Ma - Epithelium

Front 1

epithelia cover outer surfaces and line inner surfaces (cover all free surfaces) thruout the body except in what 2 places?

Back 1

1) synovial joint cavities
2) anterior surface of the iris

Front 2

Places where epithilium lies and specific organs/body parts with each surface (6)

Back 2

1) Exterior Surfaces of the body (skin) - mesothelium
2) Internal Closed Cavities of the body (abdominal, thoracic and pericardial)
3) those Body Tubes that communicate w/ the exterior (gastrointestinal, respiratory, and genitourinary tracts)
4) the Glands, both exocrine (sweat, saliva, liver, overall fluid) and endocrine (thyroid, adrenal, overall hormones)
5) the Vascular System
6) the Receptors of Certain Sensory Organs - taste buds, olfactory epithelium, retina, auditory/vestibular system (aka Neuroepithelium)

Front 3

An epithelium may have any of several functions, depending on its location in the body (5)

Back 3

1) Protection - skin, portions of GI system (ex. esophagus w/abrasions from sharp foods)
2) Selective Barrier to facilitate or inhibit Exchange of substances -skin, capillaries, lung alveoli, urinary bladder
3) Secretion (gi tract, glands)
4) Absorption (intestine - nutrients)
5) Sensory Reception - neuroepithelium of sensory organs, ex. eye, ear, olfactory, taste)

Front 4

In general, an Epithelium May Be Viewed As A...(select from previous card)

Back 4

...A SELECTIVE BARRIER capable of facilitating or inhibiting the passage of specific substances between its free surface and the udnerlying CT. Thus, any substance that enters or is discharged from the body will usually pass THROUGH the epithelial cells, not between them.

Front 5

Extracellular elements between epithelium?

Back 5

Epithelium is composed of one or more layers of tightly connected cells which have NO EXTRACELLULAR ELEMENTS BETWEEN THEM; arranged as SHEETS OF CELLS that cover surfaces

Front 6

Any contact w/ adjacent cells?

Back 6

Epithelium has SPECIALIZED CONTACT BETWEEN ADJACENT CELLS which hold them tightly together and which allow communication btw cells

Front 7

Polarity of epithelium? Adhesiveness of what side of epithelium to what

Back 7

-Is functionally and morphologically Polarized.
-Has one free, or apical (top), surface which faces an internal or external space and is Non-Adhesive
-The opposite, or basal surface, adjoins the underlying CT and is adherent to the basement membrane

Front 8

Apical and Basal Domains, Lateral Domains formed by what

Back 8

Functionally distinct plasma membrane proteins and lipids exist on the apical and basal surfaces, forming distince Apical and Basal Domains, which are separated by the Lateral Domain

Front 9

How does epithelium receive its nutrients and how is epithelium renewed

Back 9

It is AVASCULAR and gets its nutrients by diffusion from vascular elements (blood vessel/capillaries) present in the underlying CT.
It is renewed by the mitotic dividsion of Stem Cells in response to normal wear and tear or after injury since they are very active

Front 10

Where is simple squamous found (3) and functions (2)

Back 10

Found in:
1) Lining of the vascular system (Endothelium)
2) Lining of peritoneal, pleural, and pericardial cavities (Mesothelium)
3) Pulmonary Alveoli

Functions:
1) Barrier Exchange
2) Lubrication

Front 11

Where is simple cuboidal found (3) and functions (3)

Back 11

Found in:
1) Proximal and Distal Convoluted Tubules of Kidney
2) Glandular Ducts - ducts in exocrine glands
3) Ovarian Surface (germinal epithelium)

Functions:
1) Absorption
2) Secretion
3) Barrier

Front 12

Where is simple columnar found (4) and functions (2)

Back 12

Found in:
1) Stomach
2) Small Intestines
3) Large Intestines/Colon
4) Gall Bladder

Functions:
1) Absorption
2) Secretion

Front 13

Where is stratified squamous found (4) and functions (2)

Back 13

Found in:
1) Vagina
2) Oral Cavity
3) Esophagus (Non-Keratinized)
4) Skin/Epidermis and Fingernails (and parts of oral cavity) are classified as Stratified Squamous, Keratinized Epithelium - keratin has dead cells, no nuclei, full of keratin

