Epithelia

Question 1

Four types of tissue

Answer 1

Epithelium, connective, muscle, nerve

Question 2

General features of epithelia (3)

Answer 2

Tightly packed cells, free surface, basement membrane

Question 3

How do epithelial cells get nutrition?

Answer 3

Diffusion from connective tissue

Question 4

Why are epithelial cells mitotically active?

Answer 4

To replace sloughed or damaged cells on apical surface

Question 5

How frequently do you replace dermal cells

Answer 5

15-30 days

Question 6

Functions of epithelium (5)

Answer 6

Protection, absorption, secretion, sensory reception, contractility (in glands)

Question 7

Apical processes designed to increase surface area

Answer 7

Microvilli

Question 8

Functions of microvilli

Answer 8

Usually absorption, can be secretion or sensation

Question 9

Length of microvilli

Answer 9

0.5-1 micron

Question 10

Internal structure of microvilli

Answer 10

Actin anchored to villin and terminal web

Question 11

Length of cilia

Answer 11

2-10 microns

Question 12

Function of motile cilia

Answer 12

Move materials along surface

Question 13

Locations of motile cilia (4)

Answer 13

Respiratory, middle ear, brain ventricles, uterine tubes

Question 14

Structure of motile cilia

Answer 14

9 doublet + 2 central microtubules, anchored to basal body of 9 triplets

Question 15

Cilia motility mechanism

Answer 15

Dynein move along adjacent MT’s (requires ATP)

Question 16

Function of primary cilia

Answer 16

Sensory receptor, molecule transport

Question 17

Structure of primary cilia

Answer 17

9 doublets + 0 central MT’s

Question 18

Diseases of cilia (2)

Answer 18

Polycystic kidney disease, Bardet-Biedl Syndrome

Question 19

Flagella structure

Answer 19

Ciliary (9+2) surrounded by mitochondria

Question 20

Stereocilia structure

Answer 20

Long microvilli, not motile

Question 21

Stereocilia locations (2)

Answer 21

Epididymis, inner ear

Question 22

Four types of lateral surface junctions

Answer 22

Tight (occludens), adherent, desmosome, gap

Question 23

Structure of tight junction

Answer 23

Occludin and claudin, “ziplock” of proteins in ring around cell

Question 24

Functions of tight junction (2)

Answer 24

Regulates paracellular pathway, defines domains of plasma membrane

Question 25

"Zona occludens"

Answer 25

Tight junction

Question 26

"Zona adherens"

Answer 26

Adherent junction

Question 27

Structure of adherent junction

Answer 27

Cadherens anchored to actin (terminal web) in ring around cell

Question 28

"Macula adherens"

Answer 28

Desmosome

Question 29

Structure of desmosome

Answer 29

Cadherens and binding proteins attach to intermediate filaments at single point

Question 30

Function of desmosome

Answer 30

Strongest attachment between cells

Question 31

Function of gap junctions

Answer 31

Allows passage of small molecules and ions

Question 32

Structure of gap junctions

Answer 32

Six transmembrane proteins (connexins) form connexon around central pore

Question 33

Composition of basement membrane

Answer 33

Proteoglycans, type 4 collagen, fibronectin, laminin, entactin

Question 34

Functions of basement membrane

Answer 34

Limit growth/invasion, scaffolding, diffusion of nutrients and signals

Question 35

Stain needed to see basement membrane

Answer 35

PAS

Question 36

Attachments from epithelia to basement membrane

Answer 36

Hemidesmosomes and focal adhesions (integrins)

Question 37

Diseases of basement membranes

Answer 37

Blisters! Epidermolysis bullosa, bullous pemphigoid

Question 38

Locations of simple squamous epithelium

Answer 38

Kidneys, endothelium (vessels), organ mesentary

Question 39

Locations of simple cuboidal epithelium

Answer 39

Kidney tubules

Question 40

Locations of simple columnar epithelium

Answer 40

Bronchi, intestines

Question 41

Appearance of pseudostratified columnar

Answer 41

Nuclei at different layers, multiple cell types in simple layer

Question 42

Locations of stratified epithelia (non-keratinized)

Answer 42

Esophagus, vagina

Question 43

Locations of keratinized simple squamous

Answer 43

Surface skin - any dry, abrasive surface

Question 44

Differences keratinized vs non-keratinized

Answer 44

Keratin replaces organelles, presence of nucleus, large amounts of pink-staining keratin

Question 45

Locations of stratified cuboidal epithelia

Answer 45

Sweat ducts

Question 46

Locations of stratified columnar

Answer 46

Transitional only - ie anus (strat squam to simple columnar)

Question 47

Appearance of urothelium

Answer 47

Appears stratified, dome shaped cells, stretches to thin, "squamous" layers

Question 48

Metaplasia

Answer 48

Stressed cells can change type, predisposes to carcinomas

Question 49

"Carcinoma"

Answer 49

Cancer of epithelial cells, not all cancers (sarcomas, myeloma, etc)

Question 50

Exocrine gland

Answer 50

Secretion to surface of epithelium

Question 51

Endocrine gland

Answer 51

Secretion to circulatory system

Question 52

Unicellular gland

Answer 52

Simplest type, ie goblet cell

Question 53

Goblet cells

Answer 53

Unicellular exocrine gland, release mucin to GI and respiratory for lubrication and protection, appears foamy

Question 54

Types of multicellular exocrine glands (8)

Answer 54

Simple tubular, branched tubular, coiled tubular, simple acinar, branched acinar, compound tubular, compound acinar, compound tubuloacinar

Question 55

Merocrine secretion

Answer 55

Vesicles fuse with membrane, exocytosis (most common, usually proteinaceous or watery, ex salivary, GI, sweat)

Question 56

Apocrine secretion

Answer 56

Plasma membrane buds off, contain more lipids (rare, mostly mammary)

Question 57

Holocrine secretion

Answer 57

Cell disintegrates, most oily (ie sebaceous glands)

Question 58

Serous secretions

Answer 58

Proteins, appear blue on H+E (ribosomes) while vesicles are more pink

Question 59

Mucous secretions

Answer 59

Appear foamy unless special stains