Chapter 2 Epithelium. 1.General feature: 1) contain more cells and less extracellular ground substance 2) Polarisaton : --- free surface: face air or other things --- basal surface: have basement membrane, to face underlying connective tissue (CT)
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1) contain more cells and less extracellular ground substance
---free surface: face air or other things
---basal surface: have basement membrane, to
face underlying connective tissue (CT)
3) Avascularity, but innervation:
---no blood vessels
---rich in nerve terminals
4) Having functions of
and sensory reception
2.Classification of Epithelium
1)Covering epithelium: the epithelium which cover body surface or line the inner surface of body cavities, tubes and sac.
2)Glandular epithelium: the epithelium which main function is secretion.
3)Sensory epithelium: the epithelium which has special sensory function.
3. Classification of covering epithelium:
According to the number of layer and shape of cells
Simple epi.: ---simple squamous epi.
---simple cuboidal epi.
---simple columnar epi.
---pseudostratified ciliated columnar epi.
Stratified epi.:---stratified squamous epi.
---stratified columnar epi.
one layer flattened cells, cell border are interdigitate
with flattened ellipsoid nucleus
---function: a) transport of materials
b) facilitates movement of viscera
2)simple cuboidal epi.:
---distribution: /the renal tubule
/the some ducts of glands
---function: covering and secretion
3)simple columnar epi.:
---distribution: gastrointestinal tract
---function: secretion and absorption
goblet cell: scattered, secreting granules-mucinogen granules-mucus
simple columnar epi
four types of cells
4)pseudostratified ciliated columnar epi.:
1, Four types of cells
columnar cell (ciliated); goblet cell
fusiform cell; basal cell: pyramid-shaped
2, Every cell locate on basement membrance: Simple epi.
---distribution: inner surface of large duct of respiratory
The epithelium of trachea
5)stratified squamous epi.:
in the distendedbladder
---defination: delicate finger-liked projections of cell-membrane and cytoplasm protruding from the free surface
0.1um in diameter, with different longth.
surface: cell membrane with cell coat
core: longitudinal microfilament-actin filament fixed on terminal web
terminal web: made up of transverse-arranged filament at the apical side of cells
---function: increase the surface areas
---distribution: striated border: intestinal epi. cell
brush border, e.g. proximal renal tubule
---defination: a thick layer of extracellular glycoprotein
---function: adherence, supporting, protection, exchange of material and recognize
---defination: elongated, mobile projections of cell membrane and cytoplasm protruding from free surface
---function: swing to produce a forward-moving wave
---distribution: epithelial cells of respiratory tract
---intercellular connection of adjacent cells:
①Tight junction (zonula occludens):
---function: seal the space between cells
② intermediate junction (zonula adherens):
keep the cell shape
transfer cell contract force
③desmosome (macula adherens):
with attached tonofilament-intermediate filament (karatin)
---function: firmly connection
④gap junction (communicating junction):
-consist of protein
-7~9nm in diameter
-composed of 6-subunits of proteins- connexin
-2nm channel: hydrophilic channel
---function: provide a pathway between cells
junctional complex: four types of junctional structures (at least two types) get together.
---defination: a sheet of membrane-liked amorphous material interposed between epi. cells and underlying CT.
--basal lamina: 20-300 nm, electron-dense, thread-liked and amorphous ground substance, produced by epi. cell
--reticular lamina: reticular tissue + ground substance, produced by CT
② plasma membrane infolding
(basal longitudinal striation):
---defination: the infolding of cell-membrane with many mitochondria at the basal surface of epi. cell
---distribution: mainly in proximal renal tubule and distal renal tubule.
---is half of desmosome.
5. Glandular epi. and gland
exocrine gland: discharge the secretion through a duct system
endocrine gland: release the secretion directly into blood steam
2) structure of exocrine gland:
①acinus (secreting unit):
according the nature
serous secretory cells
---function: produce a serous secretion
b.mucous acinus: mucous secreting cells
---function: secretes mucus
c.mixed acinus: two types of cells
---from simple squamous epi to simple columnar or stratified epi.
---carry out the secretions
---secrete or absorb water and ions
2. An endocrine gland passes its secretion directly into the
3. The nucleus is flattened against the basal plasma memberane of the cells, the cytoplasm is filled with large mucigen droplets, it is the
In H.E. stain sections, the cytoplasm is stained pink by ___________, the nucleus is stained purple-blue by___________________________.
The procedure of preparation of histologic slides includes mainly______________________, ___________,_________________,
_____________, ______________,and sectioning.
Obtaining the specimen
The 4 basic types of tissue are ______________,_________________,_________________ and _________________.
Epithelia are mainly classified into 2 groups: ______________and_______________.
The intercellular junctions of epithelial cells are (1) _______________,
(3) _____________, and (4)______________. When 2 or more kinds of them are present together, we called it __________________.
7. Specialized structures on basal surface of epithelial cells are ________________________________,_____________________________ and ______________________.
plasma membrane infolding
8. Pseudostratified columnar ciliated epithelium consists of 4 kinds of cells with different shape and height, but all set on the basal membrane: ________________________,
columnar cell (ciliated)