Histology Quiz 1- Epithelial Tissue

Front 1

tissues: definition

Back 1

organized aggregation of cells with same structure, same origin, perform same function

Front 2

4 basic types of tissues

Back 2

1.epithelial
2.connective
3.muscle
4.nervous

Front 3

3 main locations of epithelial tissue

Back 3

1.cover exterior surfaces (barrier epithelium)
2.line internal cavities (barrier epithelium
3.form secretory portion of glands and their ducts (glandular epithelium)

Front 4

main structural difference of epithelial tissue

Back 4

exposed free surface in external body surface (skin) and luminal surface (linine of the intestine) --> much adaptation to deal with environment

Front 5

cellular composition of epithelial tissue & key difference

Back 5

closley aggregated cells, adhesion between cells is very strong (strongest of all tissues)

key difference: little to no extracellular matrix

Front 6

Epithelial tissue is vascular or avascular?

Back 6

avascular- no blood supply.
get rid of waste via diffusion because cells line the walls of blood vessels``

Front 7

morphological polarity

Back 7

Epithelial cells have distinctive orientation. Possible to identify 3 main surfaces

Front 8

3 main surfaces present in epithelial cell

Back 8

1.apical
2. lateral
3. basal

Front 9

apical domain

Back 9

forms the external or luminal surface of the cell

Front 10

3 modifications found on apical surface

Back 10

1.microvilli
2. stereocilia
3. cilia

Front 11

function and location of microvilli

Back 11

function- increase surface area
location- where absorption is important, small intestine or kidney

Front 12

3 characteristics of microvilli

Back 12

1. size- 0.01 µm
2. actin core
3.amorphous apex formed by villin

Front 13

villin

Back 13

protein into which actin filaments are anchored by myosin I

Front 14

actin core

Back 14

actin filaments bound together by fimbrin and fascin, anchored into membrane by myosin I

Front 15

fimbrin and fascin

Back 15

actin-binding protiens

Front 16

myosin I

Back 16

latera anchoring protien, attaches actin filaments to membrane

Front 17

stereocilia vs cilia

Back 17

Stereocilia are modified microvilli. They are NOT RELATED to cilia.

Front 18

stereocilia

Back 18

long, sometimes branching projections of actin filaments of microvilli's core.2

Front 19

2 roles of stereocilia

Back 19

1. epididymis-absorption of fluid
2. inner ear cochlea- sensory receptors

Front 20

function and location of cilia

Back 20

function-move substances along the surface of epithelium (mucus)
location-areas where transport is necessary (respiratory tract or ovum

Front 21

axoneme

Back 21

20 pairs of microtbles forming the core of a cillium

Front 22

basal body

Back 22

centriole, attached to base of cilium, formed by 9 triplets of microtubules WITHOUT A CENTRAL PAIR

Front 23

primary ciliary dyskinesia

Back 23

(immotile ciliary syndrome)
genetic defects ---> maformation of the skeleton of cilia --->uncoordinated or absent ciliary beating.

dextrocardia, impaired development of sinuses, no mucus removal/infections, infertility

Front 24

lateral domain

Back 24

characterized by the presence of cell junctions that allow the tissue to function as a whole

Front 25

3 major classes of cellular junctions

Back 25

1.occluding
2.anchoring
3.communicating

Front 26

terminal bars

Back 26

many junctions occuring together ina group or complex, visualized in light microscope

Front 27

occluding junctions

Back 27

(tight junctions)
mostly present toward apical portion, represented by a single type, zonula occludens

Front 28

zona occludens

Back 28

belt-like junction formed by sealing starnds of trasmembrane proteins that bind membranes of two adjacent cells

virtually impermeable

main function is to prevent diffusion

Front 29

What type of cells are occluding/tight junctions found in?

Back 29

Cells with a secretory role (stomach epithelia) or absorptive role (kidney tubule cells)

Front 30

How does the zona occludens preent diffusion?

Back 30

By blocking the paracellular pathway.

Front 31

anchoring junction

Back 31

connect cytoskeleton of one cell to that of an adjacent cell or extracellular matric
designed to provide stability and mechanical strength to the tissue and allow it to function as one unit

4 types: 2 in lateral, 2 in basal

Front 32

4 types of anchoring junctions

Back 32

1. zonula adherens (lateral)
2. macula adherens (lateral)
3. focal contact (basal)
4. hemidesmosome (basal)

Front 33

zonula = x

macula = y

Back 33

zonula = belt

macula = spot

Front 34

zonula adherens

Back 34

belt like junction that connects actin filaments of one cell to actin filaments of another cell

Front 35

macula adherens

Back 35

(desmosome)
spot-like junction that connects intermediate filaments of two cells (stronger because intermediate filaments >> actin filaments)

Front 36

composition of zonula adherens

Back 36

composed of actin, actin binding protein viniculin, peripheral protein which links viniculin to transmembrane protein cadherin, and cadherin which binds to itself on the next cell.

