CHAPTER 1: TISSUES
TISSUES – cells that work/grouped
together
Function: protection, support,
communication
HISTOLOGY – deals with the study of
tissues
PATHOLOGIST – scientist specializing in
laboratory studies of cells and tissues
Principal function: to examine tissues for
any change that might indicate
disease
TYPES OF TISSUES AND THEIR ORIGIN
1. EPITHELIAL TISSUES – cover the
body surfaces, lines hallow organs
2. CONNECTIVE TISSUES – protects
and supports the body and
organs
3. MUSCLE TISSUES – generates
physical force needed to make
body structure move
4. NERVOUS TISSUES – detects
changes and respond by
generating impulses
“All of the tissues of the body develops
from the three primary germ layers ”
THREE PRIMARY GERM LAYERS
1. Ectoderm – forms epidermis
related structures, nervous
system
2. Endoderm – forms most of the
digestive system, respi., repro.,
3. Mesoderm – dermis of the skin,
lining of body cavities, mus-ske,
cardio, lymphatic system
Remember:
Epithelial tissues develop from all
the primary layers
All connective tissues and most
muscle tissues stem from
mesoderm
Nervous tissues develops from
ectoderm
CELL JUNCTIONS
- tightly join most epithelial, some
muscle, and nerve cell together
- THE CONTACT POINT between
plasma membranes of tissue cells
5 TYPES OF CELL JUNCTIONS
1. TIGHT JUNCTIONS
- connect the “cell tissues” that line
the surface organs of body cavities
- Seal off passageways; prevents
the content of organs from leaking
Examples: Cells of epithelial tissues in
the stomach and intestines
2. ADHERENS JUNCTIONS
- Made of plaque, dense layer of
CHON
- attaches to membrane proteins and
microfilaments of cytoskeleton
Plaques
-Resist separation of cells
Cadherins/ transmembrane
glycoproteins
- Inserted into plaque and join cells
ADHESION BELTS – extensive
bonds formed by epithelial cells
3. DESMOSOMES
-Composed of plaque and linked by
cadherins(transmembrane
glycoproteins)
- Help attach adjacent cells to each
other
4. HEMIDESMOSOMES
-resemble desmosomes
-does not attach adjacent cells
-hemidesmosome = half
desmosomes
