Week 1-Fri, 3/24/23-MA lec-Exocrines
enteroendocrine cells in duodenum release...
-cholecystokinin -secretin
differentiate formation of endocrine glands vs. exocrine glands
-endocrine glands: lose connection with covering epithelium; become highly vascularized -exocrine glands: maintain connection with covering epithelium; develop conducting portion of gland (duct); distal portion becomes secretory portion of gland; in both conducting (proximal) portion and secretory (distal) portion of gland, cells arrange themselves in 1-2 layers
what are goblet cells? where are they found?
-goblet cells = mucin-secreting unicellular glands (found in respiratory epithelium + intestinal mucosa)
understand image - serous and mucous cells in merocrine gland
-notice: apical portions, darkly stained secretory granules (ex of serous cells) -notice: mucous cells, outlined by thin rim of cytoplasm (but granules not as darkly stained as other ones) - doesn't stain well bc mucous cells have polysaccharide rich substance
compare major salivary glands: -parotid gland -submandibular gland -sublingual gland
-parotid gland -submandibular gland (mix of serous, mucous, and mixed) -sublingual gland
what are ex's of salivary glands?
-parotid salivary gland -sublingual salivary gland -submandibular salivary gland
merocrine secretion occurs where?
-salivary glands -exocrine pancreas
what are ex's of compound exocrine glands?
-salivary glands -exocrine pancreas
what are ex's of compound glands?
-salivary glands -pancreas
what happens w/ apocrine secretion?
-secretory product either accumulates in secretory vesicles OR in the form of liquid droplets -rather than undergoing exocytosis, entire apical portion of secretory cell is shed off into lumen "cell decapitation" --> apical portion pinches off
stroma consists of what?
-septum -capsule
what's ex of holocrine secretion?
-skin/sebaceous glands
what are main types of secretion?
1) merocrine 2) holocrine 3) apocrine
secretory portion of sweat glands has what type of cells?
1) pale/clear cells 2) dark cells 3) myoepithelial cells
what's on outside of compound glands?
CT capsule
secretin stimulates...
HCO3- secretion
what's diagnostic feature of pancreas?
Islets of Langerhans cells
does exocrine pancreas have myoepithelial cells?
NO
when you have mucous secretion, ducts will mostly be...
NOT striated
what are the most common tumors in adults, including colon, lung, and breast cancers?
adenocarcinomas, malignant tumors of glandular epithelia
understand apocrine secretion - histology
apical fragments containing lipid droplets, continuously shed off into the lumen
acinus = what?
berry
where are myoepithelial cells located?
between basal lamina and secretory or duct cells
besides digestive proenzymes, what is another secretory product of exocrine pancreas?
bicarb
parenchyma of exocrine glands consists of what?
both secretory and conducting portions of glands
"compound" gland means what?
branched
understand holocrine secretion - histology
cell lysis occurring in lumen of sebaceous glands
understand higher mag view of exocrine pancreas - what else can we see?
centroacinar cells (can see individual zymogen granules in apical portion of cell)
exocrine pancreas is example of...
compound acinar gland
parotid gland is what type?
compound acinar gland
sublingual gland is what type?
compound tubuloacinar gland
submandibular gland is what type?
compound tubuloacinar gland
for myoepithelial cells, what helps expel secretory product?
contraction
endocrine and exocrine glands develop from what?
covering epithelium
understand merocrine secretion - histology
darkly stained secretory granules in apical portions of cell membrane-bound vesicles that are electron dense
striations are so abundant that they...
displace nuclei to apical portions of cell
acidic chyme stimulates...
enteroendocrine cells in duodenum
what's pancreatitis?
enzyme-mediated inflammation
merocrine secretion is another word for...
exocytosis
mucus consists of what?
heavily glycosylated glycoproteins mucins
where are intralobular ducts located?
in lobules
acinus empties into...
intercalated duct
how to distinguish intercalated ducts from secretory units?
intercalated ducts do not have any secretory granules
intralobular ducts join together to form...
interlobular ducts
what's in septa?
interlobular ducts
intercalated ducts join together to form...
intralobular ducts
striated intralobular ducts in salivary glands are similar to what?
kidney tubule cells
what do myoepithelial cells possess?
long contractile actomyosin-rich processes
what's ex of apocrine secretion?
mammary glands
what's most common type of secretion?
merocrine
mucous cells secrete...
mucous
what's the size of intercalated ducts?
no more than 6 cells round
understand slide on myoepithelial cells
non-secreting cells, take on smooth muscle like characteristics
"simple" gland means what?
not branched
cholecystokinin stimulates...
proenzyme secretion
serous cells secrete...
protein
where are interlobular ducts?
run in septa of lobule
transcytosis is mechanism of...
sIgA secretion
what happens w/ holocrine secretion?
secretory product droplets accumulate in cell and then entire cell ruptures, releasing contents into lumen (whatever was inside cell becomes secretory product)
describe merocrine secretion
secretory product is packaged into membrane bound vesicle (secretory vesicle or granule) - this fuses with apical membrane of plasma cell via exocytosis
how is parenchyma divided?
septa divide parenchyma into lobules
what's unique feature of submandibular gland? understand pic
serous demilunes (half moon) - these are artifacts of fixation
sebaceous glands are what type?
simple acinar glands
sweat glands are what type?
simple coiled tubular glands (merocrine secretion)
intercalated ducts + intralobular ducts are lined by what?
simple epithelium
interlobular ducts are lined by what (mostly)?
stratified epithelium
when you have serous secretion, ducts will mostly be...
striated
where are myoepithelial cells present?
sweat, salivary, and mammary glands
what's on apical surface?
tight junctions
what's an important consideration for ion and fluid transport across epithelium?
tight junctions! seal off apical surface from basal surface
describe nucleus of myoepithelial cells
triangular or elongated nucleus
striated intralobular ducts in salivary glands secrete what?
up to 1.5 L saliva per day
how is it possible for mucus to expand after being exocytosed from mucous cells?
when mucus is released into lumen, calcium or hydrogen ions dissociate - this allows for hydration of mucus - leads to great expansion in size