Front 37

composition of macula adherens

Back 37

composed of intermediate filaments that go through an intracellular plaque made of desmoplakin, and transmembrane cadherin proteins

Front 38

pemphigus

Back 38

condition in which body produces too many antibodies to proteins forming desmosome junctions---> poor adhesion--> space finns up and creates blister in mouth and skin

Front 39

communicating junctions

Back 39

(gap junctions)
allow for diffusion of small molecules and ions between cytoplasms of adjacent cells
allow communication between cells and have a role in the control of cell proliferation and differentiation

Front 40

composition of communicating/gap junctions

Back 40

intercellular channels- allow for diffusion. composed of a pair of connexons allinghed with each other

Front 41

connexon

Back 41

forms intercellular channel in gap junctions

made up of 6 protein subunits called connexins

Front 42

Gap junctions typically occul in groups called ___________.

Back 42

patches

Front 43

4 common location of gap junctions

Back 43

1. epithelium
2. cardiac muscle
3. smooth muscle
4. embryonic tissue

Front 44

basal domain

Back 44

epithelial cell domain which faces the basement membrane and is important for interactions with the underlying (connective) tissue

Front 45

basement membrane

Back 45

seperates epithelium from the underlying connective tissue, formed by 2 layers

Front 46

2 layers of basement membrane

Back 46

1. basal lamina
2. reticular lamina

Front 47

basal lamina

Back 47

most external layer of the basement membrane, belongs to the epithelium
composed of sheets of collagen type IV and laminin

Front 48

reticular lamina

Back 48

deeper layer of basement membrane, belongs to connective tissue
composed of thin collagen fibers

Front 49

2 types of anchoring junctions in the basal domain

Back 49

1.focal adhesions
2. hemidesmosomes

Front 50

focal adhesions

Back 50

(focal contacts)
attach actin cytoskeleton of a cell to the extracellular matrix

Front 51

key difference in composition of basal domain and lateral domain anchoring junctions

Back 51

lateral = cadherin transmembrane protein

basal= integrin transmembrane protein

Front 52

integrin is Ca 2+ _____________

Back 52

independent

Front 53

composition of focal adhesions

Back 53

microfilaments attach to actin binding protiein vinculin,peripheral protein talin connectis vinculin to the integrin transmembrane protein.

Front 54

hemidesmosome

Back 54

connects intermediate filaments in cell cytoskeleton to the extracellular matrix

Front 55

key difference in hemidesmosome vs desmosome

Back 55

intermediate filaments go through a desmosome.

intermediate filaments end on plaque in hemidesmosome.

Front 56

composition of hemidesmosome

Back 56

intermediate filaments end on intracellular plaque made of desmoplakin, integrin transmembrane proteins attach to the extracellular proteins

Front 57

3 ways to classify epithelial tissue

Back 57

1.By layers
2. By cell shape
3. By apical cell surface modifications

Front 58

simple

Back 58

single cell layer in the epithelium

Front 59

pseudostratified

Back 59

all cells of the tissue rest on the basement membrane, but not
all of them reach the surface.

Front 60

stratified

Back 60

more than one layer of cells in the epithelium.

Front 61

squamous

Back 61

flat cells

Front 62

cuboidal

Back 62

if the transverse diameter of the cell is roughly equal to the cell height

Front 63

columnar

Back 63

if the cell height is considerably greater than the transverse diameter.

Front 64

ciliated vs non-ciliated

Back 64

cilia present vs cilia not present, even if microvilli or stereocilia are

Front 65

location of simple squamous epithelium

Back 65

lining of the cardiovasuclar sytem, body cavities, parietal layer of the Bowman's capsule of the kidney, alveoli of the lung

Front 66

2 major functions of simple squamous epithelium

Back 66

1. barrier
2. diffusion of oxygen and carbon dioxide

Front 67

endothelium

Back 67

special type of simple squamous epithelium that lines inner walls of blood vessels and heart

Front 68

mesothelium

Back 68

special type of simple squamous epithelium that covers internal organs within the plueral, pericardial and peritoneal cavities.

Front 69

common locations of simple cuboidal epithelium

Back 69

walls of ducts of various glands, kidney tubules, germinal epithelium of the ovary, thyrouid follicles

Front 70

3 main functions of simple cuboidal epithelium

Back 70

1.barrier (ducts)
2.secretion (thyroid)
3.absoption (kidney)

Front 71

Individual microvilli cannot be seen in the light microscope but densely packed microvilli form a thin layer called the ______________.

