submucosal Plexus) contains esophageal glands proper

STomach submucosa -tissue type -glands

dense irregular connective tissue No glands plexus of blood vessles, nerve plexus: meissner's (submucosal) plexus

small Intestinal adventita/ serosa

duodenum covered by adventitia jejunum, ileum by serosa

Mucosa faces the what and includes which components

faces the lumen includes lining epithelium, lamina propria, muscularis mucsae

Foliate papillae -location -shape -taste buds -other

few, sides of tongue, lateral ridges taste buds in grooves, von ebner's serous lingual salivary glads drain into grooves just like circumvallate papillae

Stomach functions -what's chyme?

food storage food digestion: HCL and enzymes (pepsin, lipase) - break down food into triglycerides/ proteins regulation of GI function (secretes hormones (gastrin) mix food with gastric juices = chyme

esophagus glands -where found? -types -secrete what?

found in mucosa and submucosa -mucosal glands - esophageal cardiac glands, terminal part of esophagus, sometimes begining -esophageal glands proper: in submucosa, small tubuloalveolar, along length of esophagus

Taste buds -where are they? -shape -staining? -characteristics? -Cells in taste bud?

fungiform, circumvallate, foliate papillae oval, pale-staining, usually extend into epithelium sensory and support cells, stimulation causes nerve impulse along postsynaptic sensory nerve

Large intestine serosa

has small fatty projections - omental appendices, visible on outer intestinal surface

Porgenitor cells

in isthmus of gland replace mucous cells and fundic gland cells (like parietal, mucous neck, chief, enteroendocrin cells) Short lifespan (3-5 days), cells within the fundic gland live longer (6-8 months) - which cells? enteroendocrine, mucous, gastic cheif, parietal?

Pyloric Glands -location -function

in pyloric antrum produce mucus that protects pyloric mucosa deep gastric pits, more than 1/2 muscoa

esophagus muscularis externa -layers -how differ from rest of GI?

inner circular and outer longitudinal layers -has skeletal muscle in some parts -upper 1/3 = skeletal muscle -middle 1/3 = skeletal and smooth muscle -lower 1/3 = smooth muscle

Gastric pits -formed by what -lined with what? -are they glands? -where loctated?

invaginations of surface epithelium lined with surface mucus cells stomach mucosa NOT glands

Peyer's patches

large groups of lymphoid follicles in the ileum large structures follicle-associated epithelium covering peyer's patches, mostly M-cells/

Stomach mucosa glands -located in which layer? -open into what? -types of gastric mucosal glands?

located in the lamina propria open into bottom of gastric pits fundic, cardiac, pyloric

Small intestine -characteristics -Regions -functions -general strucutre and layers *unique feature

longest part of alimentary cnal (over 6m) Regions: duodenum, jejunum, ileum principal site of digestion nutrient absorption synthesis and secretion of digestive enzymes microbial growth control in lumen regulate GI function via ndocrine secretion by enteroendocrine cells -mucosa, submucosa, muscularis externa, serosa/ adventitia *plicae circulares

Intestinal lamina propria -cell type -contains? -blood supply lymphatics

loose connective tissue -lymphoid follicles - form the GALT (gut-asscuated lymphoid tissue), immunolgoic barrier between intestinal lumen and body) -capillary loops, begin from artierioles, return to venules of plexus. Soluble nutrients (AA, carbs) transported by blood vessles -each villus has blind ended lymphatic capillary Lacteal

Stomach lamina propria

loost connective tissue between gastric pits/ glands immune system elements (lymphocytes, plasma cells, macrophages) if inflammation, neutrophils, eosinophils.

filiform papillae -function -location -taste buds? -other features

mechanical keratinized, points backwards no taste buds Over entire dorsal surface

Stomach Serosa

mesothelim with thin layer of subserosal connective tissue

Barrett's esophagus

metaplasia of esophageal lining (displacement with intestinal columnar epithelium). Usually from GERD, males over 50. Common precursor to esophageal adenocarcinoma

esophagus adventitia/ serosa -mostly what composed of what? Which part is different, how?

most is adventitia loose connective tissue blending into surrounding connective tissue very distal part in peritoneal cavity is serosa.

