Epithelium

Question 1

Classification of Epithelium

Answer 1

number of layers present + cell shape at the apical surface (free, “top”)

Question 2

Number of Layers Present

Answer 2

1. Single layer = simple epithelium
2. more than one layer = stratified epithelium
   -pseudostratified
   -transitional

Question 3

Three cell shapes

Answer 3

1. squamous: cells are flat
2. cuboidal: cells are tall as they are wide
3. columnar: cells are taller than they are wide

Question 4

Simple squamous epithelium

Answer 4

-appearance: flat cells
1. endothelium - lines blood vessels & lymph vessels
2. mesothelium - lines body cavities & outer surface of many organs
-function: protection, secretion with reduces friction

Question 5

Simple cuboidal epithelium

Answer 5

-appearance: cells are cubes
-found in organs that are specialized for secretion (salivary glands and thyroid follicles)and diffusion (kidney tubules)

Question 6

Simple columnar epithelium

Answer 6

-appearance: cells are taller than they are wide
-function: secretion and absorption - lining of stomach, small intestine, large intestine
-function: secretion, transportation, protection - linking of uterus and uterine tubes

Question 7

Stratified epithelium

Answer 7

-three cell shapes at apical surface:
1. stratified squamous
2. stratified cuboidal
3. stratified columnar

Question 8

Keratinized stratified squamous (cornfield stratified squamous)

Answer 8

-Location: covering the general body surface, buccal cavity, anal region, ruminant forestomach
-appearance: multiple cell layers, surface layers are flat and covered in keratin

Question 9

Nonkeratinized stratified squamous (noncornified)

Answer 9

Location: nasal vestibule, oral, esophageal, and anal portion of digestive system, cornea eye, conjunctive, portions male/female urogenital systems

Question 10

Stratified cuboidal epithelium

Answer 10

-appearance: 2 layers of cells, apical cells are cuboidal
-location: ducts in sweat glands, mammary glands, and salivary glands

Question 11

Stratified columnar

Answer 11

-two to three layers of cells
-apical cells are columnar
-basal cells are cuboidal
-intermediate cells (if present) are polygonal

-Location: portions upper respiratory tract, ducts some glands

Question 12

Pseudostratified ciliated columnar epithelium

Answer 12

-Not stratified, cells contact basement membrane, some cells DO NOT reach the apical surface
-location: lining of upper respiratory tract, parts urogenital system, ducts of some glands
-function: secretion, absorption, lubrication, protection, transportation

Question 13

Transitional

Answer 13

-epithelium is distensible (can relax and distend)
-lines region of the urinary tact

Question 14

Mcrovilli

Answer 14

-cytoplasmic projection from apical surface of cell
-see as brush border
-function: increase surface area to increase absorption
-location: intestinal tract, proximal renal tubules

Question 15

terminal web

Answer 15

-network of actin filaments, intermediate filaments, and spectrum
-helps support cell structure

Question 16

Cilia

Answer 16

-cylindrical structure
-located on surface specialized epithelial cells, contain microtubules
-function: MOTILE
-location: pseudostratified columnar epithelium of respiratory system, part reproductive tract

Question 17

Basal body

Answer 17

-Cilia are inserted into (and held to cell) by basal bodies
-composed of microtubules in a nine triplet pin-wheel arrangements
-located: underneath cell membrane

Question 18

Stereocilia

Answer 18

-long microvilli composed of microfilaments (NOT motile)
-function: increase surface area for absorption in epididymis, signal generation in the cochlea
-location: epididymis, sensory hair of cochlea

Question 19

Glands

Answer 19

Classification: shape of the secretory unit (combo of units)
1. Simple gland: ducts do not branch
2. Compound glands: ducts branch

Question 20

Simple gland

Answer 20

1. Tubular: intestinal crypts
2. branched tubular: principal glands of stomach, endometrial glands of uterus
3. coiled tubular: sweat glands
4. acinar: urethral and periurethral glands
5. branched acinar: mucus secreting glands of cardia, sebaceous glands

Question 21

Compound glands

Answer 21

-brached ducts
1. compound tubular
2. compound acinar: exocrine pancreas
3. compound tubuloascinar: submandibular salivary gland, mammary gland, lacrimal gland

Question 22

Exocrine glands

Answer 22

-classification based on type of secretion
1. serous (parotid salivary gland) watery
2. mucous (submandibular salivary gland) thick
3. mixed (sublingual salivary gland)

Question 23

Mode of gland secretion

Answer 23

1. Holocrine: secretory cells die and become secretory product (sebaceous glands)
2. Merocrine: secretion occurs via exocytosis, secretory cells stay intact (sweat glands, exocrine pancreatic glands, salivary glands)
3. Apocrine: small part of the apex of the cell is lost with the secretory product (some sweat glands, mammary glands, prostate glands)

Question 24

Goblet cell

Answer 24

-isolated secretory glands
-arranged individually in epithelium lining (digestive/respiratory tract)
-secretioins project the tract lining

Question 25

Junctional complexes

Answer 25

1. tight junction (zonula occludens) 2. anchoring junctions -adherens junctions -desmosomes -hemidesmosomes 3. communicating junctions - gap junctions

Question 26

Tight junction (zonula occludens)

Answer 26

seals neighboring cells together in an epithelial sheet to prevent leakage of molecules between them -location: blood brain barrier, blood air barrier, bladder

Question 27

Adhering junction

Answer 27

joins an actin bundle in one cell to a similar bundle in a neighboring cell

Question 28

Desmosome

Answer 28

joins the intermediate filaments in one cell to those in a neighbor

Question 29

Gap junction

Answer 29

-a form of communication between cell members -important in cardiac muscle

Question 30

Hemidesmomes

Answer 30

-anchors intermediate filaments in a cell to the basal lamina