Epithelial Tissue

Question 1

Body parts and relationship hierarchy

Answer 1

1. chemical
2. cellular
3. tissue
4. organ
5. system

Question 2

Histology Definition

Answer 2

Study of microscopic structures of tissues

Question 3

Types of Tissues

Answer 3

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

Question 4

Nervous Tissue

Answer 4

Brain, Spinal Cord, Nerves

Question 5

Epithelial Tissue

Answer 5

Lining of GI tract organs & hollow organs
Skin surface

Question 6

Muscle Tissue

Answer 6

Cardiac Muscle
Smooth Muscle
Skeletal Muscle

Question 7

Connective Tissue

Answer 7

Fat
Bone
Tendon

Question 8

H&E Stains

Answer 8

Hematoxylin – behaves like a base & stains blue

Eosin – behaves like an acid & stains pink

Question 9

Parenchyma

Answer 9

cells responsible for the organ’s specialized function

Question 10

Stroma

Answer 10

supporting cells, usually connective tissue

Question 11

Epithelial Tissue

Answer 11

composed of sheets of cells that cover body surfaces, line body cavities, & form glands

Question 12

Epithelia Function

Answer 12

physical protection

controls permeability - filtration, absorption, excretion

provides sensation

produces secretions

Question 13

Epithelia Characteristics

Answer 13

• densely packed cells bound by specialized cell junctions
• polarity
• attachment via basement membrane to underlying CT
• avascular
• innervated
• regenerates

Question 14

Basement Membrane

Function

Answer 14

acellular, consists of molecules secreted by basal epithelial cells & cells of CT

1. supports overlying epithelium
2. anchors epithelial tissue to underlying CT
3. semipermeable
4. scaffold for repair and regeneration

Question 15

Microvilli

Answer 15

finger like extensions on apical surface

abundant on epithelial surface where absorption & secretion occur

function - increase absorptive surface area

Question 16

Cilia

Answer 16

long, motile processes on apical surface; microtubules & associated proteins form their core

respiratory tract, uterine tube

function - beat in a coordinated fashion to move substances over the epithelial surface

Question 17

Tight (Occluding) Junctions
zonula occludens

Answer 17

binds plasma membrane of adjacent cells together

seal created by tight interactions between transmembrane proteins: claudin & occludin

fn - acts as a permeability barrier, prevents passive flow between cells, limits movement of membrane proteins from surfaces

Question 18

Anchoring Junctions

Answer 18

attach cytoskeletons of adjacent epithelial cells together

1. adherens junction
2. desmosomes
3. hemidesmosomes

Question 19

Adherens Junction
zonula adherens

Answer 19

actin microfilament of adjacent cells are linked by transmembrane proteins: cadherins

fn - firmly anchors neighboring cells & provides stength & distributes shear forces

band - goes all around

Question 20

Desmosomes
macula adherens

Answer 20

disc shaped

links intermediate filaments of adjacent cells by transmembrane proteins: cadherins

fn - creates strong connections between cells & distriubutes shear forces

Question 21

Hemidesmosomes

Answer 21

links intermediate filament network of the cytoskeleton across the basal surface to the BM by transmembrane proteins: integrins

fn - resist separation from underlying tissue

Question 22

Gap Junctions

Answer 22

Complex of 6 transmembrane proteins (connexins) form channels (connexons)

multiple connexons from 2 adjacent cells align to form the gap junction

fn - mediates intercellular communication

Question 23

Simple Squamous

Answer 23

lines vessels & serous lining of cavities

fn - regulate passage of substances into underlying tissue

Question 24

Simple Cuboidal

Answer 24

surface of ovary, kidney tubules, some glands

fn - line surfaces involved in secretion & absorption

Question 25

Simple Columnar

Answer 25

lines small intestine, colon, stomach, gall bladder, uterine tube fn - secretion & absorption; larger cells thus more organelles than cuboidal

Question 26

Pseudostratified Columnar

Answer 26

appears stratified but all cells are anchored to BM & nuclei appear at different levels usually has cilia lines respiratory tract, ductus deferens, & epididymis fn - secretion & conduit

Question 27

Stratified Squamous Keratinized Epithelium

Answer 27

develops a tough layer of keratin (no nuclei) & found in skin fn - protection against abrasion, water loss, UV, foreign particles

Question 28

Stratified Squamous Non - Keratinized Epithelium

Answer 28

lines wet surfaces - mouth, esophagus, pharynx, vagina fn - protection against abrasion, water loss, UV, foreign particles

Question 29

Transitional

Answer 29

stratified epithelium lines bladder, ureters, urethra; surfaces that change in response to stretching & relaxing in relaxed state looks like stratified cuboidal, except apical cells are found and large fn - allows for stretch and recoil

Question 30

Glandular Epithelia

Answer 30

exocrine glands: secretions travel through ducts to the epithelial surface endocrine glands: ductless glands that exist within some covering epithelia

Question 31

Exocrine Glands

Answer 31

serous glands: watery fluid with enzymes mucous glands: secrete glycoproteins called mucins mixed exocrine glands: contains both serous and mucus secretions

Question 32

Unicellular Glands goblet cells

Answer 32

secrete mucus onto exposed surface of epithelial sheet & functions to protect apical surface

Question 33

Structural Classification of Exocrine Glands

Answer 33

Duct: simple - unbranched compound - branched Secretory portion: tubular or branched tubular acinar or alveolar

Question 34

Modes of Secretion - Exocrine

Answer 34

merocrine glands - secretions released by exocytosis holocrine glands - entire vesicle shed into lumen apocrine glands - pinched off portion of cell is secreted

Question 35

Endocrine Glands

Answer 35

ductless gland that exist within some covering epithelia secrete cell product (hormones) directly into intersititial fluids or blood hormones enter systemic circulation by diffusion