Layers

mucosa, submucosa, muscularis externa, serosa

Crypts of Lieberkuhn -2 types of cells found in crypts of lieberkuhn, not in surface epithelium

mucosal glands throughout intestine tubular glands invaginations of surface epithelium -paneth cells, progenitor cells.

Brunner's glands

mucus producing branched tubular most abundent in proximal duodenum highly alkaline secretions - protect intestinge by netralizing acid-containing chyme

Oral cavity minor salivary glands -secreation? -shape? -intrinsic or extrinsic? (located where?)

muscous-secreting, branched tubular, intrinsic within wall of oral cavity

Oral Cavity - does NOT have which layers?

muscularis externa, serosa/ adventitia

Fungiform papillae -shape -location -taste buds?

mushroom-shaped more on tip on tongue taste buds on apical surface

myoepithelial cells

non secretory, in acini contractile, basal part of secetory cells

Esophagus mucosa -epithelium -lamina propria -muscularis mucosae

non-keratinized stratified squamous epithelium loose connective tissue, less celluar than rest of GI longitudinally oriented smooth muscle, separated by connective tissue (rest is circularly oriented)

Oral cavity submucosa

not clearly separated from lamina propria. Contains submucosal glands (minor salivary glands)/

Small intestine lymphoma

on of most common cancer of small intestine from B or T-lympocyte in lamina propria wall of intestine becomes thickened, infiltrated by lympohocytes

Cell types in fundic glands

parietal, gastric cheif, mucous neck, enteroendocrine, progenitor

Major salivary glands main role & functions intrinsic or extrinsic?

parotid (in front/ below ear, largest, all serous), submadibular (floor of oral cavity, mixed mostly serous), sublingual (small, floor of oral cavity, mixed mostly mucous) -production of saliva -lubricate oral cavity, moisten food -digestive enzymes, start digestion of carbs -antibacterial effect - controls growth in oral cavity/ caries -immunological functions, contains immunoglobin A -Source of calcium and phosphate (for normal tooth development) -extrinsic

Parietal cells functions structure Clinical - loss of parietal cells?

produce HCL (starts protein digestion, converts pepsinogen to pepsin, kills bacteria) and Intrinsic factor (for intestine to absorb B12) -largest, "fried eggs," intracellular canaliculi, microvilli, lots of plasma membrane - apcial membrane of non-secreating cells is stored in Tubulovesicular system lots mitochondria -loss results in pernicious anemia b/c of intrinsic factor deficiency, so can't incorporate hem into hemoglobin molecule -gastric ulcer - if epithelial barrier in stomach is impaired, HCL destroys epithelial cells and cells of lamina propria -untreated, can penetrate gastric wall, stomach becomes perforated, gastric content pours into peritoneal cavity = perionitis

circumvallate papillae -shape -location -features

round, dome shaped back of tongue, 8-12 surrounded by moat-like groove grove epithelium is thinner, has taste buds von Ebner's serous salivary gland ducts empty into moats

Large intestine submucosa

same as rest of alimentary canal (dense connective tissue, mseissner's plexus

Intestinal Enteroendocrine cells

same as stomach -base of gland -secrete product into lamina propria -secrete gastrointestinal hormones, regulate alimentary canal function eg, gastrin -> gastric aci d secretion, ghrelin-> appetite, hunger perception small cells, rest on basement membrane, form microvilli that reach lumen, cells filled with secretory granules in basal part of cells, secrete into lamina propria

