4 Types of Tissues
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Epithelial
 Covers body surfaces and lines hollow organs,
body cavities, duct, and forms glands
Connective
 Protects, supports, and binds organs.
 Stores energy as fat, provides immunity
Muscular
 Generates the physical force needed to make body
structures move and generate body heat
Nervous
 Detect changes in body and responds by
generating nerve impulses
Development of Tissues

Tissues of the body develop
from three primary germ
layers:
 Ectoderm, Endoderm,
and Mesoderm
 Epithelial tissues develop
from all three germ layers
 All connective tissue and
most muscle tissues drive
from mesoderm
 Nervous tissue develops
from ectoderm
 Internal organs develop
from endoderm
Tight Junctions

Web-like strands of
transmembrane proteins
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Fuse cells together
Seal off passageways
between adjacent cells
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Common in epithelial
tissues of the stomach,
intestines, and urinary
bladder
Help to retard the passage
of substances between
cells and leaking into the
blood or surrounding
tissues
Desmosomes

Contain plaque and
cadherins that extends into
the intercellular space to
attach adjacent cells
together
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Desmosome plaque
attaches to intermediate
filaments that contain
protein keratin
Prevent epidermal cells
from separating under
tension and cardiac
muscles cells from pulling
apart during contraction
Gap Junctions

Connect neighboring cells
via tiny fluid-filled tunnels
called connexons
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Contain membrane proteins
called connexins
Plasma membranes of gap
junctions are separated by
a very narrow intercellular
gap (space)


Communication of cells
within a tissue
Ions, nutrients, waste,
chemical and electrical
signals travel through the
connexons from one cell to
another
Epithelial Tissues

Epithelial tissue consists of
cells arranged in continuous
sheets, in either single or
multiple layers

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Closely packed and held
tightly together
Covering and lining of the
body
Free surface
3 major functions:

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
Selective barrier that
regulates the movement of
materials in and out of the
body
Secretory surfaces that
release products onto the
free surface
Protective surfaces against
the environment
Connective Tissue
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Most abundant and
widely distributed tissues
in the body
Numerous functions

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Binds tissues together
(tendons/ligaments)
Supports and strengthen
tissue (bone)
Protects and insulates
internal organs (fat)
Compartmentalize and
transport (blood)
Energy reserves and
immune responses
Connective Tissue Extracellular Matrix

Ground substance

Between cells and fibers

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Fluid, semifluid, gelatinous, or calcified
Functions to support and bind cells, store water, and allow
exchange between blood and cells
Complex combination of proteins and polysaccharides
Fibers
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Collagen fibers
Elastic fibers
Reticular fibers
Muscular Tissue

Consists of elongated
cells called muscle
fibers or myocytes
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Cells use ATP to
generate force
Functions in
movement, generating
heat, digestion
Classified into 3 types:
skeletal, cardiac, and
smooth muscular
tissue
Skeletal Muscle Tissue
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Attached to bones of the skeleton
Have striations
Voluntary movement or contractions by conscious control
Vary in length (up to 40 cm) and are roughly cylindrical in
shape
Muscular Tissue

Cardiac muscle tissue
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Have striations
Involuntary movement or contraction is not consciously
controlled
Intercalated disc unique to cardiac muscle tissue

Walls of hollow internal structures
Smooth
Tissue
Blood Muscle
vessels, airways
of lungs, stomach, and intestines
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Nonstriated
Usually involuntary control
Nervous Tissue

Consists of two principle types of cells
 Neurons or nerve cells
 Neuroglia
Cellular
Movement
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Microtubules cilia & flagella
Microfilamentsamoeboid
movement & muscle cells
Vertebrate skeletal muscle
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The action of
muscle is to
always contract
Muscles are
attached in
antagonistic pairs
The basic functional unit of muscle
Skeletal muscles: striated & multinucleate
I=thin
H=thick
A=thick + thin
A
A
)Myofilaments
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