L5- Glands introduction Flashcards
definition of a gland
‘An epithelial cell or an aggregate of epithelial cells that are specialised for the secretion of a substance’
secretion
production and release of materials by a cell or aggregate of cells
types of gland
endocrine and exocrine
glands are typically classified according to
their structure and how the products are released
endocrine
ductless
- secrete directly into the blood flowing through them
exocrine
ducted
- secrete into a location or region of the body through a duct
what do endocrine glands secrete
hormones
- that work at distant parts of the body
what do exocrine glands secrete
enzyme and lubricants
name three endocrine glands
1) Pituitary gland
2) Thyroid gland
3) Parathyroid gland
where is the pituitary gland found
the hypothalamus (beneath the thalamus)
what does the anterior pituitary gland produce
hormones that regulate most of the glands of the endocrine system
e.g. ACTH LH FSH TSH Prolactin Somatorophin
prolactin
stimulates milk production in mothers
somatorophin
regulates growth of the body and tissue
what does the posterior pituitary gland produce
- vasopressin (ADH)
- Oxytocin
vasopressin (ADH)
prevents water loss from the kidney
Oxytocin
that signals for delivery in pregnant women at the end of gestation and ejection of milk during breast feeding
thyroid gland produces
thyroid hormone- T3 and T4
T3 and T4
control metabolism, calcitonin (calcium homeostasis)
parathyroid produces
produced parathyroid hormones, calcium homeostasis
example of exocrine cells
- salivary gland
- pancreas gland
- mammary gland
- sweat glands
- sebaceous gland
- lachrymal gland
generation of gland- in utero development
- Growth signal received (FGF family member)
- Proliferation of [daughter] cells occurs and extracellular protein degradation of enzymes produced
- Epithelial cells invade space created
a. Exocrine glands
i. Central part dies off to produce duct (canalicularisation)
b. Endocrine glands
i. Produce angiogenic factors to stimulate blood vessel growth in and around the epithelial cells
ii. Link to [mother] cells broken through apoptosis
in thyroid follicles (endocrine) production of colloid between epithelial cells causes
expansion of follicle into a sphere
endocrine glands are surrounded by
capillaries- quick transport fo hormones into the blood and to distant tissues
hormone release in endocrine cells
directly released from cells e.g. B cells- insulin
release of enzymes and lubricants from exocrine cells
secretory cells form an acids (circle shape)- all cells secrete into the acinus and the product from many cells gets released from a single duct
two types of cells in exocrine glands
epithelial
- cells lining the duct
- cells that make secretly products
some cells at the end of the ducts change morphology and class by turning into
myoepithelial cells
myoepithelial cells
have features of both epithelial and smooth muscle cells
- help eject sections from the duct
types of duct structure
tubular
alveolar
compound
simple
simple
duct does not branch e.g. intestinal glands