Major salivary gland structure 3 parts, components of each

secretory part, -three types of acini -serous -euchromatic nucleus in center of cell, basal cell is basophilic b/c lots RER, apical cell w/ small secretory granules, cells are usually pyramidal shape. Serous acini are spherical in shape. -mucous -heterochromatic nuclei basally placed, mucous secretory granules in central/ apical part of cell, stain light with H&E, usually columnar. Mucous acini are tubular -mixed (seromucous) -tubular mucous with serous cap (serous demilune) -myoepithial cells duct system -intralobular ducts -intercalated: from the secretory acini low/ simple cuboidal epithelium nucleus near base of ductal cells -striated: connect intercalated to interlobular ducts lined with simple columnar epithelium infoldings of basal plasma membrane lots of mitochondria absorption of ions -make saliva hypotonic (transport NaCl from saliva) nucleus in middle/ upper part of cell -interlobular ducts -lined wi/ statified columnar epithelium -Main ducts -lining is stratified squamous epithelium as approach oral cavity stroma

small Intestinal muscularis mucosae -composed of

several sheets of smooth msucle

Tubulovesicular system

where apical membrane of non-secreting cells stored when parietal cells stimulated to secrete HCL, tubovesicular system fuses with apical membrane, allows formation of microvilli in the intracellular canaliculus

Tongue -epithelium cell type -is it keratinized? Where? -contains intrinsic and extrinsic muscles (Define)

-stratified squamous epihtelium -often keratinized on dorsal surface -intrinsic origin/insertion in tongue -extrinsic origin outside, insertion in tongue

Oral cavity muscosa - components?

Epithelium (stratified squaous epithelium), lamina propria, NO muscularis mucosae. -non-keratinized in most of oral cavity, keratinized in hard palate, gingiva, some of tongue

M-Cells -function -cell structure

--antigen transport: take microorganisms from epithelial lumen to lymphoid follicles. Macromolecules are endocytosed, discharged in intercellular space near T-lymphoctyes -large, dome-shaped. basal surface is invaginated, forms large pocket, separated from intestinal lumen by apical cytoplasm. pcket filled with macrophages, dendritic cells, lymphocytes -covered by microfolds (NOT microvilli), trap microbes, macromolecules

How to identify regions of small intestine -duodenum -jejunum ileum

-Dudenum: submucosal Brunner's glands, least # of goblet cells. -Jejunum: tallest, villi, most prominent lacteals -ileum: Peyer's patches, highest concentration of goblet cells, villi are shorter than duodenum/ jejunum

Enteroendocrine cells -where -secrete product into what? -function

-base of gland -secrete product into lamina propria -secrete gastrointestinal hormones, regulate alimentary canal function eg, gastrin -> gastric aci d secretion, ghrelin-> appetite, hunger perception small cells, rest on basement membrane, form microvilli that reach lumen, cells filled with secretory granules in basal part of cells, secrete into lamina propria

Gastric cheif cells -location -main function -other characteristics

-base of the gland -seceation of pepsinogen - converted to proteolytic enzyme, pepsin -protein secreting abundent RER in basal part of cell basophilic appearance secretory granules in apical protion of cell

Paneth Cells -location -function -structure

-bottom of crypts of lieberkuhn -regulate bacterial growth -numerous large, refractile eosinophilic granules in apical protion of cell -contain antibacterial enzyme lysozyme, alha-defensins, etc. -kills some bacteria, sustain normal bacterial flora in intestine basal part of cell contains well-developed RER

Progenitor cells -location -function

-in crypts of Lieberkuhn -undifferentiated cells, replacement cells for surface epithelial cells, except intraepithelial lymphocytes,

Cardiac glands -location -function -structure

-narrow ring surrounding esophageal orifice -produce mucus for gastric juice, protects against acid reflux -branched tubular, mucus-secreting cells basally placed flattened nucleus, cytoplasm filled with mucinogen granules NO praietal or cheif cells Gastric pits not as deep as pyloric gastric pits (less than 1/2)

Mucous neck cells -location -main function

-neck of gland -secreate soluble mucous -small cells, heterochromatic nucleus, at base of cell, cytoplasm filled with mucinogen granules, "frothy"

Enterocytes/ intestinal absorptive cells -functions -structure -location

-nutrient absorption -produce digestive enzymes for final digestion (carb protein final stages in glycocalyx of the cells) -monoglycerides/ fatty acids from lipids diffuse accross absorptive cell membrane, syth into triglycerides in GOlgi, become chylomicra, released into extracellular space -transcytosis of IgA from lamina propria to lumen -> igA absorbed/ transported to enterocyte apex, released into lumen. IgA regulate microbrial growth. -tall columnar cells numerous microvilli on apical surface -> brush/striated border -Apical portion is bound by tight/ anchoring junctions = barrier between intestinal lumen and epithelial intercellular compartment. predominant cells in intestinal mucosal epithelium

