histo lec - glands Flashcards
Originate from an epithelium that penetrates C.T and forms secretory units
glands
protein in aqueous solution: hormones, acids, oils.
Secretion
Consists of a functional portion (parenchyma) of secretory and ductal epithelial cells, which is separated by a basal lamina from supporting connective tissue elements (Stroma)
glands
Classification based on the site of secretion:
exocrine
endocrine
paracrine
Classification based on the site of secretion
No duct, release secretion into blood vessels
Products are called hormones
Thyroid, adrenal and pituitary glands
endocrine
Classification based on the site of secretion
Contain ducts, empty onto epithelial surface
Sweat glands, Oil glands, Salivary glands, Mammary glands
Exocrine glands
Classification based on the site of secretion
secrete into the local extracellular space
Paracrine glands
type of Exocrine glands
unicellular
multicellular
glands composed of single cell (goblet cell)
unicellular
Multicellular glands secrete the following substances:
– a viscous material that usually protects or lubricates cell surfaces (e.g. goblet cells, salivary glands, surface cells of stomach).
Mucus
Multicellular glands secrete the following substances
- contain both mucous and serous components
Mixed secretions
Multicellular glands secrete the following substances:
– are watery and often rich in enzymes (e.g parotid gland and pancreas)
serous
Mechanisms of Secretion
merocrine, holocrine, apocrine
Just released by exocytosis without altering the gland at all.
Ex: Sweat glands and salivary glands
Merocrine
The gland ruptures and releases secretion and dead cells as well.
Disintegration of cells
Sebaceous (oil glands on the face) only example
Holocrine