Functions:
1) Barrier
2) Protection

Front 14

Where is stratified cuboidal found (2) and functions (2)

Back 14

Found in:
1) Sweat Gland Ducts
2) Large Ducts of Exocrine Glands

Functions:
1) Barrier
2) Conduit - a layer through which things are being transported

Front 15

Where is stratified columnar found 3) and functions (2)

Back 15

Found in:
1) Male urethra
2) Conjunctiva (eye)
3) Largest excretory ducts of exocrine glands

Functions:
1) Barrier
2) Conduit

Front 16

Where is pseudostratified epithelium found (5) and functions (3) and its description

Back 16

Found in:
1) Trachea
2) Bronchii
In these 2, its further described as Pseudostratified, Ciliated, Columnar Epithelium w/Goblet Cells ("Respiratory Epithelium)
3) Epididymis
4) Ductus Deferens
In these 2, its described as Pseudostratified, Columnar Epithelium w/ Sterocilia
5) Olfactory Epithelium
Described as a Neuroepithelium w/ long modified cilia

Has the appearance of being stratified, but all cells rest on the basement membrane, so it really is a SIMPLE epithelium.

Functions:
1) Secretion
2) Absorption
3) Conduit

Front 17

Where is transitional epithelium found (4) and functions (2) and description

Back 17

A truly STRATIFIED epithelium. Has a pillowy appearnce on the surface layer which varies with the degree of distension of the structure being examined.

Found in:
1) Ureter
2) Urethra
3) Urinary Bladder
4) Renal Calyces

Functions:
1) Barrier - so urine stays where it is
2) Distensible properties

Front 18

Where are neuroepithelial cells found (4) and functions (1)

Back 18

Found in:
1) Taste buds
2) Olfactory epithelium
3) Retina (rods and cones)
4) Inner ear (sensory hair lines)

Function:
1) Specialized Sensory Functions

Front 19

Where is myoepithelial cells found (1) and functions (1) and description

Back 19

Myoepthelial cells are branched, stellate cells containing actin filaments. They are CONTRACTILE and help to expel the contents of some exocrine glands, which is where they are found

Front 20

What are glandular epithelium cells specialized to make?
Where is their product stored?
What triggers the release of this product?

Back 20

Specialized to manufacture and secrete proteins, lipids or complexes of carbohydrates and proteins

Secretory product is usually stored in membrane-bound vesicles (Secretory Granules)

Release is mediated by hormones or neural signaling/chemical messengers

Front 21

Two main types of glandular epithelia (glands) and their secretions and where its secreted

Back 21

Endocrine glands – No ducts; secretory products (hormones) enter blood stream or affect nearby cells

Exocrine glands – secrete onto an epithelial surface, usually via tubular ducts (except in the case of Unicellular Glands)

Front 22

Unicellular Glands - have what type of cells to secrete what, where are these cells found, function of the cells' secretion

Back 22

-Have Goblet Cells that are specialized to synthesize and secrete Mucin, which upon hydration forms a lubricating solution called Mucus.
-The cells are scattered among the epithelial columnar cells of the intestine and the respiratory system.
-Their mucus secretions cover the apical surfaces of the adjacent epithelial cells to lubricate and protect the epithelium. Lymphocytes can also be found next to them, but do not confuse them for goblet cells

Front 23

Multicellular Glands - when do they develop, what 2 portions do they have and what does each portion do

Back 23

-Develop when epithelia invade the underlying CT
-Usually consist of a Secretory Portion that synthesizes the secretion
-The Duct Portion trasports the secretion to the surface.

Front 24

Multicellular Glands - Classifications (4)

Back 24

1) If the duct is unbranched, the gland is called Simple
2) If the duct is branched, the gland is called Compound
3) If the secretory portion is shaped like a tube, the gland is Tubular
4) If it is flasklike it is Alveolar (aka Acinar).

-various comos of duct and secretory shapes are found in body. thus, glands may be simple straight tubular, simple coiled tubular, simple alveolar, etc. compound tubuloalveolar glands can have BOTH tubular and alveolar secretory units.

