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Unformatted text preview: s for the hormone.
(Paracrine signals affect target cells very near the
signal source and don’t involve the blood. Autocrine:
secreting cell is also a target cell.)
2.exocrine: involving large amounts of cell product
secreted apically into epithelial tubes called “ducts”.
cell stimulates itself! Paracrine - blood not involved - near in proximity
Autocrine - if cell secreting hormone also has receptor for it! Unicellular glands: can be endocrine or exocrine
Single endocrine cells secreting specific paracrine hormones are
fairly numerous in the epithelium lining the digestive and
respiratory systems (and will be discussed later.)
Classic unicellular exocrine glands are the mucus-secreting
some glands can be just 1 cell!
ex: certain heart muscle cells. (goblet bc of SHAPE -- specialized for MUCUS SECRETION -- abundant in pseudostrat. epithelia that line the trachea -- also simple
of GUT -- produce mucus that coats lining of gut) pseudostratiﬁed simple columnar Fig. 4-16 Fig. 4-18 How glands form during an organ’s development in the embryo: downgrowth of endothelium cells
differentiate to form HOLLOW structure
which is PARTIALLY DUCT and partially
These two portions are continuous
with lining & surr...
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- Spring '14