Epithelial Cells And Tissues - Names And Definitions

Question 1

Tissues

Answer 1

Group or groups of cells whose type, organisation and architecture are integral to its function

Made up of cells, ECM and fluid

Question 2

Extracellular matrix (ECM)

Answer 2

Material deposited by cells which forms the ‘insoluble’ part of the extracellular environment

Generally composed of fibrillar proteins embedded in a hydrated gel

May be poorly or highly organised

Question 3

Epithelial organisation

Answer 3

Epithelial cells make stable cell-cell junctions
—> continuous, cohesive layers
—> line internal and external body surfaces

Question 4

Epithelial classification

Answer 4

1. Shape
   
   • squamous
   • cuboidal
   • columnar
2. Layering
   
   • single
   • multi

Question 5

Simple squamous epithelium

Answer 5

Thin epithelium —> allows exchange to occur

E.g. lung alveolar, epithelium, mesothelioma, endothelium

Question 6

Simple cuboidal epithelium

Answer 6

Cube-shaped —> typical of the linings found in ducts

E.g. kidney collecting ducts

Question 7

Simple columnar epithelium

Answer 7

Arranged in columns —> surfaces involved in absorption and secretion of molecules

E.g. enterocytes lining the gut

Question 8

Stratified squamous epithelium

Answer 8

In the various layer the cell shape varies

Two main types:

1. Keratinizing —> filled with structural proteins —> keratin —> become hard and flattened —> protect underlying layers
2. Non-keratinizing —> do not undergo keratinisation —> retaking their nuclei and organelles

E.g. lining in the mouth, œsophages, anus, cervix and vagina

Question 9

Pseudo-stratified epithelium

Answer 9

Appears to be multi-layered —> all cells have contact with the basal lamina