Glands Intro Flashcards
Define Gland.
An epithelial cell or aggregate of epithelial cells, that are specialised for the secretion of a substance.
Define secretion.
The production and release of materials by a cell or aggregate of cells.
What is the main function of glands?
To regulate human physiology, they receive signals from brain, circulating chemicals and surrounding cells. Release products to maintain balance and causes events
Describe an endocrine gland.
No duct
Secrete hormones directly into blood to work at distance
Eg pituitary or thyroid
ALL the epithelial cells in the gland secrete the hormone
Describe an exocrine gland.
Have a duct
Secrete enzyme/lubricant to specific location
Eg salivary, pancreas,mammary, sweat, sebaceous and lachrymal
ONLY cells at apex of duct secrete product
Describe usual endocrine histology.
Follicle in middle (stores Hormone)
Follicular cells (simple cuboidal) around edge
Near a blood vessel
Describe usual exocrine histology
Possess lumen
Complex secretory cells-more layers
Basement membrane is present
How do exocrine glands develop in utero?
1) fibregras growth signal received so epithelium frowns down toward msyenchymal cells.
2) EC Protien degradation enzymes break any cells in the way
3) centre cells die to produce a duct (cannicularisation)
How do endocrine glands develop in utero?
1) Fibregras growth signal makes epithelium grow toward mysenchymal cells
2) EC protein degradation enzymes break cells in way
3) produce angiogenic factors to stimulate blood vessel growth in and around epithelial cells
4) link to mother cells broken by apoptosis
How does the development of thyroid glands in utero differ from other endocrine glands?
Colloid is produced between cells to cause the follicle to become spherical
How does branching occur?
FGF10 ( a foetal growth factor) released by immature fibroblasts, epithelial cells move towards this.
Tubule elongation=(GF1 active + GF2 inactive)
Tubule branching=(GF1 inactive + GF2 active)
What shapes can a duct form?
Simple , branched, or compound
Aveolar/acinus produce surfactants
What are the cells at the secretory end of an exocrine duct called?
And what are their features?
Myoepithelial cells.
Features of both smooth muscle and epithelial cells. They help eject from secretion duct by squeezing like muscle
What are the 2 secretion Product types?
Mucous and serous
What what are the 4 types of secretion processes? Describe them
Merocrine-fusion of vesicles with apical membrane, exocytosis
Apocrine-partial loss of cytoplasm (a-piece)
Holocrine-complete loss of cytoplasm/cell
Cytochrine-cells released as secretion
