SM02 Mini2 Flashcards
what are the parts of the the digestive system?
- oral cavity
- tongue
- salivary glands
- esophagus
- stomach
- small intestine
- appendix
- large intestine
- rectum
- anus
- accessory: liver, gallbladder, & pancreas
apex of the sulcus terminalis?
foramen cecum
sulcus terminalis
v-shaped junction between 2 parts of tongue from different embryological origins
anterior oral two-thirds
posterior pharyngeal one-third
type of epithelium found on the dorsal aspect of the tongue
keratinized stratified squamous epithelium
except for parts of protruding papillae
type of epothelium found on ventral aspect of tongue
nonkeratinzed stratified epithelium
where in the digestive mucosa is the muscularis mucosa absent?
the tongue
what nerve controls the muscular layer of the tongue?
CN XII
Hypoglossal nerve
on right (top to bottom):
- palatine tonsil
- lingual tonsil
- palatoglossal arch & mucosa
- foramen cecum
- sulcus terminalis
- circumvallate papillae
- foliate papillae
- filliform papillae
- fungiform papillae
- median sulcus
features of filiform papillae
- heavily keratinized epithelium
- connective tissue core
- catch food
- give tongue sandpaper-like character
- most abundant type of papillae
- no taste buds
which papillae of the tongue do not have taste buds?
filiform papillae
features of fungiform papillae
- muschroom-shaped projections
- larger than filiform
- non-keratinzied or lightly keratinized stratified squamous epithelium
- taste buds on dorsal surface
features of circumvallate papillae
- largest papillae
- row across tongue 2/3 of the way posteriorly
- mushroom-shaped
- non-keratinized epithelium
- 250 taste buds/papilla
- located laterally, facing moat surrounding papilla’s base
- von Eber’s glands
what are von Ebner’s glands?
purely serous glands in association w/circumvallate papillae
secrete into circumvallate moat
stain dark
features of foliate papillae
- leaf-like
- found along the sides of the tongue
- rudimentary in humans
- absent in some individuals
where are the minor salivary glands found?
throughout submucosa: lips, cheeks, soft palate, & floor of oral cavity
what do the minor salivary glands secrete?
all seromucous glands
secreting mucus & serous fluids
what are the major salivary glands?
parotid, submandibular, & sublingual
how do the major salivary glands differ from the minor ones?
- secrete into oral cavity via excretory ducts
- surrounded by capsule of dense irregular collagenous connective tissue
- division into lobes & lobules by septa of connective tissue
- ductal system
what are myoepithelial cells?
muscle-like epithelia that surround sercretory acini of major salivary glands
what types of glandular cells are in the parotid gland?
purely serous cells
what types of glandular cells are in the submandibular gland?
mixed serous & mucous cells
predominantly serous secreting
distinctive demilunes
what types of glandular cells are in the sublingual gland?
mixed serous & mucous cells
predominantly mucous secreting
serous demilunes present
what are the histological difference found inthe ductal system of the major salivary glands?
in order from secretory cells to oral cavity:
- intercalated ducts: low cuboidal cells
- straited ducts: simple cuboidal w/basal striations
- interlobular/excretory ducts:w/in connective tissue septa of gland
what is the purpose of the basal striations of the striated ducts?
active transport of Na+ ions from saliva into extracellular space
4 layers of GI tube
- mucosa
- submucosa
- muscularis externa
- adventitia/serosa
what type of papillae is this?
filiform papilla
what type of papilla is this?
fungiform
what type of papilla is this?
circumvallate papilla
what is at the tip of the arrowhead?
von Ebner’s glands
what type of papilla is this?
foliate papilla
what type of gland is this?
Parotid
what gland is this from?
Parotid
what gland is this?
submandibular
what gland is this?
submandibular
what gland is this?
sublingual
what are the layers of the GI mucosa?
epithelium
lamina propria: loose connective tissue
muscularis mucosae: thin layer of smooth muscle (can be absent in some individuals)
what is found in the GI submucosa?
dense connective tissue layer
Meissner’s plexus (submucosal plxus)
**glands** only in esophagus & duodenum
where is Auerbach’s plexus found?
aka myenteric plexus
between the inner circular & outer longitudinal layers of muscle in the muscularis externa
how many muscles are found in the muscularis externa?
normally 2: inner circular layer & outer longitudinal layer
but stomach has a 3rd innermost layer in the oblique direction
what is the difference between serosa & adventitia?
- adventitia
- outermost layer is attached to surrounding tissue
- fibrous connective tissue arranged around organ that it supports
- serosa
- outermost layer lies adjacent to peritoneal cavity
- connective tissue w/surface of mesothelium
what type of epithelium is found in the esophagus?
stratified nonkeratinized squamous epithelium
what do the submucosal glands of the esophagus secrete?
mucus
where are cardiac glands found & what do they secrete?
mucus secreting glands of the esophagus
how can the muscularis externa layer differeniate which section of esophagus one is viewing?
