Anatomy 9 - Epithelia

Question 1

What is epithelia composed of

Answer 1

Closely aggregated, polyhedral epithelial cells with a minimum of intercellular substance

Question 2

Adhesion between epithelia is

Answer 2

Strong

Question 3

What is epithelia able to cover

Answer 3

Exposed external surface and internal cavities

Question 4

Common features of epithelia

Answer 4

Usually polarised, have a sheet like structure at their basal surface composed of extracellular matrix called the basal lamina, nearly all are non-vascular and they tend to bind together in sheets

Question 5

Surface epithelia

Answer 5

Cover or line surfaces, cavities and tubes

Question 6

What are epithelial tissues derived from

Answer 6

All of the embryological germ layers: ectoderm, endoderm and mesoderm

Question 7

Functions of epithelia

Answer 7

Mechanical barrier, chemical barrier, adsorption, secretion, containment, locomotion by cilia, sensation and contractility

Question 8

Example of mechanical barrier epithelium

Answer 8

Skin

Question 9

Example of chemical barrier epithelia

Answer 9

Lining of the stomach

Question 10

Example of adsorption epithelia

Answer 10

Lining of the intestine

Question 11

Example of secretion epithelia

Answer 11

Salivary gland

Question 12

Example of containment epithelia

Answer 12

Lining of urinary bladder

Question 13

Example of locomotion by cilia epithelia

Answer 13

Oviduct

Question 14

Example of sensation epithelia

Answer 14

Taste buds

Question 15

Example of contractile epithelia

Answer 15

Myoephithelial cells

Question 16

Function of cytoskeleton

Answer 16

To maintain cellular integrity

Question 17

Three main classes of filaments in the cytoskeleton

Answer 17

Microfilamnets, intermediate filaments and microtubules

Question 18

What is the function of the filamentous proteins

Answer 18

They become attached to cell membranes and to each other by anchoring and joining proteins to form a dynamic 3D internal scaffolding in the cell

Question 19

What are microfilaments composed of

Answer 19

The protein actin

Question 20

Functions of microfilaments

Answer 20

Anchorage, movement and extension of the cell membrane

Question 21

Function of intermediate filaments

Answer 21

They bind intercellular elements together and to the plasmalemma

Question 22

What are microtubules made up of

Answer 22

The two tubulin subunits, alpha and beta

Question 23

Functions of microtubules

Answer 23

Move components of the cell

Question 24

What are intercellular junctions

Answer 24

Specialised membrane structures which link individual cells together into a functional unit

Question 25

What are the three types of membrane junctions

Answer 25

Occluding junctions, anchoring junctions and communicating junctions

Question 26

What are occluding junctions

Answer 26

They link cells to form a diffusion barrier

Question 27

What are anchoring junctions

Answer 27

They provide mechanical strength

Question 28

What are communicating junctions

Answer 28

Allow movement of molecules between cells

Question 29

What is linked together in anchoring junction

Answer 29

Submembrane actin bundles

Question 30

If the outer layer of adjacent cells appear fused it is known as

Answer 30

A pentalaminar structure

Question 31

What are desmosomes

Answer 31

They lin k submembrane intermediaries filaments of adjacent cells

Question 32

What do desmosomes provide

Answer 32

Mechanical stability

Question 33

What is found in the cell membranes of communicating junction cells

Answer 33

Several hundred pores

Question 34

What are epithelia classified by

Answer 34

Cell shape, number of layers of cells, cell surface specialisation and the presence of any specialised cell type

Question 35

What are the different cell shapes

Answer 35

Squamous, cuboidal and columnar

Question 36

What are the different number of layers of cells called

Answer 36

Simple - one layer Stratified - two or more layers Pseudostratified - tissue appears to have multiple layers, but in fact all cells are in contact with the basal lamina

Question 37

What are the cell surface specialisation categories

Answer 37

Prominent microvilli, cilia and keratinised

Question 38

What specialised cells can be present in epithelia

Answer 38

Goblet cells