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Chapter 4
TISSUES
Epithelium Tissue
I. Tissue
A. When organisms advanced and became
more complex in structure there came a
need for specialized parts to meet the
demands of the larger body size.
 These demands are met by groups of
specialists – cells, which do only one
job and this one job well. This is called
division of labor.
I. Tissue Continued
Certain groups (cells, tissues, and
organs) have divided up the work
which must be done to continue life by
being specialized.



The cells (which are basic units of
structure) become adapted and changed
(differentiated) for their specific function.
They are grouped together to work with
greater efficiency and are known as
tissues.
I. Tissue Continued
B. Cells that are similar in structure and
function form tissues. Cell structure is
directly related to cell function.
Tissues that work together toward a
common function form an organ.
Organs that work together to perform
a major function composes an organ
system.
I. Tissue Continued
C. Tissues – there are 4 basic types of
tissues in the human body.
 Study of histology
1. Epithelium
2. Muscle
3. Nerve
4. Connective (ct)
I. Tissue Continued
D. Types of Tissues:
1.
Epithelium
a) Location: 2 types of epithelium:
1. covering the surfaces of the
body, internal and external
2. glandular epithelium (glands)
I. Tissue Continued
Characteristics
1. Always one free surface
2. Rest on a basement membrane
3. Has cells close together
4. Little matrix (if any) between
cells
b)
Free surface
Basement membrane
Junk tissue
I. Tissue Continued
c)
Functions
1. Protection; against dehydration,
bacterial invasion, chemicals, harmful
rays, and cuts and abrasions
2. Secretions; all glands (exocrine)
3. Absorption; stomach, small intestine,
large intestine
4. Lubrication; movement (secretionsknee capsule)(cilia- fallopian tubes,
lungs)
5. Expansion; bladder
I. Tissue Continued
d)
Classification by arrangement and
shape
• Always have 2 names:
Number of cell layers or
arrangement.
2) Shape
1)
I. Tissue Continued
1.
Arrangement (#cell layers)
a.Simple- one cell thick
b.Stratified – more than one cell
layer thick
c.Pseudostratified – all cells touch
basement membrane but not all
cells reach the top.
I. Tissue Continued
Shape
a.Squamous (skw a’mus)flat/scale like and irregular
b.Cuboidal- cube or boxlike
c.Columnar (ko-lum’nar)tall/column
2.
I. Tissue Continued
The shape of the nucleolus
conforms to that of the cell.
Three main types.
1. Disc
2. Spherical
3. elongated
e.
e)Examples specific types of epithelium tissue
Simple epithelium
a) Simple squamous- endothelium
(lining of blood vessels)
1. Location; arteries, veins, and
capillaries
2. Function; protection, allows
for passage of materials by
diffusion; filtration; secretes
lubricating substances
1.
This shows single layers
of squamous (flat) cells
around the air spaces
(alveoli) of the lung.
e)Examples specific types of epithelium tissue
Continued…..
b)Simple cuboidal
1.Location; ducts of
glands
2.Functions; secretion
and absorption
I. Tissue Continued
c)Simple columnar
1.Location; digestive tract
and some ducts
2.Function; secretion of
mucus, enzymes and
absorptive
I. Tissue Continued
d)Ciliated simple
columnar
1.Location; lungs,
fallopian tubes, trachea
2.Function; movement
and protections
I. Tissue Continued
2. Stratified
Epithelium
a)Stratified squamous
1.Location; ectoderm (skin),
mouth, esophagus
2.Function; protection
I. Tissue Continued
b)Transitional
1.Location; bladder
2.Function; expansion
I. Tissue Continued
Pseudostratified Epithelium
a)Pseudostratified columnar
(ciliated)
1.Location; trachea,
fallopian tubes
2.Function; protection and
movement
3)
Muscle Tissue
2. Muscle Tissues
a. This tissue is one on which the
body depends for movement.
Some movement may be so small
that it can only be seen by the aid
of a microscope. This movement is
possible by the muscle cells
ability to contract.
2. Muscle Tissues Continued
Muscle tissue is classified by
the type of cells that form the
tissue.
