Histology - Epithelia

Question 1

What are the 4 basic tissue types

Answer 1

Epithelia; connective; muscle; nervous

Question 2

What is the purpose of surface epithelia

Answer 2

Covers or lines surfaces, cavities and tubes

Question 3

What are epithelia cells composed of

Answer 3

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

Question 4

What is the adhesion between cells like

Answer 4

It is strong; thus cellular sheets are formed

Question 5

What layer of the skin is made up of epithelial cells

Answer 5

The epidermis

Question 6

What are 3 common features of epithelial cells

Answer 6

Usually polarised; bind together in sheets; non-vascular

Question 7

Name 3 functions of epithelia

Answer 7

Mechanical barrier (skin); absorption (lining of intestine); locomotion (cilia in oviduct)

Question 8

Name the 2 types of cellular components that are vital to the function of epithelia

Answer 8

The cytoskeleton; intercellular junctions

Question 9

Name the 3 classes of filaments that form the cytoskeleton in cells (smallest to biggest)

Answer 9

Microfilaments (5 nm); intermediate filaments (~10 nm); microtubules (25 nm)

Question 10

What are microfilaments composed of

Answer 10

Fine strands of the protein actin

Question 11

What are microfilaments’ main functions

Answer 11

Anchorage, movement and extension of the cell membrane

Question 12

What are intermediate filaments’ main functions

Answer 12

Bind intercellular elements together and to the cell membrane

Question 13

What are microtubules composed of

Answer 13

2 types of tubulin subunits; alpha and beta

Question 14

What are microtubules important for

Answer 14

Movement of components in the cell and during cell division

Question 15

What are intercellular junctions

Answer 15

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

Question 16

Name the 3 types of junctions found in epithelial cells

Answer 16

Occluding; anchoring; communicating

Question 17

What are occluding junctions’ main functions

Answer 17

Inhibit diffusion; the focal region of close apposition between adjacent cell membranes

Question 18

Name the 2 forms of anchoring junctions

Answer 18

Zonunla adherens; desmosomes

Question 19

Describe how zonula adherens hold cells together

Answer 19

Link tightly onto opposite cells

Question 20

How do desmosomes hold cells together

Answer 20

Link submembrane intermediate filaments of adjacent cells together

Question 21

What do communicating junctions (gap junctions) allow between cells

Answer 21

Selective diffusion of small molecules and ions

Question 22

Describe the structure of each junction

Answer 22

Circular patch studded with several hundred pores

Question 23

What is an area with close association of several junction types called

Answer 23

A junctional complex

Question 24

What are the 3 epithelial cell shapes

Answer 24

Squamous; cuboidal; columnar

Question 25

What is one layer of epithelial cells called

Answer 25

Simple layer

Question 26

What are several layers of epithelial cells called

Answer 26

Stratified

Question 27

Describe what pseudostratified is

Answer 27

Appears stratified but all cells contact basal lamina

Question 28

What are microvilli’s main function and roughly how big are they

Answer 28

Increase the surface area of the cell membrane; 0.5-1 micro metres

Question 29

What are cilia’s main function and roughly how big are they

Answer 29

Propel mucous or fluid over the cell surface; up to 10 micro metres

Question 30

What are keratins

Answer 30

Group of tough structural proteins; dead material that accumulates