Glandular Tissue and How Cells Secrete

Question 0

Classify glandular tissue, describing the meaning of the following terms: exocrine or endocrine, merocrine, apocrine, halocrine

Answer 0

Classified by destination of secretion, structure of gland, nature of secretion, method of discharge
Destination:
Exocrine - glands with ducts, endocrine - ductless glands secrete directly into blood
Structure:
Unicellular/multicellular, acinar, tubular, coiled, branched, simple gland, compound gland
Nature:
Mucous - secretion contains mucus, stain poorly in H&E
Serous - secretions are watery and free of mucus, pink in H&E
Method:
Merocrine - exocytosis, apocrine - pinches off, holocrine - disintegration of cell

Question 1

Define a gland

Answer 1

An epithelial cell or aggregate of cells specialised for secretion

Question 2

Describe the above mechanisms of secretion

Answer 2

Merocrine - membrane bounded component leaves by exocytosis
Apocrine - non-membrane bounded structure, pinches off
Holocrine - disintegration of cell, release of contents, discharge of whole cell

Question 3

Describe the mechanisms of endocytosis

Answer 3

Engulfing material initially outside cell

Opposite of exocytosis

Question 4

Describe how endocytosis and secretion combine to give trans-epithelial transportation

Answer 4

Endo- and exocytosis are coupled in trans-epithelial transportation
Material endocytosed at one surface, transport vesicles shuffles across cytoplasm, material exocytosed at opposite surface
(For molecules too large to penetrate membranes)

Question 5

Explain the mechanism and importance of the glycosylation of newly synthesised proteins in the Golgi apparatus

Answer 5

Glycosylation = adding sugars to proteins and lipids
Glycosylation takes place in cisternae of Golgi
Specificity - adhesion to substrates and neighbouring cells, cell mobility, communication with neighbouring cells, contact inhibition of movement and division

Question 6

Describe the role of secretions in cell functions (e.g. in communication)

Answer 6

Neurotransmitters

Question 7

Describe simple mechanisms of control of secretion (e.g. nervous, endocrine)

Answer 7

Nervous (sympathetic)
Endocrine secretions (ACTH --> cortisol)
Neuro-endocrine control
Negative feedback (maintain homeostasis)