Glandular Tissue And Secretion Flashcards
Define exocrine gland
With duct
Define gland
An epithelial cell specialised for secretion
Define endocrine gland
Ductless, secrete directly into blood
Define merocrine secretion
By exocytosis
1) membrane bound compartment migrates to surface
2) fuses with membrane
3) contents released into extra cellular space
Define apocrine secretion
Non,embrace bound e.g. Lipid approaches surface
Makes contact and pushes up apical membrane
Thin layer of apical cytoplasm drapes around droplet
Membrane surrounding droplet pinches off from cell
Plasma membrane transiently smaller
Describe holocrine secretion
Disintegration of the cell
Release contents
Discharge of whole cell
Describe the mechanism of endocytosis
1) engulf material from outside cell
2) pinch off part of membrane to form a vesicle
3) membrane bound within the cell
How to endo and expcytosis allow trans epithelial transport?
Material endocytosed at one surface
Transport vesicles shuttles across cytoplasm via microtubules
Material exocytosed st opposite surface
Describe the structure of the golgi
Stack of disc shaped cisternae
One end of discs flattened, the other concave
Discs have swellings at edges
Describe function of the golgi
Transport tbrough sequential golgi cisternae
Packaging kf sorted contents through condensation
Glycosolation of proteins and lipids
Where is the destination of products from the golgi?
In secretory vesicles some retained in cell for jse e.g. Lysosome others enter plasma membrane (glycolyx)
Why is the golgi important?
Branching sugars offer complex shapes for specefic interactions
Destruction of this layer bu enzymes alters many specificity based properties of cells e.g. Adhesion, mobility, communication
Describe role of secretion in cell functions
?
Describe nervous control of secretion
Sympathetic nervous stimulation of adrenal medullary cells leads to release of adrenaline
Describe endocrine control of secretion
Adrenocorticotrophic hormone stimulates coretex of adrenal gland to release cortisol
Describe neuro-endocrine control of secretion
Nervous cells of hypothalamus control acth secretion from anterior pituatory
Describe negative feedback secretion control
Inhibitory effect of high t3/t4 levels on tsh synthesis in anterior pituatary
How are the majority of glands derivatives of epithelial tissues?
Were surface epithelia that have specialised to particular function, epithelial cells proliferate and leave surface to invade underlying connective tissue where basal lamina surrounds newly formed gland
What is the difference between endo and exocrine glands?
Exo into duct, endo into vascular (blood) or lymphatic system
What is the difference between simple and compund glands?
Simple dont branch, compound do
Describe the shape of acinar and tubular glands
Acinar - alveolar bubbles
Tubular - tube like
Describe the difference between serous and mucousal glands
Serous - watery secretionx free of mucus (enzymes)
Mucous - mucous rich mucins (dont stain well)
Describe goblet cells in jejunum
Goblet cells interspersed with simple columnar
Synthesise mucus and secrete it onto elithelial surface where it lubricates and acts as a protective barrier
Narrow stalk attaches swollen, mucous rich upper part if each goblet cell to basement membrane
Desfibe goblet cells large intestine
Crypts of liberkhun - simple tubular lined by water absorbative collumnar cells and mucus secreting goblet cells
As water is absorbed from gut mucus allows adherence of solid waste into a compact mass and also protects the epithelium from trauma