There are 3 classes;
1. Smooth- unstriated, visceral
2. Striated- skeletal
3. Cardiac- heart
b.
2. Muscle Tissues Continued
Smooth muscle
1. Most primitive type of muscle
2. The cell is the unit of
function & structure
c.
2. Muscle Tissues Continued
3.
Structure
a)Generally spindle shaped
b)1 nucleus/cell
c)Contains no striations; however
does have filaments
i. Microfibrils that are responsible
for contraction, they are just
not organized into striations.
2. Muscle Tissues Continued
d) Gap junctions; not all cells are
innervated by a nerve. There are
gap junctions between cells
which pass the impulse of the
contraction to the other cells- in
a slow progressive wave-like
contraction.
2. Muscle Tissues Continued
Location
a.Found around walls of blood
vessels
b.In the digestive tract
c.Uterus, and
d.Hair follicles
4.
2. Muscle Tissues Continued
Function
a)Involuntary
b)Slow, sustained
contractions,
c)Does not tire easily and
d)Function in wave-like
contractions
5.
2. Muscle Tissues Continued
Striated/Skeletal muscle
1. These “cells” are usually large and
contain more than 1 nucleus.
Current theory sites the possible
fusion of many primitive muscle
cells in the embryo to produce
these “cells”, for that reason the
term muscle fiber is used to refer
to the muscle cell.
d.
2. Muscle Tissues Continued
Myofibrils are the unit of
contraction and sarcomeres
the unit of function
3. Location
a)Skeletal location
2.
2. Muscle Tissues Continued
4.
Function
a)Voluntary muscle
b)Rapid, strong contractions
c)Fire easily
d)Antagonistic arrangementmuscles are arranged so they
work opposite each other
2. Muscle Tissues Continued
5.
Structure
a.These appear as unbranching
bundles of elongated cells
b.Multi-nucleated peripheral (on
the outer edges) nuclei
c.Composed of myofibrils, small
units that contain the protein
filaments responsible for
contraction
2. Muscle Tissues Continued
d.
Light and dark bands called
striations are visible
i. Striations are caused by
filaments of protein in the
myofibril
ii. There are two major proteins
involved, myosin (thick) and
actin (thin).
2. Muscle Tissues Continued
iii.The
light and dark bands are
caused by the overlapping of
these filaments.
iv. The plasma membrane is called
the sarcolemma instead of the
plasma membrane.
v. The cytoplasm is referred to as
sarcoplasm.
Sacro= muscle
Lemma= covering
Structure of Striations
Sacromere
Myosin
Dark Band
Actin
Light
Band
Myosin
Z- Line
Actin
Myosin
Structure of Striations
Sarcomere
Dark Band
Z line
Dark Band
Actin
Myosin
Light Band
Light Band
2. Muscle Tissues Continued
e.
Cardiac
1. Function
a.Involuntary muscle
b.Rapid
c.Rhythmic
d.“strongest” muscle; does not
tire easily
2. Muscle Tissues Continued
Location
a.Heart muscle
2.
2. Muscle Tissues Continued
Structure: Highly branched with cells
connected by overlapping projections
of the sacrolemma called intercalated
discs. Also autorhythmic- generating
its own action potential.
a.Much like a striated muscle
b.Composed of myofibrils, which are
in turn composed of protein
filaments
c.Striated
d.1 or 2 nuclei in each cell
2. Muscle Tissues Continued
e.Nuclei are found in the
center of cells
f. Cells are joined and
branched to form a network
for strength.
i. Strength /intercalated
discs are found running
across fibers
2. Muscle Tissues Continued
a)Gap junctions- these help carry
impulses to adjoining cells and
transfer the contraction. Impulses
(synchronized) are carried by
modified cardiac muscle fibers, not
nerve fibers.
Connective Tissue
C.T.
3.
Connective Tissue
A. Functions
1. Connections;
a) Cell to cell
b) Organs to organs
c) Bone to muscle
d) Bone to bone
2. Pads organs
C.T. Continued
Heals wounds
6. Defense mechanisms
7. Energy storage
8. Passage way
b. Location- found throughout the
body
5.