Back 71

striated or microvillar border

Front 72

non-ciliated simple columnar epithelium

Back 72

found in the lining of the GI tract and in the walls of the gallbladder

Front 73

ciliated simple columnar epithelium

Back 73

found in the lining of the oviduct

Front 74

4 main functions of simple columnar epithelium

Back 74

1. absorption
2. secretion
3. lubrication
4. transport (if cilia are present)

Front 75

basal cells

Back 75

bells in psuedostratified columnar epithelium which rest on the basement membrane and serve as the replacement/progenitor cells in this epithelium

Front 76

metaplasia

Back 76

reversible replacement of one differentiated cell type with another mature differentiated cell type

in heavy smokers, normally psuedostratified ciliated columnar epithelium goes to startified squamous non-ciliated.

Front 77

keratinized stratified squamous epithelium

Back 77

characterized by the presence of the dead cornified layer on the surface, found in the epidermis of the skin.

Front 78

non- keratinized stratified squamous epithelium

Back 78

does not have the dead layer of keratin on the surface, found in the beginning of the GI tract (oral cavity, esophagus) and in the female reproductive system (vagina).

Front 79

stratified cuboidal epithelium

Back 79

rather rare, found in ducts of glands, most common in the ducts of sweat glands of the skin

consists of two layers of cells that are cuboidal in shape.

Front 80

2 functions of stratified cuboidal epithelium

Back 80

1. barrier
2. conduit.

Front 81

stratified columnar epithelium,

Back 81

even rarer, can be found in the larger ducts of several glands, including the parotid and submandibular salivary glands. The basal layer of this epithelium is composed of cuboidal cells, while the surface cells are columnar.

Front 82

2 functions of stratified columnar epithelium

Back 82

1. barrier
2. conduit

Front 83

transitional epithelium

Back 83

(urothelium)
restricted to the urinary system (urinary bladder, ureter, and in the pelvis and calyces of the kidney)
cannot be classified as squamous, cuboidal, or columnar. It is composed of multiple layers of cells of different shape. The surface layer often contains large rounded “dome” cells that are often binucleated. The most important feature of the transitional epithelium is its ability to stretch enormously: bladder full= flat
bladder empty= cuboidal

Front 84

glandular epithelium

Back 84

formed as a result of invagination of the epithelial tissue
epithelial cells then start secreting various materials, such as mucins, steroids, etc.

Front 85

endocrine glands

Back 85

secrete their product into the intercellular space or underlying
connective tissue and the product diffuses into blood (NO DUCTS)

Cells within endocrine glands are usually arranged in cords that follow the capillaries that supply the gland.

Front 86

exocrine glands

Back 86

maintain their connection to the originating epithelium and secrete into ducts, or spaces lined with the originating epithelium.

Cells within the exocrine glands are usually arranged into acini or tubules.

Front 87

3 major mechanisms of secretion

Back 87

1. merocrine
2. apocrine
3. holocrine

Front 88

merocrine gland

Back 88

secretory product is delivered in membrane-bound
vesicles to the apical surface, where the vesicles fuse with the plasma membrane to release their content via exocytosis.

Front 89

3 types of merocrine glands

Back 89

1. serous
2. mucous
3. mixed

Front 90

serous glands

Back 90

secrete a thin, watery, protein-rich secretion. The secretory vesicles are small and densely-staining. These cells have better developed rough ER than mucous cells, and consequently their cytoplasm stains more basophilic. The rough ER occupies the basal part of the cell, and as a result the nuclei are shifted towards the middle of the cell. These cells are usually pyramidal in shape and as a result serous acini are rounded in shape. Examples: pancreas and parotid salivary gland.

Front 91

mucous glands

Back 91

produce mucins that consist of long chains of negatively charged carbohydrates attached to a small protein core. Mucins are viscous and are important for lubrication and protection. The secretory granules are large and stain very lightly with hematoxylin and eosin. The rough ER is not well developed. The nuclei are heterochromatic and occupy basal position in the secretory cells of mucous glands. Mucous cells are usually columnar in shape and mucous acini typically have tubular shape. Examples: goblet cells, glands of the soft palate, Brunner’s glands.

Front 92

mixed/ seromucous glands

Back 92

have both serous and mucous cells. Mucous cells form tubules, capped by serous cells that form serous demilunes. Example: submandibular salivary gland.

Front 93

apocrine

Back 93

secretion involves pinching of the apical cytoplasm with the formation of secretory vesicles. This mechanism is found in the mammary gland, where it is responsible for releasing large lipid droplets into milk.

Front 94

holocrine

Back 94

secretion involves the whole cell, rather than its parts. As the cell accumulates the secretory product, it goes through apoptosis (programmed cell death), and both the cellular content and cell debris are released into the lumen of the gland. This type of secretion is typical for sebaceous glands of the skin.