Epithelium

Question 1

Parenchyma-active portion

Answer 1

fxnal
epithelial portion of organs
cells of an organ that provide fxn (hepatocyte)

Question 2

Stroma-organization aspect

Answer 2

supporting CT of organ

CT serves as support, structure and protection of epithelial cells of the organ

Question 3

Fxns of Epithelium

Answer 3

Covering/lining surfaces-skin, mucus membranes, respiratory tract, blood vessels
Absorption-intestines
Secretion-glands (salivary, intestinal, endocrine)
Sensation- neuroepithelium
Contractility- myoepithelium of sweat, salivary, mammary glands

Question 4

Types of Epithelium: Shape

Answer 4

Squamous
Cuboidal
Columnar

Question 5

Types of Epithelium: Number of layers

Answer 5

Simple
Stratified
Pseudostratified

Question 6

Types of Epithelium: Specializations

Answer 6

Cilia
Microvilli
Goblet cells
Kertinization

Question 7

Types of Epithelium: Fxn

Answer 7

Covering epithelia
Glandular epithelia
Secretory cells

Question 8

Structure of Epithelium

Answer 8

All epithelial cells rest on a ECM called basal lamina (basement membrane)

Question 9

Basal Lamina

Answer 9

Separates epithelium from support tissues (CT beneath)

Identifies orientation of cells above

Question 10

Fxn of basal lamina

Answer 10

• Supports the epithelial cells above
• Acts as a diffusion barrier w/pores that are semi-permeable
• Controls cell organization and differentiation
• Pathway for cell migration during development and healing

Question 11

Basal Lamina Components

Answer 11

Type IV collagen, laminin, heparan sulfate, fibronectin, CHO

—Composition of the basal lamina varies among tissue types based on the fxn of the particular tissues

Question 12

Simple Squamous

Answer 12

Lungs
Lining of vessels
Serous lining of cavities
Facilitate mvmt of viscera; Active & Passive transport of substances

Question 13

Simple Cuboidal

Answer 13

Covering of ovary, thyroid gland, kidney
Covering, secretion
Molecule Transport: active & passive

Question 14

Simple Columnar

Answer 14

Lining of intestine, gall bladder

Protection, lubrication, absorption, secretion

Question 15

Pseudo-stratified Columnar/Cuboidal

Answer 15

Lining of trachea, bronchi, nasal cavity, ducts of male repro.
Protection, secretion,absorption, cilia-mediated transport (trap air-borne particles)
Nuceli are at different levels–cilia;goblet cells

Question 16

Keratinized: stratified squamous

Answer 16

Epidermis-multiple layers of squamous cells
Protection against friction, prevents water loss (dehydration)
no nuclei–deepest layer cuboidal shaped

Question 17

Non-keratinized: stratified

Answer 17

Mouth, esophagus, vagina, anal canal
Protection-areas of repeated forces/friction, secretion, prevents water loss
nuceli present

Question 18

Cuboidal: stratified

Answer 18

Sweat glands, ovarian follicles

Protection, secretion

Question 19

Transitional: stratified

Answer 19

Bladder, ureters

Protection, distensibility

Question 20

Columnar: stratified

Answer 20

Conjunctiva of eyes

Protection–mucus secreting

Question 21

Goblet Cells

Answer 21

• Mucus secreting cells of epithelial tissues

- Found in intestinal and respiratory tracts

Question 22

Facet cells

Answer 22

change shape according to degree of bladder distention (cuboidal to squamous (closer to surface))

Question 23

Epithelial Cells: Innervation

Answer 23

Rich supply of capillary blood and sensory nerve endings from nerve plexuses in the CT (lamina propria-basement membrane)

Question 24

Renewal of Epithelial Cells

Answer 24

renewed continuously by means of mitotic activity

Rate of renewal is variable

Question 25

Rate of renewal rapid vs slow

Answer 25

Rapid: intestinal epithelial cells replaced each week; skin replaced in a month Slow: liver and pancreas (monthS)

Question 26

Communicating Jxns= Gap Jxns

Answer 26

control passage of chemical and electrical signals from cell to cell allow easy exchange of ions and small molecules--and pass b/w ells w/o reaching the extracellular fluid IMPORTANT FOR APs to be coordinated, synchronized

Question 27

Occluding Jxns=tight jxns

Answer 27

seals cells together in a sheet-like formation | prevents mvmt of molecules b/w cells

Question 28

Anchoring Jxns

Answer 28

Desmosomes; Hemidesmosomes | -Attach cells to other cells or to extracellular matrix

Question 29

Gap Jxns Characteristics

Answer 29

Connexon Permeability of the gap is controlled by individual connexins Cells are able to control permeability of these jxns Most wide spread cell jxns

Question 30

Connexon

Answer 30

pair of 6-protein connexons span lipid bilayer of adjacent cells each protein of connexon is called CONNEXIN

Question 31

Tight Jxns-Occulding Jxns Structure and Fxn

Answer 31

Jxn forms a "band" completely encircling adjacent cells Membranes "fuse" preventing material from moving b/w cells Main fxn is to prevent diffusion b/w cells

Question 32

Why are tight jxns important in epithelial tissues

Answer 32

Skin-provides waterproof barrier | GI tract-prevents molecules from moving out of the gut lumen b/w nutrient absorbing cells

Question 33

Anchoring Jxns-Desmosomes

Answer 33

Serve as anchoring jxn to bind cells together Widely distributed in animal tissues Attachment sites for intermediate filaments

Question 34

Make-up of Desmosomes

Answer 34

- intracellular attachment protein that connects desmosome to intermediate filament in cytoplasm - transmembrane linker protein (cadherin)

Question 35

Hemidesmosomes

Answer 35

bind cells to basal lamina