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Flashcards in 2. Epithelial tissues Deck (73)
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1

Epithelia are classified by

Shape
Layering

2

What shapes can Epithelia take?

Squamous (flattened plate-shape)
Cuboidal
Columnar

3

What are the types of layering in Epithelia?

Single layer = simple epithelium
Multi-layered = stratified epithelium

4

Where is simple squamous epithelium found?

Lung alveolar
Mesothelium (lining major body cavities)
Endothelium lining blood vessels and other blood spaces

5

Where is simple cuboidal epithelium found?

Lining kidney collecting duct
Many other ducts

6

Where is simple columnar epithelium found?

Enterocytes (intestinal absorptive)
Many other absorptive and secretory epithelia

7

Where is keratinising stratified squamous epithelium found?

Epidermis (skin)
(nuclei not visible in surface layer cells)

8

Where is non-keratinising stratified squamous epithelium found?

Linings of mouth, oesophagus, anus, cervix and vagina (nuclei are visible in surface layer cells)

9

Where is pseudostratified epithelia found?

Airway (trachea & bronchi)
Various ducts in the urinary and reproductive tracts

10

Epithelia functions require ...

Polarity
Must be directional

11

Epithelial layer surfaces

Apical surface at lumens (open) surface
Basal surface in contact with ECM

12

Basal & Lateral membrane of Epithelia are usually grouped

Basolateral membrane

13

What can segregate the epithelial plasma membrane into apical & basolateral domains?

Belt junctions

14

2 Types of cell-cell junctions between Epithelial cells

• Zonulae (continuous belts)
• Maculae (discrete spots)

15

Usually, cell-cell junctions are arranged as an apical junctional complex containing a...

Tight Junction nearest the apex and an Adherens junction just below it

16

Where are desmosomes (spot adhering junctions) often found?

Scattered throughout lateral membrane

17

What do Gap Junctions do?

Act as regions of direct communication between adjacent cells

18

What do cell-cell junctions do?

Give epithelia mechanical integrity
Act to seal intercellular pathways of the layer

19

Tight junctions seal the paracellular pathway

Prevents things passing between membrane of adjacent cell

20

Paracellular

Passing/ situated beside/between cells

21

Transcellular

Passing through cells

22

Tight Junctions allow cells to establish and maintain apical- basolateral polarity by...

Preventing the mixing of proteins and lipids between different plasma membrane compartments

23

Zonula occludens are also known as

Tight junctions

24

What is the consequence of paracellular pathways (between cells) being sealed by tight junctions?

Concentration differences across cell layers can be maintained

25

The more elaborate the network of contacts in a tight junction...

The tighter the seal

26

Which pathways do tight junctions seal?

Paracellular pathways
(Gate function)

27

What is the fence function of tight junctions?

TJ's segregate apical and basolateral membrane polarity

28

Describe the membrane in transporting epithelia e.g. distal convoluted tubules

Apical membrane contains many ion/ water channels
Basal membrane has many infoldings and mitochondria for active transport

29

What increases efficiency of absorption? How can this be achieved?

Increasing surface area
Make it longer
Fold the lining to form structures e.g. villi
Create tubular protrusions e.g. microvilli

30

Secretory tissues: The pancreas has both ... and ... functions

Exocrine
Endocrine