Goblet cells -functions -cell structure

-prodcution of mucus -narrow base, wide apex -filled with mucinogen granules -frothy cytoplasm -very pale. nucleus is small, traingular, heterochromatic, located at cell base

large intestine muscularis externa

2 layers of smooth muscle inner circular, outer longitudinal -outer longitudinal forms three layers, equally spaced bands called teniae coli

Stomach Muscularis externa -layers

3 layers of smooth muscle -inner oblique -middle circular -out longitudinal -myenteric nerve plexus (Auerbach's plexus) between middle circular and longitudinal layers

lingual papillae

4 types (filiform, fungiform, circumvallate, foliate)

4 layers

Mucosa, sub mucosa, muscularis externa, serosa/ adventia

Large intestine mucosa

NO Villi mucosal epithelium is like small intestine -columnar intestinal absorptive cells (enterocytes) -NO paneth cells -goblet cells are more abundent than in small intestine - extensive mucus production, moves waste -crypts of lieburkhun, same cells as urface epitheliu,, deeper crypts also contain progenitor cells - precursors to epithelial cells -Adenocarcinoma: most common malignant tumor of large intestine. Usually colon or rectum. most common in patients with adenomatous polyps/ ulcerative colitis. TX = resection of colon

Muscularis Externa is composed of what kind of tissue? How organized? What does it contain?

Smooth muscle, skeletal (up 1/3 esophagus) mixed skeletal/smooth (middle 1/3 esophagus) -organized into two layers: inner circular, outer longitudinal -contains myenteric (Auerbach's) plexus

Intestinal intraepithelial lymphocytes Type of... Derived from... Provide...

T-lymphocyte Blood-derived provide mucosal immunity

lacteal

blind ended lymphatic capillary in lamina propria of small intestine villus -drain into larger lymphatic vessels in submucosa transport lipds as chylomicra produced by enterocytes -chylomicra are secreted into laminao propria by enterocytes, picked up. transported to larger lymphatic vessels by lacteals.

Fundic glands -shape -3 segments -location and course

brnached tubular, straight in middle, coiled at base everywhere except cardiac/pyloric , from muscularis 3 segments: isthmus (apical), neck (middle), base/fundis (bottom) adjacent to muscularis mucosae. mucosae to gastric pits

Digestive System consists of the alimentary canal (what?) and principal associated organs (what)

canal begins with: oral cavity (esophagus, stomach, small/large intestines), tongue, teeth, salivary glands, pancreas, and liver

Stomach muscularis mucosae -clinical - malignant tumors of gastric epithelium

sheet of smooth muscle with 2-3 thin layers orthogonal (circular and longitudinal) orientation -from surface epithelial cells, or from glandular epithelium early stage = no penetration into submucosa, late - into muscularis externa/ further

surface epithelium -epithelium type -cell type -> produce what? -apical portion filled with -forms what?

simple columnar epithelium surface mucus cells, produce INsoluble, thick, viscous, gel-like coat that adheres to epithelial surface, protects from chyme abrasion apical protion filled with mucinigen granules

Serosa. where in body?

simple squamous epithelium (mesothelium) coving thin underlying layer of connective tissue. In peritoneal cavity.

Adventitia

thin layer loose connective tissue, blends into connective tissue of surrounding structures

small Intestinal muscularis externa

tpical inner circular layer outer longitudinal layer nerve plexus (Auerbach's) between the two layers

small Intestinal submucosa

typical, consists of dense connective tissue contains vascular and nerve plexus (Miessner's) -contains submucosal glands in the duodenum (Brunner's glands)

salivary gland tumors -characteristics -most common type, made of what kinds of cells?

usually in major salivary glands, 80% benign, most common is pleomorphic adenoma (made of ductal and myoepithelial cells)

Stomach rugae

when stomach is empty, folds of submucosa/ mucosa - decrease in height as stomach expands