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