Ex 1 Epithelial Tissues

Question 1

Types of epithelial tissue based off of number of layers and shape

Answer 1

Layers: simple or stratified
Shape: squamous, cuboidal, or columnar

Question 2

Characteristics of epithelial tissue

Answer 2

• cells typically have a relatively uniform geometric shape
• cells are tightly bound
• have relatively little intercellular matrix
• typically display free surface
• cells exhibit polarity
• do not contain blood vessels
• sit on top of basement membrane

Question 3

Free surface

Answer 3

exposed to external environment (lumen)

Epithelioid tissue lacks free surface

Question 4

How do the cells exhibit polarity?

Answer 4

Apical domains- surface in contact with lumen/external environment
Basolateral domains- surfaces that are locked together by special junctional complexes with neighboring cells and cells in contact with basal lamina

Question 5

How can epithelial cells live without having blood vessels?

Answer 5

They are close enough to blood vessels in connective tissue that they collect O2 and blood via diffusion

Question 6

What derives from ectoderm, endoderm, mesoderm?

Answer 6

Ectoderm- skin epidermis and glands
Endoderm- lining of the GI tract (including glands)
Mesoderm- the lining of blood vessels, mesothelium (layers that cover organs and line body cavities), Bowman’s capsule

Question 7

Two components of basement membrane

Answer 7

Basal lamina and reticular lamina

Question 8

Basal lamina

Answer 8

• next to epithelial layer
• composed of type IV collagen + glycoproteins, PAS+
• absent in lymph vessels & hepatic sinusoids because they are designed to be leaky

Question 9

Reticular lamina

Answer 9

• next to underlying connective tissue

- consists of argyrophlic fibers, reticular fibers, glycoproteins

Question 10

Functions of basement membrane

Answer 10

• selective filterration barrier
• scaffold for embryogenesis and regeneration (due to wounds)
• stabilization of tissue shapes

Question 11

Surface modifications of epithelium

Answer 11

cilia, stereo cilia, microvilli (brush border)

Question 12

Examples of lightly/heavily keratinized epithelial tissue

Answer 12

lightly- esophagus and vagina, retain nuclei

heavily- epidermis, nuclei are absent

Question 13

Pseudostratified

Answer 13

• always simple columnar
• cells are in contact with basal lamina
• appearance of stratification is due to the variable positions of the nuclei within the cells
• epididymis and trachea

Question 14

Transitional

Answer 14

• all cells in contact with basal lamina
• dome-shaped surface cells give appearance of stratified
• urothelium- urinary tract

Question 15

Basolateral surface modifications

Answer 15

• epithelial tissues often function to maintain concentration differences
• some form tight while others form leaky barrier (determined by molecular complexes that hold them together)
• epithelial cell are held tight to non-cellular basal lamina (basal membrane) that helps to anchor and stabilize the epithelial layer

Question 16

Simple squamous epithelium

Answer 16

• lines lumina of ducts, vessels, and other tubular structures
• forms walls of alveoli, Bowman’s capsules and inner surfaces of membranous labyrinth and tympanic membrane

Question 17

Simple cuboidal epithelium

Answer 17

• low or high (approaching squamous or columnar)
• may have brush border (kidney tubules) on apical surface
• found on surface of ovary, pigmented epithelium of retina, kidney tubules, glands and ducts, terminal bronchioles, choroid plexus and anterior capsule of lens of eye

Question 18

Simple columnar epithelium

Answer 18

• may have striated border (intestinal cells) on apical surface composed of microvilli
• ciliated is found in the URT, uterine tubes, uterus, paranasal sinuses, and the central canal of the spinal cord
• non-ciliated found in digestive tract beginning with the cardia of the stomach, gall bladder, and in parts of excretory ducts of glands

Question 19

Stratified squamous epithelium

Answer 19

• heavily keratinized: epidermis with connective tissue papillae, cornea without connective tissue papillae
• lightly/non-keratinized in esophagus, vagina, lining of mouth, tongue, part of of epiglottis

Question 20

Stratified cuboidal epithelium

Answer 20

seldom found but may occur in small areas of the anal mucosa, large excretory duct of some glands, part of male urethra

Question 21

Stratified columnar epithelium

Answer 21

seldom found, occurs in the ducts of adult sweat glands, fornix of the conjunctiva of the eye, parts of the male reproductive/urinary tract, pharynx and epiglottis

Question 22

Pseudostratified epithelium

Answer 22

• ciliated is found in trachea

- with stereo cilia is found in the epididymis

Question 23

Transitional epithelium

Answer 23

urothelium

Question 24

Functions of epithelial tissues

Answer 24

• covering and lining

- glandular

Question 25

Function in protection (covering and lining)

Answer 25

especially stratified squamous

Question 26

Function to maintain concentration differences (covering and lining)

Answer 26

tight vs leaky barriers (lining of gall bladder, PCT)

Question 27

Glandular function

Answer 27

• height reflects level of secretory or absorptive activity (high columnar secretes more and will shrink down when inactive)
• simple columnar functions primarily in secretion of enzymes and mucous and absorption of nutrients and fluids

Question 28

CQ: Simple, non-ciliated columnar epithelium is most likely to be found associated with which of the following?

Answer 28

Digestive (microvilli)

Question 29

CQ: Junctional complexes are associated with which cellular domains?

Answer 29

Basolateral

Question 30

CQ: Transitional epithelium is associated with which of the following systems?

Answer 30

Urinary (urothelium)

Question 31

CQ: Although not common, stratified cuboidal epithelium may be found in which of the following areas?

Answer 31

Part of the male urethra

Question 32

CQ: Lightly keratinized stratified squamous epithelium is characteristic of which of the following locations?

Answer 32

Vagina