ANIMAL TISSUES
ANIMAL TISSUES
Cells are not usually isolated -- instead they're
surrounded by other similar cells: TISSUE.
What are tissues??
DEF: Group of similar cells & intercellular substance
functioning together to perform a specialized activity.
Study of tissues: HISTOLOGY
Histio = “tissue”
Logos = “study of”
All animal tissue can be place in 1 of 4 types.
What are the 4 types??
1) epithelial
2) connective
3) muscle
4) nervous
EPITHELIAL TISSUE
2 locations: a) glands
b) covering surfaces
lining “lumens”
Organized in continuous layers ..... thin to thick.
Tightly packed .... little intercellular material.
Avascular --- not penetrated by blood vessels.
Nonneural
All epithelial are anchored by a basement membrane.
Rules for Naming Epithelia are based on…
Number of cell layers
Simple (1 layer)
Stratified (2 or more layers)
Cell shape
Squamous
Cuboidal
Columnar
Simple squamous epithelium
Simple columnar epithelium
Stratified squamous epithelium
Some epithelia are simple squamous … others are
heavily stratified.
Why does this make sense?
Examples??
Simple Squamous
Epithelia
SMALL INTESTINE LINING
CONNECTIVE TISSUE
Most abundant tissue in body.
- Binds (ligaments)
- Supports (mesenteries)
- Protects (bone)
Does not occur on free surfaces (like epithelia).
Cells are few ..... fibroblast is a common example.
“Matrix” is abundant.
Matrix is produced by the CT cells --- nonliving.
May be fluid, semifluid, mucus-like, or fibrous.
Matrix determines the CT’s quality:
- cartilage matrix = firm but pliable
- bone matrix = hard & not pliable
Matrix often contains protein fibers ... most abundant is
collagen.
Collagen is produced by fibroblasts.
Collagen represents 30 % of total body protein!!
Completely inelastic ... greater tensile strength
than steel.
Another common protein fiber: elastic fiber
Loose (= areolar) Connective Tissue
Adipose Tissue
Dense Regular Connective Tissue
Dense Irregular Connective Tissue
Hyaline Cartilage
Bone Tissue
Compact Bone Tissue
Blood (a connective tissue!)
MUSCLE TISSUE
3 types – 3 locations
- Skeletal muscle
- Cardiac muscle
- Smooth muscle
Skeletal (voluntary & striated) muscle
Cardiac muscle
(striated & involuntary)
Smooth muscle
NERVOUS TISSUE
2 Main Cell Types
- Neurons
- Glial cells