- superior (oral) portion has only skeletal muscle
- middle portion has a mix of skeletal & smooth muscle
- inferior portion has only smooth muscle
where is the physiological sphincter?
at the junction between the esophagus & stomach
not a “real” sphincter b/c there is no morphological thickening of the inner circular layer of muscle
Is the eosphagus coasted by serosa or adeventita?
both
serosa in the peritoneal cavity & adeventitia above
what is this?
esophagus
what are the portective mechanisms of the esophagus?
- thick stratified squamous epithelium
- scattered lymphatic tissue
- mainly B cells
- antibodies present in lamina propria & submucosa
what is GERD?
gastro-esophageal-reflux-dz
stomach acid refluxes into esophagus
if esophageal mucusis no longer present for protection of the mucosa, then pathological condition
what is Barrett’s esophagus?
stratified squamous epithelium of esophagus is replaced by simple columnar epithelium of stomach
if congential→ok
if acquired→precancerous
**thus do not ignore chronic heartburn**
what type of mucosa is this?
normal, healthy esophageal mucosa
what type of mucosa is this?
Barrett’s esophagus
what type of epithelium is found in the stomach?
simple columnar
what are gastric pits?
invaginations of mucosa that terminate as gastric glands
glands vary in different regions of the stomach
how are the glands of the cardiac region of the stomach formed?
50/50 ratio of gastric pit to gland
deep, long, branched, & coiled
contain mucus-secreting cells, stem cells, & enteroendocrine cells
very few parietal cell present
how are the gastric pits of the pyloric region of the stomach characterized?
2/3 pit: 1/3 gland
deep pits
short, branched, coiled glands
predominantly mucus-secreting cells
also contain enteroendocrine, G cells, & D cells
what is the function of G cells?
to secrete gastrin
found deep in pyloric glands
what is the function of D cells?
to secrete somatostatin
can be found in stomach, intestine, & pancreatic islets
how are the gastric pits in the fundus & body of the stomach characterized?
1 shallow pits:5 deep glands
glands are straight
neck of glands contains: mucus cells, lot of parietal cells, & stem cells
base of glands contains: few parietal cells, chief cells, mucus cells, & enteroendocrine cells
what is the function of parietal cells?
production & secretion of HCl & intrinsic factor in the stomach
what is the function of chief cells?
production & secretion of pepsinogen in the stomach
where would this gastric pit be found in the stomach?
cardia
where would this gastric pit be found in the stomach?
pylorus
where would this gastric pit be found in the stomach?
body or fundus
what does a lack of intrinsic factor lead to?
gastric atrophy
pernicious anemia
*cannot absorb vitamin B12*
why are parietal cells more likely to be found in the upper half instead the lower half of gastric glands?
b/c acid secretions would destroy the mucosa if released from the lower half of the gland
what type of cell is this?
parietal cell
“fried egg” appearance
what type of cells are present?
black arrow: chief cells
larger cell: parietal cell
how is the appearance of Chief cells classified?
aka zymogenic/peptic cells
triangular shape
basally located nucleus
strongly basophilic (blue/purple)
what is the function of Chief cells?
produce & endocytose pepsinogen & a weak lipase
what type of cell is this?
Chief cell
what type of cell is this?
parietal cell
where are the enteroendocrine cells usually found?
at the base of glands in stomach
how do mucus neck & surface cells differ?
those on the surface secrete a more viscous type of mucus than those found in the neck of the gland
how often must the surface mucus cells of the stomach be renewed?
3-7 days
how are the cells of the stomach renewed?
stem cells at the neck of gastric glands mitotically divide & differentiate into different cell types
move in either direction depending on type of cell differentiated
surface mucus cells replaced 3-7 days
glandular cells are replaced over several weeks (less exposure to harsh stomach acid environment)
what type(s) of glands are found in the submucosa of the stomach?
none
what is unique about the muscularis externa of the stomach compared to the rest of the GI tube?
it has 3 muscles: inner oblique, middle circular, & outer longitudinal
what are the characteristic features of the small intestine mucosa?
villi/crypts
plicae circulares: transverse folds
what is shown in the picture?
small intestinal mucosa
red: villi
blue: plicae circulares
what cell types are found in the small intestinal mucosa?
