Netters Epithelium

Question 1

Describe the simple squamous, the function, and location

Answer 1

Single layer of fat cells with spindle shaped nucleus.
Lines, exchange, and lubricates
Lining of blood vessels (endothelium), body cavity (mesothelium), organs (serosa), and respiratory spaces (alveoli)

Question 2

Describe simple cuboidal, function, and location.

Answer 2

It is a single layer of cells with equal half and width with a round centrally placed nucleus.
Absorption, secretion
Small ducts of exocrine glands, surface of the ovary, kidney tubules, thyroid gland follicles

Question 3

Simple columnar, location, function

Answer 3

Simple ColumnarSingle layer of cells taller than they are widewith a round or oblong nucleus located centrally or towardthe basal region of the cell.
Function –absorption and secretion; protection; lubrication
Location –lining of gastrointestinal system; lining of some large ducts, and lining of gall bladder

Question 4

Stratified Squamous

Answer 4

multiple layers of cells with the outermost layer of cells squamous-shaped.
Function –protection; secretion
Location –epidermis, lining of oral cavity, esophagus, and vagina

Question 5

Stratified cuboidal, function, location

Answer 5

Multiple layers of cellswith the outermost layer cuboidal-shaped.
Function –absorption and secretion
Location –sweat glands and ducts, larger ducts of exocrine glands

Question 6

Stratified columnar

Answer 6

Multiple layers of cellswith the outermost layer columnar-shaped
Function –secretion, absorption, protection
Location-largest ducts of exocrine glands and conjunctiva of e

Question 7

Pseudostratified

Answer 7

although it appears stratified, is composed of only one cell layer of generally columnar cells. ALL cells touch the basement membrane even though they do not all reach the luminal surface. Typically have cilia on apical surface
Function –secretion, absorption, lubrication Location –Lining of trachea, bronchi, nasal cavity, reproductive tract (ductus deferens and oviduct)

Question 8

Transitional (urothelium)

Answer 8

Stratified epithelium found exclusively in parts of the renal system. The shape of the top layer can change based on distension of the underlying tissue. Accurate classification depends on knowing where it is found.
Function –distensibility
Location –urethra, bladder, ureters, renal calyces

Question 9

What is mucus

Answer 9

Glycoproteins and water

Question 10

What is serous

Answer 10

Proteins and water

Question 11

What is the merocrine/eccrine mechanism of secretion?

Answer 11

Product is released by exocytosis from membrane bound granules or vesicles that fuse with the apical cell membrane.

(They leave without the apical cell membrane)

Question 12

What is the apocrine mechanism of secretion?

Answer 12

Product released with a small portion of apical cytoplasm and membrane. (E.g. mammary gland secretion of milk lipids)

Question 13

What is the holocrine mechanism of secretion?

Answer 13

The secretory product constitutes the entire cell and it’s products (e.g. sebaceous gland

Question 14

What are the symmetrical cell junctions?

Answer 14

Tight junctions, desmosomes, and gap junctions?

Question 15

What are the asymmetrical cell junctions?

Answer 15

Hemidesmosomes

Question 16

What do tight junctions connect? What is their function?

Answer 16

The create a boundary between the apical domain and the basolateral domains of an epithelial cell.
They control the passage of substances between adjacent cells, they are created by localized sealing of adjacent plasma membranes bear the apical regions of adjacent cells.
They consist of several proteins that interact with cytoplasmic F actin (occludin, Claudin, and ZO proteins)

Question 17

What is the function of a desmosome, how do they connect cells?

Answer 17

They provide mechanical anchoring and maintain the integrity of the epithelial surface by resisting cell-cell separation.

They consist of a plaque that contains proteins desmoplakin, plakoglobin, and plakophilin that interact with cytoplasmic keratin filaments on one side and adhesion molecules (desmocollin and desmoglein) on the other

Question 18

What do gap junctions do?

Answer 18

They mediate intercellular communication by permitting the passage of small molecules between adjacent cells.
Formed by integral membrane proteins called connexins that form a connexon. The end to end alignment of connexons in adjacent cells provide a direct channel of communication between cytoplasm of two adjacent cells.
Allow for coordinated response and activity in epithelium
Several diseases occur when connexins are mutated

Question 19

What are hemidesmosomes? What are their function?

Answer 19

Asymmetrical cell junction located in basal cell membrane that anchor cells to basal lamina.
Consists of cytoplasmic plate associated with cytoplasmic keratin filaments, and outer membrane plaque that links cell to basal membrane by anchoring filaments and integrin proteins.
Disruption of hemidesmosomes in epithelium of skin causes blistering (bully’s pemphigoid)

Question 20

What are cilia? What is their function?

Answer 20

They are motile cell projection consisting of microtubules (9+2)
They function for defense and transport of material outside the cell

Question 21

What are microvili and function?

Answer 21

They are finger like projections of apical cell surface. They have a core of actin-containing microfilaments.
Their primary function is for absorption. They are non motile and increase absorptive surface area.

Question 22

Describe two components of basement membrane.

Answer 22

Basal lamina-sheer luke connective tissue in contact with basal surface of epithelial fell. Consists of protein laminin and type IV collagen and is produced by the epithelial cells themselves.
The reticular lamina is type III collagen and it supports the basal lamina. It is continuous with surrounding connective tissue.

Question 23

How do epithelial cells bind to basal lamina?

Answer 23

Via receptors on cell surface called integrins.
Integrins are transmembrane heterodimers formed by alpha and beta subunits that bind specific sequence (RGD) amino acids in the laminin molecule.
The interaction is important in regulating epithelial cell behavior and cell proliferation.