Epithelial Cell Tissue

Question 1

Epithelial Tissue

Answer 1

• Single or multi layered sheet covering every free surface in the body
• Cells are joined by protein junctions which are anchored to a basement membrane
• Polarized: apical and basal surfaces
• where most cancer comes from

Question 2

Connective tissue

Answer 2

Defined by the cell type (which are separated from one another) and the extracellular matrix of which they secrete
ex) Loose/Dense/Blood/Bone

Question 3

Muscle Tissue

Answer 3

ex) Skeletal, smooth, and cardiac
- characterized by abundance of contractile elements
- cellular or functional syntitium

Question 4

Nervous Tissue

Answer 4

Highly excitable cells specialized for transmitting electrical impulses
- neuron: dendrite, cell body, axon, and synapse
- myelin: increases speed of conduction - appears in most tissue preps, with a central dark axon
- Neuroglia - supports cells of the nervous system

Question 5

Epithelial Tissue

Answer 5

Lines all surfaces of the body: external, internal (closed and open)
Polarized:
- apical domain: faces the exterior world lumen or body cavity
- lateral domain: cell junctions, vary for each tissue type
- basal domain: anchored to the basement membrane
- Secretory glands and specialize receptors: smell, taste, hearing, and vision

Question 6

Epitheloid Tissue

Answer 6

Anchored together on a basement membrane but lacks a free surface
ex) Endocrine cells - leydig cells of the testes, beta cells, and alpha cells of the pancreas

Question 7

Function of epithelial tissue

Answer 7

• Protection: stratified squamous
• Absorption: blood passes through the lumen and are absorbed by microvilli (columnar and cuboidal)
• Secretion: all types
• Transport: through cell and surface (lungs, fallopian tubes: cilia moves egg, and pharynx: cilia moves mucous)
• receptors

Question 8

Simple Squamous Epithelium

Answer 8

• One flat layer
• Location: air sacs of lungs and the lining of the heart, blood vessels, and lymphatic vessels
  Function: Allows material to pass through by diffusion and filtration, and secretes lubricating substance
  ex) mesothelium - covers internal organs (has adipocytes - large white outlined by purplish-pink)
  other ex) / endo and pericardium (makes pericardial fluid) / endothelium (signals to blood for clots) / mesothelium (covers entire female-reproductive tract) / outer layer of Bowman’s capsule

Question 9

Simple Cuboidal Epithelium

Answer 9

• One cubed layer
• Location: in ducts and secretory portions of small glands and in kidney tubules
• Function: secretes and absorbs
• Found in: pancreatic ducts and have spherical nuclei/apical surfaces faces the lumen of the duct
  Found in: bronchioles (controlling the conduction of air
  Found in: Liver (hepatocytes): high livers of absorption and secretes hormones/bile salts

Question 10

Simple Columnar Epithelium (ciliated and smooth)

Answer 10

Ciliated Location: Ciliated tissues are in bronchi, uterine tubes, and uterus
Smooth Location: digestive tract and bladder
Function: absorbs and secretes mucous/enzymes
- has goblet cells
- Note: intestines are tubes can be scrunched in pictures
- Cilia help things move

Question 11

Stratified Squamous Epithelium

Answer 11

Location: lining of esophagus, mouth, and vagina
Function: protects against abrasion
Non-keratinized: Vaginal wall, esophagus
Keratinized: skin (thick-no hair and thin - hair)

Question 12

Simple columnar to stratified squamous

Answer 12

• anus to rectum
• stomach to esophagus
• uterus to vaginal wall

Question 13

Stratified cuboidal Epithelium

Answer 13

Location: sweat glands, salivary glands, and mammary glands
Function: protective tissue
- typically two layers

Question 14

Stratified Columnar Epithelium

Answer 14

Location: male urethra and the ducts of some glands
Function: secretes and protects

Question 15

Transitional Epithelium

Answer 15

Location: lines bladder, urethra, and uterus
Function: allows the urinary organs to expand and stretch
- multi-layered
- surface cells are large and dome shaped and will flatten when there is a distention of bladder

