Epithelia and glands.

Question 1

What is the epithelium

Answer 1

The epithelium is a continuous sheet of one or more layers of cells connecting to each other and to the connective tissue underneath (basement membrane).
The epithelium is avascular, and depends on diffusion across basement membrane for it’s nourishment.

Question 2

What are the classifications of epithelium based on number of layers

Answer 2

Simple
Stratified

Question 3

On the basis of shape what are the types of epithelium

Answer 3

Squamous, cuboidal, columnar

Question 4

Comment on squamous epithelium

Answer 4

contains flat cells (width is much greater than the height). This facilitates transport and rapid diffusion across the epithelium.

Question 5

Comment on cuboidal epithelium

Answer 5

square/cuboidal cell shape. These cells usually active in
excretion, secretion or absorption, and the Golgi and organelles
lie between the nucleus and the apical surface.

Question 6

Comment on the columnar epithelium

Answer 6

Their widths are lesser than their heights. They are usually relevant in secretions

Question 7

Comment on simple squamous epithelium

Answer 7

Location: blood and lymphatic vessels, air sacs of lungs, lining of the heart
Function: secrets lubricating substance, allows diffusion and filtration

Question 8

Comment on simple cuboidal epithelium

Answer 8

Location: secretory ducts of small glands, kidney tubules
Function: allows secretion and absorbtion

Question 9

Comment on simple columnar epithelium

Answer 9

Location: bronchi, uterine tubes, uterus - ciliary columnar; digestive tract, bladder - nonciliated columnar epithelium
Function: allows absorbtion, secretes mucous and enzymes

Question 10

Comment on psuedostratified columnar epithelium

Answer 10

Location: trachea and most of the upper respiratory tract (ciliated cells)
Function: secretes mucus which is moved with cilia

Question 11

List the simple epithelia

Answer 11

Simple squamous
Simple cuboidal
Simple columnar
Pseudostratified

Question 12

What is pseudostratified epithelium

Answer 12

It is a simple epithelium that seems like it is stratified, because it’s nucleus are at different layers. It spans from the basement membrane to the lumen.

Question 13

What is transitional epithelium

Answer 13

This is a stratified epithelium in which the cells change
their appearance, appearing cuboidal in relaxed epithelium and
squamous when the epithelium is stretched. They are in the ureters, urethra, urinary bladder.

Question 14

Comment on stratified squamous

Answer 14

This epithelium is either keratinized (skin) or non keratinized (Mucosa)

Question 15

Comment on stratified cuboidal

Answer 15

It lines the excretory parts of the glands, e.g sweat glands

Question 16

Comment on stratified columnar

Answer 16

It lines the stomach and gallbladder

Question 17

What are the specializations of the epithelium

Answer 17

-Cilia
-Microvilli
-Keratin
-Goblet cells

Question 18

What is cilia

Answer 18

long fine projections on the apical surface that contain a
core of microtubules. Motile cilia beat rhythmically, moving
mucus on the apical surface of cells

Question 19

What is the microvilli

Answer 19

small thin protrusions on the apical surface of cells,
which contain bundles of actin fi laments, and increase the surface
area of the cell for absorption

Question 20

What are the goblet cells

Answer 20

Specialized epithelial cells that secrete mucus (glygoproteins and proteoglycans) onto the apical surface of the epithelium. These are single ‘ glandular ’ cells

Question 21

What is keratin

Answer 21

found on the outer surfaces of epithelia that experience
abrasion and water loss. Keratin is a type of intermediate filament,
which is made and secreted by epithelial cells in a highly crosslinked
form onto the outermost surface

Question 22

Draw a diagram to describe connections between the epithelium, whilst explaining the types of cell junctions

Answer 22

Check your book

Question 23

What are the classifications of exocrine glands

Answer 23

simple (unbranched duct); or
compound (branched ducts).

Question 24

Secretory regions of glands can either be…

Answer 24

tubular (alveolar, e.g., sweat glands) or
acinar (shaped like a grape, e.g., salivary glands).

Question 25

Secretions are released via…

Answer 25

• exocytosis ( merocrine secretion, i.e. sweat glands);
• rupture of the entire cell, and release of its products ( holocrine i.e. sebaceous glands);
• a mixture of the above ( apocrine , a third rare type of
secretion). E.g mammary gland

Question 26

Secretions from an exocrine gland are either…

Answer 26

• serous (watery);
• mucous (viscid, contains glycoproteins); or
• OR a mixture of the two.

Question 27

Draw a diagram to show the types of epithelial glands

Answer 27

Check the book.