- goblet cells
- columnar absorptive cells
- enteroendocrine cells
- paneth cells
- stem cells
where are/what are the crypts of Lieberkuhn?
aka cryptal region
found between vili of small intestines
stem, enteroendocrine, & paneth cells are found at their base
what creates the brush border?
microvilli coated w/glycocalyx
found on enteroctyes/absorptive cells
what is the function of APUD cells?
aka amine precursor uptake & decarboxylation
produce hormones (gastrin, somatostatin, cholecystokinin, secretin, etc) that enter circulation & modulate various activites of GI tract
what is the function of Paneth cells?
produce & secrete lysozyme
Brunner’s glands
tubuloacinar glands
found in submucosa of duodenum
secretes clear alkaline mucin (pH8.2-9.3) that empties into the neck of crypts→ protects mucosa from acidic chyme
creates optimal pH for pancreatic enzyme function
Peyer’s patches
aggregations of lymphatic tissue (GALT)
covered by M (microfold) cells
more prominent distally w/in the ileum
what are the parts of the small intestine?
- duodenum: 25cm
- jejunum: 2m
- ileum: 3.5m
how can the regions of the small intestine be differentiated?
- duodenum: contains Brunner’s glands & leaf-like villi
- ileum: contains Peyer’s patches & has finger-like villi
- jejunum: no Brunner’s glands or Peyer’s patches
what causes Celiac dz?
autoimmune disorder
genetically predisposed
ingestion of gluten leads to damage of villi in small intestine
affects 1:100 ppl worldwide
what types are cells are found in colorectal mucosa?
simple columnar epithelium: absorptive, globet, stem, & enteroendocrine cells
no villi
no plicae circulares
crypts present
what is unique about the muscularis externa of the colon?
outer longitudinal layer is divided into 3 strips
taeniae coli
where would this mucosa be found?
colon, rectum, or anus
how can the rectum be differentiated from the colon?
no taeniae coli
why does the histology of the anal canal change at the pectinate line?
b/c the anus has 2 different embryologicla origins
how does the epithelium change throughout the anal canal & anus?
upper 1/2: simple columnar
lower 1/2: stratified squamous non-keratinized
anus: stratifed squamous keratinized
list the accessory glands attached to the digestive tract & their attachements
- liver
- common hepatic duct→ common bile duct→ sphincter of Boyden→ hepatopancreatic ampulla of Vater→ sphincter of Oddi
- gallbladder
- cystic duct→ common bile duct→ sphincter of Boyden→ hepatopancreatic ampulla of Vater→ sphincter of Oddi
- pancreas
- pancreatic duct→ hepatopancreatic ampulla of Vater→ sphincter of Oddi
role of the liver in digestion
production & secretion of bile & transfer of IgA into bile canaliculi
role of gallbladder in digestion
storage & concentration of bile
functions of the liver
over 100
- endocrine functions: production & release of plasma proteins (albumin, lipoproteins, fibrinogen)
- storage & conversion of some vitamins (A & D)
- degradation of drugs & toxins by sER
- modification of hormone actions
- carbohydrate storage
- exocrine functions: production & release of bile and transfer of IgA into bile canaliculi
- phagocytosis by Kuppfer cells
why is 75% of blood to the liver deoxygenated?
- carrying
- nutrients & toxins from intestines
- blood cells & breakdown products from spleen
- hormones from pancreas
describe boundaries & contents of classic liver lobule
based off of pig microanatomy
six-sided polyhedron
surrounded by dense irregular connective tissue
composed of hexagonal mass of anastomosing plates of hepatocytes radiating around central vein & separated by hepatic sinusoids
portal triad at periphery: portal vein, hepatic artery, & bile duct
describe boundaries & contents of hepatic acinus
diamond shape w/2 central hepatic venules & 2 portal triads as the corners
this model is most frequently used by pathologists & physiologists
describe boundaries & contents of 3 zones of liver acinus
- zone 1
- central area of acinus
- closest to distributing veins & arterioles
- most oxygen &nurtrient rich
- zone 2
- around zone 1
- zone 3
- beyond zone 2
- connects to central hepatic venules
- most O2 & nutrient poor blood
why is hepatomegaly seen in heart failure?
during congestive heart failure, O2 levels in zone 3 of liver acinus is so low that necrosis of hepatocytes occurs
describe gallbladder structure
what is this?
how are liver lobules drained?
central vein of lobule is terminal hepatic venule
several connect to form a single sublobar vein
sublobar veins connect to for hepatic vein
where does lymph originate?
space of Mall between connective tissue & hepatocytes
where are the hepatic sinusoids and their purpose?
between anastomosing plates of hepatocytes
mixed blood from from portal triad to central hepatic venule
speciallized capillaries tha carry blood thru liver parenchyma
associated w/endothelial, kupffer, & ito cells
describe boundaries & contents of portal lobule
allows to describe liver as an exocrine gland
triangle formed by three central hepatic venules w/a portal triad in the center
what types of cells compose the liver parenchyma?
- hepatocytes
- kupffer cells
- Ito cells
compare & contrast the lateral & sinusoidal domains of hepatocytes.
