Lecture 3: Epithelium

Question 1

Define epithelium

Answer 1

a sheet of cells that line all body surfaces, cavities, and tubular organs

Question 2

True or False

Epithelium arise only from ectoderm

Answer 2

FALSE

epithelium arises from all three germ layers

Question 3

Main characteristics of epithelium

Answer 3

1. polar
2. avascular
3. comprised of tightly packed cells with little to no intercellular substances

Question 4

Describe the polar sheets of epithelium

Answer 4

1. it contains an apical surface on the outside

2. it has a basal surface lying on supportive CT with contains a basement membrane and basal lamina

Question 5

True or False: The basal surface of the epithelial sheet is exposed to the external environment

Answer 5

FALSE: the apical surface is exposed to the external environment

Question 6

What is the basement membrane of an epithelial cell?

Answer 6

found between the connective tissue and the cell itself. It is made up of basal lamina, laminin, and type IV collgens

Question 7

What is the role of the basal lamina?

Answer 7

it is made up of collagenous fibers and work to anchor the epithelial sheet to the underlying tissue.

Question 8

What is laminin?

Answer 8

Laminin is an adhesive molecule that is found in the basement membrane of an epithelial cell and works to anchor the epithelial sheets to its underlying tissue.

Question 9

True or False: The basement membrane is visible under light microscopy

Answer 9

TRUE –> the basal lamina is only visible under electron microscopy

Question 10

What are the two broad classifications of epithelial cells?

Answer 10

1. simple

2. Stratified

Question 11

What are the types of simple epithelium?

Answer 11

1. squamous
2. columnar
3. cuboidal

Question 12

Describe a simple squamous cell?

Answer 12

1. they are flat
2. gases and liquids diffuse across easily
3. line moist internal surfaces

Question 13

Describe the three main locations where you find simple squamous?

Answer 13

1. endothelium-line blood vessels, lymphatics and heart
2. mesothelium-line serous body cavities and outer tubular organs in the abdomen
3. epithelium(not special name)-line small tubules of the kidneys

Question 14

Describe a simple cuboidal cell.

Answer 14

width and heigh of cells are equal; line small ducts

Question 15

Where might you find simple cuboidal cells?

Answer 15

secretory ducts in the pancreas, collecting and other tubules of the kidney

Question 16

Describe a simple columnar cell.

Answer 16

Height of the cells are greater than the width; have secretory and absorptive capability

Question 17

Where might you find simple columnar cells?

Answer 17

lining most of the GI tract and in the uterus

Question 18

Describe pseudostratified columnar cells

Answer 18

stacks of columnar cells. All cells touch basal lamina, but not all cells reach the lumen; usually have cilia

Question 19

Where would you most likely find pseudo stratified epithelium?

Answer 19

where particulate matter is moved in the reproductive and respiratory tracts

Question 20

What is it meant by stratified?

Answer 20

comprised of two or more layers, the top layer defines the epithelium

Question 21

Describe stratified squamous

Answer 21

surface cells are squamous but cells below are often polyhedral; usually serves as a protective role

Question 22

What are the types of stratified squamous?

Answer 22

1. keratinized (dry, cornfield)

2. non-keratinized (wet)

Question 23

Where would you find a non-keratizined layer of stratified squamous epithelium?

Answer 23

esophagus

Question 24

What type(s) of epithelium typically line large ducts?

Answer 24

stratified columnar or cuboidal

Question 25

Define a transitional epithelium

Answer 25

layered epithelium that changes its appearance between cuboidal and columnar

Question 26

Where is transitional epithelium most likely found?

Answer 26

bladder

Question 27

What are the functions of the epithelium?

Answer 27

1. protection (skin)
2. secretion (exocrine glands)
3. absorption (intestine)
4. excretion (kidney tubules)
5. sensation (tastebuds, retina)
6. transportation (trachea)
7. reproduction (testes)

Question 28

What are the components of the apical surface of the polar epithelial cell?

Answer 28

hydrolases, glycolipids, Na ion dependent transporters, Cl ion channel