Histology

Question 1

what is histology?

Answer 1

the study of tissues under a microscope, usually after the tissues have been prepared in some way

Question 2

what are the types of light microscopy?

Answer 2

confocal and fluorescence

Question 3

what is confocal microscopy?

Answer 3

can view a cell or tissue in a particular plane

Question 4

what is fluorescence microscopy?

Answer 4

involves loading a cell with a fluorescent probe

Question 5

what can the light microscopy visualizes structures as small as?

Answer 5

0.2 microns

Question 6

what can the electron microscopy visualizes structures as small as?

Answer 6

3 nm

Question 7

what is fixation?

Answer 7

chemicals cross-link proteins and inactivate enzymes that degrade cells/cellular components

Question 8

what is dehydration and clearing?

Answer 8

tissues are passed through alcohol solutions (replaces the water) and then the alcohol is removed

Question 9

what is infiltration and embedding for the tissue prep?

Answer 9

the tissue is infiltrated with a substance and then allowed to harden

Question 10

what is trimming for tissue prep?

Answer 10

tissue is sliced into thin, almost transparent slices using a microtome

Question 11

what is the process of exposing a cell to a due or molecule that improves visualization?

Answer 11

staining

Question 12

what is a hematoxlin?

Answer 12

a dark blue basic due, and will bind to negatively-charged molecules

Question 13

what is Eosin?

Answer 13

pink acidic dye and will bind to positively-charged molecules

Question 14

Periodic acid-Schiff stain or PAS is great at showing what?

Answer 14

glycogen and glycoproteins

Question 15

why is histology useful?

Answer 15

much of the function of a cell or tissue can be deduced by its microscopic structure
cells/tissues that are sick often look sick under the microscope

Question 16

is epithelium avascular or vascular?

Answer 16

avascular - no blood vessel

Question 17

what are the two ways of transport through epithelial linings?

Answer 17

paracellular and transcellular

Question 18

what does paracellular mean?

Answer 18

between epithelial cells, movements across junctions

Question 19

what does transcellular mean?

Answer 19

through epithelial cells, movement across apical and basolateral cell membranes

Question 20

name of epithelial cells/tissues if flattened?

Answer 20

squamous

Question 21

name of epithelial cells/tissues if square?

Answer 21

cuboidal

Question 22

name of epithelial cells/tissues if tall?

Answer 22

columnar

Question 23

name of epithelial cells/tissues if there’s only a single layer of epithelial cells?

Answer 23

simple

Question 24

name of epithelial cells/tissues if there’s multiple layers?

Answer 24

stratified

Question 25

stratified epithelia is named how?

Answer 25

based on the shape of the cell farthest from the base

Question 26

name of epithelial cell/tissues if there are cilia?

Answer 26

ciliated epithelium

Question 27

what are the key functions of tight junctions

Answer 27

- barrier that prevents movement of undesirable substances to the tissues below - regulates the movement of a variety of molecules between cells through the barrier - help establish polarity - tight junctions seem to help direct membrane proteins to the apical vs. basolateral sides

Question 28

what are the key proteins of tight junctions?

Answer 28

- claudins - occludin - junctional adhesion molecules -ZO proteins

Question 29

what do claudins do?

Answer 29

transmembrane proteins that can act as channels for small molecules (paracellular)

Question 30

what do occludin do?

Answer 30

transmembrane protein, function not clear

Question 31

Junctional adhesion molecules (JAM)

Answer 31

transmembrane protein that may mediate permeability to larger molecules

Question 32

what do ZO proteins do?

Answer 32

important in tight junction formation, interact with the cytoskeleton

Question 33

what are the functions of adherens junctions

Answer 33

- strengthens and stabilizes tight junctions - participates in cell-cell signaling that regulates cell division and proliferation

Question 34

what are the key proteins of adheren junctions?

Answer 34

cadherin and catenins

Question 35

what are cadherins

Answer 35

transmembrane protein that interacts with other cadherins on the neighboring cell

Question 36

what are catenins

Answer 36

linker molecules that connect the intracellular face of claudins to the actin cytoskeleton

Question 37

what are desmosomes?

Answer 37

only attach to certain spots of the epithelial cell membrane and connect to intracellular intermediate filaments ex. keratin

Question 38

what is the different between hemidesmosomes and desmosomes?

Answer 38

○ Transmembrane "linking" protein is an integrin, not a claudin-like molecule ○ Integrin binds to a component of the basement membrane known as laminin ▪ Does not bind to a molecule on an adjacent cell ○ Hemidesmosomes do not seem to have important intracellular signaling functions * Hemidesmosomes do link to intracellular intermediate filaments * Function – adhesion of the epithelial cell to the basement membrane

Question 39

what is the cilia structure?

Answer 39

9+2 structure of microtubules with a central doublet

Question 40

non-motile cilia have no central doublet and just the ring of 9 microtubules T or F

Answer 40

true

Question 41

what does type 1 collagen do?

Answer 41

resists tension, multiple triple helices bound together to form fibrils, and fibrils are organized to form fibers Major collagen type in dense CT and bone

Question 42

what does type II collagen do?

Answer 42

smaller fibrils with less organized orientation than dense regular tissue ▪ Major component of cartilage - mainly resists pressure and absorbs shock

Question 43

what does type II collagen do?

Answer 43

reticular fibres ▪ Major component of loose connective tissue

Question 44

what are Type I, II, and III collagens are known as

Answer 44

fibrillar collagen

Question 45

what does type IV collagen do?

Answer 45

forms the basement membrane that connects epithelial and connective tissue layers ▪ Forms a sort of cross-linked "net" with laminin (glycoprotein) and proteoglycans interspersed within it

Question 46

what are the 2 major components of the ground substance

Answer 46

multi-adhesive glycoproteins and proteoglycans

Question 47

what are the 3 part structure of proteoglycans

Answer 47

○ A very long, linear polymer of hyaluronic acid (a GAG) ○ Linking proteins attached to the hyaluronic acid polymer ○ Shorter GAG chains attached to the linking proteins

Question 48

atopic dermatitis

Answer 48

* Typical symptoms and signs: ○ Itchy papules and plaques that can become excoriated with scratching ○ Distributed over the extensor surfaces, face, and scalp ○ Worsen in response to allergen exposure * Highly heritable – children of parents with atopic dermatitis have a 50% chance of developing the disorder ○ Subtle abnormalities in filaggrin impair the ability of the more apical strata to retain the moisture of the skin ○ Tight junction changes to more permeable types decrease the barrier function of the skin

Question 49

celiac disease

Answer 49

* A common immune-mediated disorder – individuals mount an immune response to a component of gluten (known as gliadin)