Question 16

Pseudo-stratified Epithelium

Answer 16

Location: ciliated tissues lines the trachea and much of the upper respiratory tract
Function: secretes mucous and ciliated tissue moves mucous
- all cells are attached to basement membrane
- goblet cells
ex) epididymis

Question 17

Apical Modifications

Answer 17

Cilia: larger
Microvilli: hazy/disorganized (can only be seen in small intestine/neprons)

Question 18

Microvilli

Answer 18

Location: uterine gland/placenta: for trans epithelial transport // enterocyte (small intestine): taking macronutrients from GI tract
Function: Increase surface area for transport
- typically found on apical side of cuboidal or columnar epithelia
- not on squamous
- core of actin filaments

Question 19

Microvilli structure

Answer 19

Core of actin filaments cross-linked by actin-bundling proteins
- stabilized by spectrin
- contractile properties: myosin II, and tropomyosin are linked to the terminal web
- villin tip

Question 20

Stereocilia

Answer 20

Location: Limited to epididymis and vas deferens (sperm movement)
- inner ear - hair cells
- thinner than microvilli
- internal actin filaments - cross linked by fimbrin
- lack villin tip

Question 21

Cilia

Answer 21

Location: nearly every cell in the body
- axoneme: microtubule-based internal structure
1) motile cilia: contain motor proteins for force production
2) primary cilia: solitary projections function as receptors
3) found only in the embryo - allow for rotational movement (gastrulation)

Question 22

Cilia Structure

Answer 22

Axoneme (Ax): microtubule core of cilia
Basal bodies (BB): microtubule organizing center, continuous with 9 outer triplets
- inner two start at transitional zone (TZ)
- alar sheets: anchors basal body to apical membrane
- basal foot (BF): thought to adjust basal bodies, rotation
- striated rootlet (SR): anchored the cilum into the cytoplasm

Question 23

Primary cilium

Answer 23

Sense fluid flow: receives mechanical, osmotic, chemical or light info and has specialized receptors

Question 24

Cell-Cell junctions

Answer 24

Occluding zone
Adhering Junctions - zonula adherens
Adhering Junctions - macula adherens

Question 25

Occluding Junctions

Answer 25

TIGHT
Location/Function: intercellular diffusion barrier forming between apical/lateral membranes
Rows of proteins
- Occludin: maintains barrier
- Claudin: backbone; aid in formation of channels
- JAM: junctional adhesion molecule

Question 26

Adhering Junctions - Zonula Adherens

Answer 26

Provide integrity for the tissue
- interact with underlying actin cytoskeleton
- E-cadherin: link two cells together - Ca2+ dependent
- intracellularly: linked to catenin, vinculin, and actin
- TEM: clear space between cells but contains E-cadherin and Ca2+

Question 27

Adhering Junctions - macula adherens

Answer 27

Desmosomes interacts with underlying intermediate filaments
- desmosomal attachment plaque: dense material anchoring desmosomal proteins to intermediate filaments

Question 28

Communicating junctions (GAP)

Answer 28

Epithelium, also cardiac muscle and nerves
- coordination of adjacent cells and activity
- formed by 12 connexon molecules
H&E stains only seen in heart

Question 29

Basal surface

Answer 29

zone between basal epithelium and the underlying connective tissue
Basal lamina: attachment site
- laminins
- collagens
- glycoproteins
Translucent using H and E stains but visible using period acid-schiff staining

Question 30

Glands are derivatives of epithelial tissue

Answer 30

Two major groups: exocrine and endocrine
Exocrine: products are secreted onto surface (ex: merocrine, apocrine, holocrine)
Endocrine: secreted into surrounding connective tissue and then bloodstream (ex: hormones)

Question 31

Unicellular glands

Answer 31

mucous secreting goblet cells of the intestines

Question 32

Multicellular glands

Answer 32

compound alveolar

Question 33

Staining glands

Answer 33

enzyme (serous) and mucous glands stain different