TISSUES
I. CLASSIFICATION OF TISSUES
-- Histology: microscopic study of
tissues
-- Tissue: group of similar cells that
perform a common function
-- 4 kinds:
1) Epithelium
*
covers body/organ surfaces
*
lines body cavities
*
forms glands
2) Connective
*
binds/supports/protects other tissues
and organs
3) Muscle
*
moves body, materials within body
4) Nervous
* makes up the nervous system
Epithelia
II. CHARACTERISTICS OF EPITHELIA (fig 4.1)
– cellularity
--
polarity
* apical surface
* basal surface
--
bound to underlying tissue by a basement membrane
--
avascularity
– high regenerative capacity
--
Classified by LAYERS (fig 4.2):
1)
Simple Epithelium - one layer thick
2)
Stratified Ep. - many layers thick
* protective function
--
Classified by cell SHAPE:
1)
Squamous - flattened cells
2)
Cuboidal – about as tall as they are wide
3)
Columnar – taller than wider shaped cells
III. SIMPLE EPITHELIA
(Table 4.3)
A. Simple Squamous Epithelium
* one layer of flattened cells
B. Simple Cuboidal
Epithelium
*
single layer of cube-shaped cells
C. Simple Columnar Epithelium
*
single layer of tall cells
*
microvilli and a brush border
*
goblet cells
D. Pseudostratified
Columnar Epithelium (table 4.5)
*
cells are columnar, irregularly shaped
*
all cells are attached to basement membrane
*
some kinds have cilia (pseudostratified
CILIATED columnar epithelium)
*
goblet cells
IV. KINDS OF STRATIFIED EPITHELIA
A. Stratified Squamous
Epithelium (tbl 4.4)
*
upper layers of cells are flattened, lower layers appear cuboidal
*
two kinds:
1)
keratinized
**
contains keratin
**
most superficial layers consist of dead cells
2)
nonkeratinized
**
most superficial cells are alive and kept moist
B. Transitional Epithelium (tbl 4.5)
*
found in most of the urinary tract
*
some cells are binucleated
*
withstands distention (stretching) and relaxing of bladder
V. GLANDS (figs 4.5-4.6)
Exocrine
Glands formed from epithelial tissues- they secrete their
materials onto a free surface
A. Unicellular
*
one cell
*
ex: goblet cell
*
secrete mucus
B. Multicellular
*
secrete materials through a duct
1)
merocrine glands
**
secretion passes from cell
**
cell remains intact
2)
apocrine glands
**top part of the cell is pinched off, becomes the secretion
3) holocrine glands
** cells rupture, die, and become the secretion
Connective
Tissue
VI. CHARACTERISTICS OF
C.T. (fig 4.7, 4.8)
– derived from mesenchyme
(embryonic CT)
--
consists of:
1)
Cells
2) Fibers (protein)
3)
Ground Substance
-- CT typically is vascular
VII. CLASSIFICATION OF
C.T.
A.
Connective Tissue Proper
1) Loose CT (table 4.9)