Epithelium

Question 1

What are the functions of epithelium?

Answer 1

1) PROTECTION of the underlying tissue from trauma
2) SECRETION: mucus, enzymes, hormones
3) ABSORPTION ( via endocytosis/pinocytosis) substances from lumen, eg intestine & kidney
4) TRANSPORT OF MATERIAL ON THE EPITHELIAL SURFACE (cilia) and TRANSCELLULAR TRANSPORT across epithelium (diffusion & vesicle mediated)
5) SELECTIVE PERMEABILITY of intercellular junction
6) SENSORY CELLS: taste bud, retina & hair cells in ear

Question 2

Define simple epithelia

Answer 2

All cells contact the basement membrane and all cells reach the free surface

Question 3

Define pseudostratified epithelia

Answer 3

All cells touch basement membrane but not all reach the free surface

Question 4

Define stratified epithelia

Answer 4

Only basal layer of cells touch basement membrane, not all cells reach free surface

Question 5

Define transitional epithelia

Answer 5

Type of stratified epithelia where the surface cells change between squamous and cuboidal shapes

Question 6

Function of simple squamous epithelium

Answer 6

Involved in passive transport (diffusion) of gasses or fluids

Question 7

Types of simple squamous epithelium

Answer 7

Endothelium
Mesothelium

Question 8

Functions of simple cuboidal epithelium

Answer 8

Excrete, secrete, or absorb

Question 9

Where can simple cuboidal epithelium be found?

Answer 9

Lining the small ducts and tubules, e.g. ducts of salivary glands and pancreas; collecting tubules of kidney

Question 10

Where are simple columnar epithelium found?

Answer 10

Absorptive surfaces such as in the small intestine (with microvilli)

Question 11

“Strongest protection against abrasion (not to dryness)” describes what kind of epithelium?

Answer 11

Non-keratinized stratified squamous

Question 12

Where is non-keratinized stratified squamous found?

Answer 12

Oral cavity, pharynx, esophagus, anal canal, vagina, cervix

Question 13

Mucus producing glands are associated with what kind of epithelium?

Answer 13

Non- keratinized stratified squamous

Question 14

The only keratinized type of stratified squamous epithelium is the _______

Answer 14

Epidermis

Question 15

Function of keratinized stratified squamous

Answer 15

Protects against abrasion

Question 16

Where is stratified cuboidal epithelium found?

Answer 16

Lining the ducts of sweat glands in skin

Question 17

What is the function of stratified columnar epithelium?

Answer 17

Just to provide lining of ducts

Question 18

Where is stratified columnar epithelium found?

Answer 18

Lining of larger excretory ducts of exocrine glands, such as the salivary glands

Question 19

Where is pseudostratified (columnar) epithelium found?

Answer 19

Respiratory tract

Question 20

Where is pseudostratified (columnar) epithelium with stereocilia found?

Answer 20

Epididymal duct or the inner ear

Question 21

“Basal layer cells are cuboidal, intermediate cells are polygonal; and superficial are large, rounded, may contain two nuclei” describe what epithelium?

Answer 21

Transitional epithelium

Question 22

What are the top layer of cells in transitional epithelium called?

Answer 22

Dome cells or umbrella cells

Question 23

Where is transitional epithelium found?

Answer 23

Urinary system
Bladder
1/3 urethra

Question 24

“Finger-like projections extended toward the lumen”

Answer 24

Microvilli

Question 25

Function of microvilli

Answer 25

To increase surface area for the purpose of better and faster absorption

Question 26

Where is microvilli found?

Answer 26

Epithelium of small intestine and proximal convoluted tubules in kidney

Question 27

The core structure of microvilli is made up of

Answer 27

Actin

Question 28

The collection of microvilli on cells is called what?

Answer 28

Brush border

Question 29

Kinocilia (true cilia) is found where?

Answer 29

Respiratory and female reproductive tracts

Question 30

Function of cilia

Answer 30

Beat with a wave like synchronous rhythm propelling mucus in trachea or the ovum in fallopian tube

Question 31

What motor protein allows cilia to bend or move?

Answer 31

Dynein

Question 32

“Extremely long microvilli, readily visible with light microscopy. Actin core”

Answer 32

Stereocilia (non-motile cilia)

Question 33

A junctional complex encircles each cell in…

Answer 33

Simple cuboidal and simple columnar

Question 34

Zo Za Ma

Answer 34

Zonula occludens (tight junction) Zonula adherens (adhering belt) Macula adherens (desmosomes)

Question 35

What forms a collar around each cell beneath the apical surface?

Answer 35

ZO

Question 36

2 molecules of transmembrane protein ____, one from each membrane stitch the membrane together tightly (in ZO)

Answer 36

Claudin

Question 37

What are connected to ZO on the inside?

Answer 37

Actin

Question 38

Function of ZA and MA

Answer 38

Provide anchorage spots for the cytoskeleton (actin or intermediate filaments)

Question 39

What provide junctions on the basal surface of cells?

Answer 39

Hemidesmosomes & basal lamina

Question 40

Gap junctions aka _____

Answer 40

Communicating junctions

Question 41

Gap junctions contain numerous transmembrane channels called…

Answer 41

Connexons

Question 42

Each connexon is made up of…

Answer 42

6 connexins

Question 43

Functions of gap junctions

Answer 43

1) control growth, development, cell recognition, and differentiation 2) GJ more numerous in embryonic epithelia —> exchange of signaling molecules 3) also for electrical coupling of visceral and cardiac muscle cells —> permitting synchronous contraction

Question 44

Function of hemidesmosomes

Answer 44

Mediate adhesion of epithelium to basement membrane

Question 45

What is the basal lamina made up of?

Answer 45

Type 4 collagen, laminin, entactin, & proteoglycans

Question 46

Below the basal lamina is the _____ which is made up of ____

Answer 46

Reticular lamina Type 3 collagen

Question 47

Glandular epithelium: With ducts ______ W/O ducts _____

Answer 47

Exocrine gland Endocrine gland

Question 48

Characteristics of goblet cells

Answer 48

Unicellular Synthesis & secretion of mucus Basal cytoplasm: organelles for synthesis

Question 49

Where are goblet cells found?

Answer 49

Respiratory & gastro-intestinal tracts