Glands

Question 1

Define gland

Answer 1

an epithelial cell or collection of cells specialised for secretion`

Question 2

How can glands be classified?

Answer 2

Destination of secretion
Structure of the gland
Nature of the secretion
Method of discharge.

Question 3

Define exocrine

Answer 3

A gland with ducts

Question 4

Define endocrine

Answer 4

A ‘ductless gland’ that secretes directly into the blood

Question 5

How can you classify glands by structure?

Answer 5

unicellular/multicellular

coiled/branched

Question 6

Define mucous glands

Answer 6

Secretions contain mucus, rich in mucins (highly glycosylated polypeptides). Such cells stain poorly in H&E sections.

Question 7

Define serous glands

Answer 7

Secretions (often enzymes) are watery and free of mucus. Eosinophilic (pink) in H&E sections.

Question 8

What are the modes of secretion?

Answer 8

• Merocrine
• Apocrine
• Holocrine

Question 9

How does Merocine secretion work? (exocytosis)

Answer 9

• 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

Question 10

How does Apocrine secretion work?

Answer 10

• 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

Question 11

How does Holocrine secretion work?

Answer 11

• Disintegration of the entire cell
• Release of contents
• Discharge of the whole cell

Question 12

Define endocytosis

Answer 12

Endocytosis is the process of engulfing material initially outside the cell. It is the opposite of exocytosis (merocrine secretion). Endo/Exocytosis are coupled in transepithelial transport.

Question 13

Define transepithelial transport

Answer 13

• 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.

Question 14

What is the structure of the golgi apparatus?

Answer 14

• 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

Question 15

What is the function of the golgi apparatus?

Answer 15

• Sorting into different compartments
• Packaging through condensation of contents
• Adding sugars to proteins and lipids (Glycosylation)
• Transport

Question 16

What are the possible destinations of products of the golgi apparatus

Answer 16

• Majority extruded in secretory vesicles
• Some retained for use in the cells (eg lysosomes)
• Some enter the plasma membrane (Glycocalyx)

Question 17

What mechanisms can control secretion?

Answer 17

Nervous
Endocrine
Neuro-endocrine
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