Front 25

Some, but not all, exocrine glands contain serious or mucous cells, or both.
What do serous cells synthesize and secrete, where are these cells found (2)

Back 25

-Synthesize and secrete proteins from RER w/ numerous polyribosomes located near the base of cell and secretory granules accumulate at the apical surface.
-Serous cells are present in the exocrine pancreas and in salivary glands.

Front 26

What do Mucus-Secreting cells synthesize and secrete and where are they found (3)

Back 26

-Synthesize and secrete glycoproteins called Muscins.
-Mucous cells are present in salivary glands, the respiratory system and the GI tract. Have an irregularly shaped and basally-located nucleus.

Front 27

3 Mechanisms (Secretions) for the release of secretory products

Back 27

1)Merocrine Secretion
2) Apocrine Secretion
3) Holocrine Secretion

Front 28

Merocrine Secretion - when does it occur in which gland(s) does this secretion occur?

Back 28

-Occurs when the membrane of the secretory granule fuses with the cell membrane (Exocytosis); no loss of other cellular material
-Occurs IN MOST exocrine and endocrine glands

Front 29

Apocrine Secretion - when does it occur, in what gland

Back 29

-Occurs when the secretory product is discharged along with parts of the cytoplasm and plasma membrane
-Mammary gland uses it for lipid component of milk

Front 30

Holocrine secretion - when does it occur, in what gland

Back 30

-Occurs when the product of secretion is shed with the entire cell
-Sebaceous glands of the skin

Front 31

Myoepithelial cells role in secretion

Back 31

-Contain contractile elements (actin and myosin) within the cytoplasm of their processes and communicate via gap junctions to provide coordinated contraction that squeezes out the contents of secretory portion of the gland following nervous or hormonal stimulation

Front 32

Apical Surface Specializations (3) and their functions

Back 32

1) Cilia - motile, beat synchronously in a particular direction so as to propel materials upward. Surrounded by 9 pairs + 2 microtubules. They are anchored to basal bodies in the apical cytoplasm, Kartagener’s syndrome - disorder caused by a defect in the action of the tiny hairs (cilia) lining the respiratory tract.
2) Microvilli - Maximize apical surface area, non-motile, striated brush border, contain a core of microfilaments (actin) that provide rigidity, the microfilaments anchored to the plasma membrane extend into apical cytoplasm where they insert onto network of actin and myosin II filaments called the Terminal Web
3) Sterocilia - not cilia, is branched microvilli present only in the epididymus, vas deferens, and sensory (hair) cells of ear, flexible but non-motile, cytoplasmic bridges, increase apical surface area, resorption of fluids secreted by testis, integral part of sensory apparatus.

Front 33

The lateral domains of epithelial cells are the sites of various functionally and morphologically distinct...
And what are the functions of these things (3)

Back 33

...Intercellular Junctions which are
1) responsible for the ADHERENCE of adjoining cells
2) provide a BARRIER FOR THE DIFFUSION of substances between the cells
3) allow for COMMUNICATION between cells.

Front 34

Descriptions of Intercellular Junctions (4)

Back 34

1)Zonula Occludens
2) Zonula Adherens
3) Macula Adherens
4) Gap Junctions

Front 35

Zonula Occludens - primary function, consists of?, occludins and claudins, proteins found here and what do they do (2), pathogenic agents

Back 35

-Primarily a barrier device, also referred to as Tight Junction, keeps paracellular pathways closed
-Consists of narrow band that Completely Encircles the cell (zonula = belt)
-Outer leaflets of the plasma membranes of adjoined cells appear to converge and fuse at multiple sites via transmembrane junctional proteins (Occludins and Claudins)
-ZO-1, ZO-2, ZO-3 proteins bind the cytoplasmic portion of the junctional proteins and they bind occludins and claudins to the actin cytoskeleton.
-Pathogenic agents such a Cholera Toxin act on the ZO proteins ot cause junctional permeability

Front 36

Zonula Adherens - primary function, proteins found here (3) and their function, transmembrane adhesion molecule found here and its function

