Epithelial Glands Flashcards
How do exocrine glands secrete things?
Via a duct derived from the original connection to the epithelial layer.
What part of the epithelium degenerates in endocrine glands?
epithelial down growth; this causes the secretory tissue to be separated from its epithelial leyer.
How do endocrine glands secrete things?
via diffusion into surrounding blood vessels.
What are exocrine grands?
> epithelial outgrowths into underlying connective tissue that retain their connection to the overlying epithelium in the form of one or more ducts.
> secretory products are transported via a duct system (usually) to the lumen or surface of an organ
What are endocrine glands?
> glands that are epithelial outgrowths into underlying connective tissue that lose their connection to the overlying epithelium.
> They lack ducts and must secrete their product (hormone) directly into surrounding blood vessels
What are paracrine glands?
glands in which secretion affects neighboring cells; e.g. growth factors.
What are autocrine glands?
> glands whose secretions affect the cell that released the secretory product.
E.g. IL-2 secreted by T cells.
What are acinus cells?
a mostly mucous capped by a half-moon shaped group of serous cells forming a serous demilune.
What is merocrine secrection?
secretion in which the secretory product is in vesicles and is released by endocytosis/exocytosis.
What is apocrine secretion?
secretion in which the apical cytoplasm is released along with the secretory product.
What is holocrine secretion?
secretion in which the entire cell is released as part of secretory product.
What is the submandibular gland composed of?
serous and mucuous cells, with demilune around the serous cells. Myoepithelial cells surround acini.
What is the sublingual gland composed of?
mucuous acini and flattened nuclei at basal poles of cells.
What is the parotid gland composed of?
serous acini and zymogen granules. RER predominates in the basal regions of secretory cells.
What is a compound gland divided into?
subunits (lobules)
What is a lobule equivalent to?
A simple branched gland.
What is the parenchyma?
The components of the gland derived from epithelium (secretory units and ducts) comprise the parenchyma.
What is stroma?
The connective tissue capcsule surrounding the entire gland as well as the connective tissue partitions separating the lobules and lobes.
What are acini?
The secretory components of a lobule. They may be serous, mucuous or sero-mucous. They are covered by the basement membrane and border myoepithelial cells.
What are myoepithelial cells?
cells that have extensive actin bundles and also contract. They express secretions of the acini into intercalated ducts.
What are intralobular ducts?
> ducts that lie within a lobule.
> they can be intercalated or striated.
What are intralobar ducts?
ducts joined by two or more interlobular ducts. They are lined with columnar epithelium transitioning into stratified column epithelium.
What are the major salivary glands?
parotid gland, submandibular gland and sublingual glands
Glandular tissue is composed of what type of cells that are specialized for secretion
> epithelial cells
Epithelial down growth may remain connect to the epithelial layer from which it originated. This rise to which type of gland?
> exocrine gland
List some examples of exocrine glands.
> salivary glands > mammary glands > sweat glands > sebaceous glands > liver > pancreas
List some examples of endocrine glands.
> pituitary > thyroid > pineal > parathyroids > adrenals > gonads > liver > pancreas
Ducts can be classified based on what?
> number of cells comprising the gland
absence or presence of ductal branching
shape of secretory portion
Simple multicellular glands do not exhibit what?
> they do not exhibit ductal branching
Ductal branching is characteristic of which types of glands?
> compound multicellular glands
What are the possible shapes of the secretory portions of gland that are used to classify them?
> tubular
alveolar (acinar)
tubuloalveolar (-acinar)
List the different types of tubular glands and a location for each.
> straight
» crypts of Lieberkuhn in large intestine
> coiled
» sweat glands of skin
> branched
» fundic , pyloric, and cardiac glands of the stomach
The term acinar is synonymous with what other term for glandular shape?
> alveolar
List some possible examples of alveolar (acinar) glands
> meibomian glands of eyelids
> sebaceous glands of skin
List some examples of tubuloalveolar (-acinar) glands
> salivary gland
Brunner’s gland of duodenum
mucous glands of esophagus
What are the simple glands?
> simple tubular
simple tubular coiled
simple tubular branched
simple alveolar (acinar)
What are the branched glands?
> branched tubular
branched alveolar (acinar)
branched tubuloalveolar (-acinar)
Characterize a serous secretion
> watery, enzyme-filled secretion
> example: parotid gland
Characterize a mucous secretion
> thick, mucin containing secretion
Characterize a mixed (serous-mucous) secretion
> secretion is a combination of serous and mucous
acinous is typically mostly mucous capped by a half-moos shaped group of serous cells forming a serous demilune
example: submandibular and sublingual glands
Glands can also be characterized by mechanism of secretion. What are these?
> merrocrine (eccrine)
apocrine
holocrine
Merocrine (eccrine)[mechanism of secretion]
> secretory product is typically stored in membrane-bound vesicles, and cytoplasm/cell membrane is retrieved in an exocytosis/endocytosis cycle
> includes most glands
Apocrine (mechanism of secretion)
> apical cytoplasm is released along with secretory product
> example: axillary sweat glands
Holcrine ( mechanism of action)
> entire cell is released as part of secretory product
> example: sebaceous gland
Characteristics of the submandibular gland?
> both serous and mucous cells
serous cells form serous dumilune capping mucous acini
myoepithelial cells surround acini
Characteristics of the sublingual gland?
> mucous acini (pale in appearance) (PAS+)
flattened nuclei at basal poles of cells
myoepithelial cells surround acini
Characteristics of the parotid gland?
> serous acini
apical regions contain zymogen granules
RER predominates in basal regions of secretory cells
