Epithelium

Question 1

What are the five levels of organization within the body?

Answer 1

cell–>tissue–>organ–>system–>body

cell: basic functional unit of the body
tissue: a collection of cells and material between cells that perform a specialized function
organ: a structure or mass formed by basic tissues to perform specialized functions
system: a group of organs that work together to perform specialized functions

Question 2

The four primary tissues and their functions are:

Answer 2

1) epithelium: covering and lining surfaces and secretion
2) connective tissue: support
3) muscle: contraction
4) nervous tissue: impulse conduction

Question 3

The three germ layers of epithelium are:

Answer 3

ectoderm, mesoderm, endoderm

Question 4

The seven different functions of epithelium are:

Answer 4

1) Protection: physical, chemical, metabolic
2) Transcellular support: active and passive
3) Secretion: mucous, hormones, enzymes, cytokines
4) Absorption: nutrients, other materials
5) Selective Permeability: between epithelial cells
6) Sensory Detection: taste, hearing, sight
7) Contraction: myoepithelial cells

Question 5

3 characteristics of epithelium:

Answer 5

1) composed entirely of cells
2) avascular (no blood vessels)
3) polarity (apical, basal, lateral)

Question 6

3 physical arrangements of epithelium:

Answer 6

1) sheets of tightly bound cells (membrane epithelium)
2) glands
3) non-secretory individual or small clusters of cells

Question 7

Criteria for classifying epithelium:

Answer 7

1) number of layers
2) shapes of cells
3) Special modifications

Question 8

What are the different types of layers?

Answer 8

simple, stratified, pseudostratified

Question 9

What are the different shapes of cells?

Answer 9

Cell shape of epithelium is classified by the surface layer:

squamous (flat), cuboidal (square), columnar (rectangular)

Question 10

What are the different types of specialized functions?

Answer 10

1) apical cell membrane
a) kinocilia: long, mobile projections that allow movement
b) microvilli: increases surface area; short projections (brush border)
c) stereocilia: increases surface area; long, non-mobile projections
2) basal cell membrane
basal infoldings: invaginations in basal cell membrane
3) cytoplasm
keratinization: only occurs in skin; deposition of proteinaceous filaments

Question 11

In transitional epithelium…

Answer 11

stratified epithelium, shape of surface cells are variable, can stretch without breaking cell to cell attachment

Question 12

The apical surface of the cell faces the ________, and the basal surface attaches to the ________ ___________.

Answer 12

lumen, basal membrane

Question 13

_______ _________ attaches cells together and was later identified as junctional complexes.

Answer 13

terminal bars

Question 14

What is another name for a desmosome?

Answer 14

macula adherens

Question 15

What are the components of a junctional complex?

Answer 15

zonula occludens, zonula adherens, macula adherens

Question 16

What are gap junctions?

Answer 16

channels that allow the passage of material and the communication between cells

Question 17

________ ________ holds cells together and was later identified as desmosomes.

Answer 17

intercellular bridges

Question 18

What does the basement membrane do?

Answer 18

acts as glue to hold epithelial tissues to connective tissue; filtration; directs cell migration during healing

Question 19

What are the two components of the basal membrane?

Answer 19

basal lamina (produced by epithelial cells) and lamina relicularis (lamina fibroreticularis—-> produced by fibroblasts)

Question 20

What are glands, and where do they originate?

Answer 20

One or more specialized cells that elaborate secretory products (material not related to their ordinary metabolic needs).
They originate from epithelial cells and are formed by projections of epithelium at the surface of a body into underlying mesoderm.

Question 21

What are the two components of glands?

Answer 21

1) parenchyma: functional components

2) stroma: supporting or structural components

Question 22

List 6 criteria for classifying glands:

Answer 22

1) presence or absence of duct
2) number of secretory cells
3) nature of secretory product of exocrine glands
4) mode of secretion of product of exocrine glands
5) collective shapes of groups of secretory cells of exocrine glands
6) distance that endocrine secretory product must travel

Question 23

Differentiate endocrine and exocrine glands

Answer 23

Endocrine glands have no duct and release secretory products into blood vessels or tissue fluid for transport to other locations in the body.
Exocrine glands HAVE a duct that transport secretory product to surface.

Question 24

Differentiate between unicellular and multicellular glands.

Answer 24

Unicellular glands only have 1 cell (i.e. goblet cell), and multicellular glands have 2 or more cells (i.e. salivary).

Question 25

Name four and describe different natures of the secretory products of exocrine glands.

Answer 25

1) serous: watery, protein rich
2) mucous: viscous, slippery, rich in sugars
3) mixed: contains serous and mucous components
4) sebaceous: lipids

Question 26

Name and describe the three different modes of secretion of exocrine glands.

Answer 26

1) merocrine: released from secretory granule with no loss of cytoplasm
2) apocrine: small portion of apical cytoplasm pinched off with secretory product
3) holocrine: entire cell released as secretory product

Question 27

Name the three shapes of exocrine glands and be able to recognize.

Answer 27

tubular, acinar, alveolar

Question 28

Differentiate the three different types of secretory distances.

Answer 28

1) autocrine: secretory product directly acts on same cell
2) paracrine: secretory product acts on adjacent cell
3) endocrine: secretory product travels via vasculature and acts on distant cells

Question 29

Exocrine glands are classified as either:

Answer 29

“simple” if duct is unbranched or “compound” if the duct does branch

Question 30

What are the types of exocrine glands dependant on?

Answer 30

arrangement of ducts and secretory cells

Question 31

Differentiate between a lobe and a lobule.

Answer 31

A lobule is a group of parenchyma surrounded by stroma; a lobe is a group of many lobules.

Question 32

Go through the heirarchy of exocrine glands:

Answer 32

secretory cells—>intercalated duct—>intralobular duct—>interlobular duct—>lobular duct—>main duct

Question 33

What cells assist with the movement of product out of exocrine glands?

Answer 33

myoepithelial cells