Basic Tissue Types: Epithelium

Question 1

Endothelium

Answer 1

lining of the blood or lymphatic vessels

Question 2

mesothelium

Answer 2

lining of serous body cavities

Question 3

main functions of epithelia

Answer 3

absorption, protections, secretion

Question 4

single layer of epithelium that provides all 3 functions

Answer 4

small intestine

Question 5

basement membrane

Answer 5

support for epithelial tissue
separate epithelia from support tissue beneath
Never penetrated by blood vessels

Question 6

external laminae

Answer 6

structure for muscle and nervous tissue similar to that of the basement membrane for epithelial tissue

Question 7

basal surface

Answer 7

side of epi facing the basement membrane

Question 8

apical surface

Answer 8

side of epi which faces outwards (away from basement membrane)

Question 9

3 types of junctions

Answer 9

anchoring
occluding
communication

Question 10

anchoring junction

Answer 10

provides mechanical strength

Question 11

occluding junction

Answer 11

link cells to form an impermeable barrier

Question 12

communication junction

Answer 12

allow direct communication between cells

Question 13

Classification of epis is based on

Answer 13

number of layers
cell shape
presence of surface specializations

Question 14

layers of cells

Answer 14

simple: 1 layer
stratified: at least 2 layers
pseudostratified: only 1 layer thick, but gives appearance of being stratified

Question 15

cell shapes

Answer 15

squamous: flattened
Cuboidal: cube shaped
columnar: hight is at least 2x the width

Question 16

examples of surface specializations

Answer 16

they are features on cell surface that enhance function of the epi
keratin found on skin surface (increases protective nature of the skin surface)
cilia, microvilli, stereocilia

Question 17

Simple epi

Answer 17

1 layer of cells
absorption, secretion, selective diffusion
little protection against abrasion

Question 18

Simple squamous epi

Answer 18

Appearance: flattened, irregularly-shaped cells, “fried egg”

Location: Lungs, walls of blood capillaries, lining of pleura, pericardial and peritoneal cavities

Function: Passive transport of gases and fluids

Question 19

simple cuboidal epi

Answer 19

Appearance: square or cube shaped, section perpendicular to basement membrane
Location: lining of small ducts or tubules, collecting ducts of kidneys, salivary glands, pancreas
Function: excretory, secretory and absorptive

Question 20

Simple columnar epi

Answer 20

Appearance: cells are tall (“columns”) from the basement membrane; height may vary depending on site/function
Location: mucosal lining or small intestine, stomach, gall bladder
Function: absorption, secretion

Question 21

simple columnar ciliated epi

Answer 21

columnar cells with cilia
cilia propel a fluid or minute particle over the surface by beating in synchonic rhythm with adjacent cells
Ex. egg moving through fallopian tube

Question 22

pseudostratified columnar ciliated epi

Answer 22

Appearance: appear to have more than one layer of cells but all cells are touching the basement membrane (actually only one layer); nuclei at different levels; cilia on apical surface
Location: large airways of respiratory system

Function: cilia collect material; propel a fluid or minute particle

Question 23

Stratified epi

Answer 23

more than one layer of cells
primarily protective functions
degree of stratification depends on amount of physical stress the surface must endure

Question 24

Stratified squamous epi

Answer 24

Appearance: multiple layers of cells (transition from cuboidal basal layer to flattened outer layer)
Location: Oral cavity, pharynx, vagina, areas with minimal abrasion that are kept moist by glandular secretion
Function: Protection

Question 25

stratified squamous keratinizing epi

Answer 25

epi undergoes process of keratinization
results in tough, non-cellular surface layer consisting of protein, keratin and remnants of degenerated epi cells
Ex. skin

Question 26

stratified cuboidal epi

Answer 26

Appearance: 2-3 layers of cuboidal cells
Location: lining of larger excretory ducts (salivary glands, pancreas, sweat glands)
Function: provides more robust lining than simple epithelium

Question 27

stratified columnar epi

Answer 27

rare
2 layers of columnar cells
found in ocular conjunctiva, largest ducts of salivary glands, urethra

Question 28

transitional epi

Answer 28

accommodates stretching and withstands toxicity of urine
confined to urinary tract
nondistended: appears 4-5layers
stretched: appears 2-3 layers

Question 29

what layer are epis classified from

Answer 29

the apical layer (outermost)