TOB Session 2 Flashcards
Define ‘Gland’
An epithelial cell or collection of cells specified for secretion
What are the 4 means of classification of a gland?
Destination of secretion, Method of secretion, Nature of secretion, Structure of gland (DMNS)
What is an exocrine gland?
A gland with ducts
What is an endocrine gland?
A gland without ducts that secretes directly into the bloodstream.
Into what categories can the structure of a gland be classified?
- Unicellular/Multicellular
- Coiled/Branched/Neither
- Tubular/Alveolar/Tubuloalveolar
- Simple/Compound
What is the difference between a simple multicellular gland and a compound multicellular gland?
In simple multicellular glands, the ducts do not branch. However in compound multicellular glands, the ducts do branch.
Name the eight structures into which glands can be classified.
Simple Tubular Simple Coiled Tubular Simple Branched Tubular Simple Alveolar (Acinar) Simple Branched Alveolar (Acinar) Compound Tubular Compound Alveolar Compound Tubuloalveolar
Describe the secretions of a mucous gland.
The secretions contain mucus and are rich in highly glycosylated proteins called mucins.
What colour do mucous glands stain with haemotoxylin and eosin?
They stain poorly due to the mucus.
Describe the secretions of a serous gland.
The secretions are mucus-free and watery.
What colour do serous glands stain with haemotoxylin and eosin?
They stain pink as they are eosinophilic.
Name the three kinds of secretion
Holocrine
Apocrine
Merocrine
(HAM)
Describe merocrine secretion
Membrane bound vesicle approaches cell surface and fuses with plasma membrane. The contents of the vesicle are released in to the extracellular space and the plasma membrane is now slightly larger.
Where does merocrine secretion take place (name 2 locations)?
Salivary Glands, Pancreas
Describe Apocrine secretion
Non-membrane bound structure approaches cell surface and pushes up apical membrane. Thin layer of membrane surrounds structure and pinches off from the cell. The plasma membrane is now smaller.
Where does apocrine secretion take place? (name one location)
Mammary gland
Describe holocrine secretion
In holocrine secretion, the entire cell disintegrates and releases its contents.
Give an example of a gland that secretes via holocrine secretion
Sebaceous gland
What is endocytosis?
The process of engulfing material into the cell. It is the opposite of merocrine secretion (exocytosis)
What is transepithelial transport?
When a molecule is too large to penetrate the membrane so it is shuttled across an epithelial cell. It is endocytosed at one surface, shuttled across via a transport vesicle then exocytosed at the other side.
Describe the appearance of the Golgi apparatus
It is a stack of disc shaped cisternae with one concave side. Discs have budding vesicels at their edges and distal swellings pinch off as migratory vacuoles.
What does the Golgi apparatus do?
It sorts proteins from the rough endoplasmic reticulum into different compartments and adds sugars to proteins and lipids (glycosylation).
Where do the products of glycosylation go?
The majority are released in secretory vesicles but some are retained in the cells as lysosomes and some enter the glycocalyx.
What is glycosylation and why is it important?
When sugars are added onto proteins and lipids to offer complex shapes for interaction in the glycocalyx. Sugars make the molecules more specific and alter communication with neighbouring cells, adhesion to substrates and movement/division.