Session 2.2 Glands Flashcards
Definition of a gland
An epithelial cell or collection of cells specialised for secretion
Give the four ways in which glands can be defined
Destination of secretion, structure of the gland, nature of the secretion and method of discharge
Whena are multicellular glands classed as simple?
When their ducts don’t branch
Name the two types of structure glands can be?
Alveolar (acinar) or tubular
What type of gland is this? Where is it found?
Simple Tubular
Intestinal glands
What type of gland is this? Where is it found?
Simple Coiled tubular
Merocrine Sweat Glands
What type of gland is this?
Where is it found?
Simple branched tubular
Gastric Glands
What gland type is this? Where is it found?
Simple branched alveolar
Sebacous glands
What type of gland is this? Where is it found?
Compound alveolar
Mammary glands
What kind of gland is this? Where is it found?
Compound tubular, mucous glands
What kind of gland is this, and where is it found?
Compound tubuloalveolar
Salivary glands, pancreas
What are the two types of classification by destination?
Exocrine and endocrine
Define exocrine
A gland with ducts
Define endocrine
A ductless gland that secretes directly into blood
What are the two types of secretory gland?
Mucous and Serous
What do mucous glands produce? How well do they stain?
Secretions contain mucous, rich in mucins (highly glycosylated polypeptides). Stain poorly in H&E.
What do serous glands secrete? How well do they stain, and what colour?
Watery, mucus free secretions which often contain enzymes. Eosinophillic (pink) in H&E stains.
Give three methods of secretion
Merocrine, Apocrine, Holocrine
Name two merocrine glands, and give the process of secretion (5)
Salivary glands, pancreas
Membrane bound vesicle approaches cell surface
Vesicle fuses with plasma membrane
Contents of vesicle are in continuity with the extracellular space
Plasma membrane is very slightly larger
Membrane retrieved, stabilising cell surface area
Name an apocrine gland and give its step by step method of secretion (6)
mammary gland (myoepithelial cells assist secretion)
Non-membrane bound structure (e.g. a lipid) approaches cell 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 is very slightly smaller
Membrane added to regain original surface area
Give a holocrine gland, and outline its method of secretion (3)
What is endocytosis, and in what process is it useful?
Endocytosis is the process of engulfing material initially outside the cell.
Endo/Exocytosis are coupled in transepithelial transport.
What is merocrine secretion also known as?
Exocytosis
Why is transepithelial transport good?
Because it allows molecule too large to penetrate membranes to be shunted across from one component of the body to another.
Give process of transepithelial transport (3)
Material is endocytosed at one surface of the cell
The transport vesicle shuttles it across the cytoplasm
The material/vesicle is then exocytosed at the opposite surface.
Give four features of the structure of the golgi apparatus
Stack of disc-shaped cisternae
One side of the discs are flattened, other side is concave
Discs have swelling at their edges (Vesicles that bud off)
Distal swellings pinch off as migratory Golgi Vacuoles
Give four functions of golgi apparatus
Give three product destinations of golgi apparatus
What does glycosylation do to a cell?
Branching sugars offer complex shapes for specific interactions in the glycocalyx
Allows
Adhesion to substrates & neighbouring cells
Communication with neighbouring cells
Contact inhibition of movement and division
Mobility of cells
What does enzymatic destruction of glycocalyx alter?
Adhesion to substrates & neighbouring cells
Communication with neighbouring cells
Contact inhibition of movement and division
Mobility of cells
Give four mechanisms of secretory control
Nervous Control
Endocrine control
Neuro-endocrine control
Negative feedback chemical mechanism
Give example of nervous control
Give example of endocrine control
adrenocorticotrophic hormone (ACTH) stimulates the cortex of the adrenal gland to secrete hormones (e.g. Cortisol)
Give example of Neuro-endocrine control
nervous cells of the hypothalamus control ACTH secretion from the anterior pituitary gland
Give example of Negative feedback chemical mechanism
the inhibitory effect of high thyroxine (T3 & T4) levels on TSH synthesis by the anterior pituitary gland.
Give three example of exocrine glands
Give four examples of endocrine glands