Back 36

-Is an Adhesive Device located beneath zonula occludens, also form a belt around each epithelial cell
-On the cytoplasmic side of the junction, a dense plaque is formed by the protein Catenin and actin-binding proteins (Alpha-Actinin and Vinculin) which bind to the Actin Filaments of the terminal web
-Intercellular space present that is filled w/ a transmembrane ahdesion molecule (E-Cadherin) that binds to Ca++, which is essential to matinain junctional integrity

Front 37

Macula Adherens - primary function, what is found here, transmembrane adhesive glycoproteins (2),

Back 37

-An Adhesive Device that is also referred to as a Desmosome, effectively link the cytoskeletons of neighboring cells
-On the cytoplasmic side of the plasma membrane is a dense Plaque consisting of specialized proteins in which Intermediate Filaments (tonofilaments) are anchored
-Intercellular space between 2 desmosomes is filled by transmembrane adhesive glycoproteins called Desmocollins and Desmogleins.

Front 38

Hemidesmosomes - are what, located on what type of cells, anchor what, attach cell via what?

Back 38

-Half desmosomes located on basal plasmalemma of epithelial cells that are subjected to a lot of abrasion (skin, cornea, esophagus, vagina)
-Anchor cytoplasmic intermediate filaments
-Attach the cell to the basement membrane via transmembrane proteins called INTEGRINS.
-However, MOST epithelial cells attach to the basement membrane by simpler structures called Focal Adhesions that anchor cytoskeletal Actin Filaments to the basement membrane

Front 39

Junctional Complex

Back 39

zonula occludens, zonula adherens, macula adherens are collectively called the junctional complex aka the Terminal Bar in the LM

Front 40

Gap Junctions - primary function, occur where, gaps bridged by what unit, what is unit composed of, what causes closure of gap junctions, cell-to-cell communication via?

Back 40

-are Non-Adhesive and allow for Communication between neighboring epithelial cells
-Can occur anywhere along the lateral membranes of epithelial cells.
-Gap is bridged at intervals by functional units called Connexons
-Each connexon is formed by a group of 6 individual Connexin Protein units in each of the apposed cell membranes.
-High intracellular Ca++ concentrations cause closure of gap junctions - mechanism unknown!
-cell-to-cell communication via hydrophilic pores

Front 41

Lateral and Basal Surface Folds - what are they, what do they lead to, found where (5)

Back 41

-Tortuous infoldings are interdigitations between the lateral membranes of adjoining epithelial cells are especially PROMINENT IN EPITHELIA THAT TRANSPORT FLUID RAPIDLY, ex. in the intestine, gallbladder and kidney.
-The lateral cell surface area is thus increased, allowing more area for active transport of sodium ions into intercellular space and for water to follow the osmotic gradient.
-Other fluid transporting epithelia such as the proximal and distal kidney tubules and the straited ducts of the salivary glands have infoldings along their basal surfaces.

Front 42

Functions of BM (7)

Back 42

1 Structural attachment of epithelium to underlying
connective tissue

2 Separates epithelium from connective tissue

3 Selective permeability barrier in some areas
(kidney glomerulus)

4 Development of epithelial polarity and cell shape

5 Can organize proteins within epithelial plasma membranes
to affect signal transduction

6 Regulation of proliferation & differentiation (growth factor
storage)

7 Migratory substrate for epithelial cells during development
and repair

Front 43

2 components of BM

Back 43

Basal Lamina and Reticular Lamina

Front 44

Basal Lamina - secreted by what, contains what which is separated by what

Back 44

-Secreted by epithelium
-Consists of an electron-dense band called the Lamina Densa, which is separated from the epithelium by an electron-lucent layer called the Lamina Lucida
-The lamina densa contains laminin, fibronectin, type IV collagen and heparin sulfate proteoglycans.
-Laminin and fibronectin are attached to cell membrane by integrins

Front 45

Reticular Lamina - secreted by what, composed of what, basal lamina attached to it how

Back 45

-secreted by underlying CT
-composed of Reticular Fibers, which are fibrils of Type III Collagen
-Anchoring Fibers that consist of Type VII Collagen attach the basal lamina to the reticular lamina