- lateral domains
- form bile canaliculi that receives exocrine bile
- leakage prevented by tight junctions on either side of canaliculi
- gap junctions allow communication between hepatocytes
- sinusoidal domain
- have microvilli for exchange of materials w/blood
what type of endothelium is found in the hepatic sinusoids?
discontinuous sinusoids w/discontinuous basal lamina
large fenestrations w/o diaphragms
large gaps between endothelial cells
what is the function of Kupffer cells?
macrophages of liver
phagocytes
what is the function of ito cells?
store vitamin A w/in cytoplasmic lipid droplets
secret vitamin A as retinol
secrete type II collagen (reticular fibers) in the space of Disse (betwen hepatocytes & endothelial cells)
secrete growth factors for new hepatocytes
what causes liver cirrhosis?
hepatic cell injury triggering collagen fibrotic secretion (type I & III) by myofibroblasts derived form Ito cells in the liver
where is glycogen stored in the liver?
sER of hepatocytes
how do bile acids & bilirubin enter bile?
- bile acids
- reabsorbed by the intestines
- cholic acid conjugated w/taurine & glycine in sER
- secreted into bile canaliculus
- bilirubin
- from hemoglobin breakdown
- glucuronyltransferase conjugates water-insoluble bilirubin forming water-soluble bilirubin glucuronide
- bilirubin glucuronide secreted into bile canaliculus
describe the bile ductal system.
- bile canaliculi form continuous polygonal branching system w/in lobule
- canaliculi join bile ducts via short squamous canals of Hering
- R + L bile ducts join to form hepatic duct
what are the red arrows pointing at?
glycogen granules
what is the blue arrow pointing at?
bile canaliculus
what is stained black?
Kupffer cells
what is shown in the image?
section of gallbladder
mucosa, NO submucosa, muscularis externa, & serosa (excepts where is contacts the liver=adventitia)
what type of mucosa is found in the gallbladder?
simple columnar epithelium
lamina propria
NO muscularis mucosae
what are the arrows indicating?
short arrow is pointing to a glomerulus
long arrow is running the length of a medullary ray
what is a medullary ray?
group of straight collecting ducts in the middle of a renal lobule
medullary refers to their destination, not location
ducts of Bellini
large collecting ducts that open at renal papilla into minor calyx
formed by the fusion of many collecting tubules
what type of epithelium is found in the renal collecting system?
cuboidal in tubules but columnar in ducts
gradual change in height
what cells respond to ADH and how?
principal cells of collecting tubules & ducts by becoming more permeable to water
increasing water reabsorption
collecting tubules & ducts are made of what type of cells?
mostly principal cells, but also H+ secreting intercalated cells
they cannot be distinguished by H&E stain
what is a renal labyrinth?
cortical parenchyma that surrounds a medullary ray
what is the function of the primary cilium in the kidney?
responsible for detecting fluid composition & flow dynamics
associated with stretch activated ion channels in kidney tubules
flow-mediated deflection of cilia axoneme induces increased intracellular Ca2+ that alters gene expression
what is a primary cilium & how is it formed?
single rod-like organelle that extends into luminal extracellular environment
form on almost all cell types
many receptors are localized on its surface
composed of microtubules (as normal cilia) but non-motile due to lack of cental pair of microtubules 9+0
what occurs when primary cilia are defective?
ciliopathies
ex. polycystic kidney dz
polycystic kidney dz
- caused by defective proteins of primary cilium
- inhierited autosomal dominant or autosomal recessive
- 4th leading cause of kidney failure (5%)
- all races
- causes numerous fluid-filled cysts to grow in kidneys
- cysts slowly replace much of kidney→ reduced kidney function
- cells misinterpret defective primary cilium signal & dedifferentiate & proliferate
what structures are part of the excretory pathway?
minor & major calyces
ureters
bladder
urethra
what type of epithelium is found in the excretory pathway?
transitional epithelium
stratified cuboidal with dome-shaped cells on surface
how do the ureters deliver urine to the bladder?
peristaltic waves of smooth muscle contraction
what layers are found in the ureters?
mucosa=urothelium (transitional epithelium) +lamina propria
muscularis externa of smooth muscle layered in opposite orientation to that in GI wall
adeventitia of loose connective tissue w/autonomic nerves & plexuses
***same in bladder***
urine production pathway starting at glomerular capillary
- glomerulus
- Bowman’s space
- urinary pole
- proximal convoluted tubule
- proximal straight tubule (thick descending limb)
- thin descending limb of the loop of Henle
- thin ascending limb of the loop of Henle
- thick ascending limb of the loop of Henle
- distal convoulted tubule
- collecting duct
- papillary duct of Bellini
- area cribrosa
- minor calyx
- major calyx
- renal pelvis
- ureter
- urinary bladder
- urethra
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