C.T. Continued
c.
Characteristics
1. Most widely distributed tissue
2. Few cells
3. Considerable matrix
4. Very indistinct plasma
membrane
5. Highly vascular – many fibers
6. Components
A Classification of Connective Tissues
Connective tissues contain
 Specialized cells
 Matrix
Composed
of extracellular
protein fibers and a ground
substance
Connective tissue proper
 Contains varied cell populations
 Contains various fiber types
 A syrupy ground substance
Fluid connective tissue
 Contains a distinctive cell population
 Watery ground substance with
dissolved proteins
 Two types
 Blood
 Lymph
Supporting connective tissues
 Less diverse cell population
 Dense ground substance
 Closely packed fibers
 Two types
Cartilage
Bone
Connective tissue proper
 Contains fibers, a viscous ground substance,
and a varied cell population
 Fibroblasts
 Macrophage
 Adipocytes
 Mesenchymal cells
 Melanocytes
 Mast cells
 Lymphocytes
 Microphages
The Cells and Fibers of Connective Tissue
Proper
C.T. Continued
6.
Components- 3 types
a.Fibers
i. Collagenous (collegen) fibers – resists
stretching, give strength and
support, compose ligaments and
tendons.
ii. Reticular fibers – much like collagen
fibers, except smaller in size.
iii. Elastic fibers – can stretch
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80
81
C.T. Continued
b. Matrix (aka ground
substance, intercellular, or
interstitutial material,
noncellular substrate)
i. Cell product
ii. Found between cells
iii.Gel, solid, or a fluid
matri
x
83
C.T. Continued
c.Cells – relatively few in number
Connective tissue proper
 Classified as loose or dense
 Loose
 Embryonic
mesenchyme, mucous
connective tissues
 Areolar tissue
 Adipose tissue
 Reticular tissue
 Dense
 Dense regular CT
 Dense irregular CT
Loose Connective Tissue
Connective Tissue: Embryonic
 Mesenchyme – embryonic connective
tissue
 Gel-like ground substance with fibers
and star-shaped mesenchymal cells
 Gives rise to all other connective
tissues
 Found in the embryo
Connective Tissue in Embryos
Connective Tissue: Embryonic
Figure 4.8a
Connective Tissue Proper: Loose
 Areolar connective tissue
 Gel-like
matrix with all three
connective tissue fibers
 Fibroblasts, macrophages, mast cells,
and some white blood cells
 Wraps and cushions organs
 Widely distributed throughout the
body
Connective Tissue Proper: Loose
Figure 4.8b
C.T. Continued
i.
Fibroblasts
a) An active cell engaged in
synthesizing protein for
connective tissue fibers and
matrix.
b)When they become inactive
(mature) they are called
fibrocytes.
C.T. Continued
c)These cells can undergo
transformation into other
types of CT cells if the body
needs demand it.
C.T. Continued
ii. Macrophages
a. Phagecytic cells
b. Amoeboid movement
iii.Mast
cells
a. Contains certain compounds
histamines which control the
dilation of blood vessels and
antibody production.
Connective Tissue Proper: Loose
 Adipose connective tissue
 Matrix
similar to areolar connective tissue
with closely packed adipocytes
 Reserves food stores, insulates against
heat loss, and supports and protects
 Found under skin, around kidneys,
within abdomen, and in breasts
 Local fat deposits serve nutrient needs of
highly active organs
C.T. Continued
iv.Adipose
cells
a)Fat storage
b)Signet ring
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Connective Tissue Proper: Loose
Figure 4.8c
Connective Tissue Proper: Loose
 Reticular connective tissue
 Loose
ground substance with reticular
fibers
 Reticular cells lie in a fiber network
 Forms a soft internal skeleton, or
stroma, that supports other cell types
 Found in lymph nodes, bone
marrow, and the spleen
Connective Tissue Proper: Loose
Figure 4.8d
Adipose and Reticular Tissues
Dense connective Tissue
Connective Tissue Proper: Dense Regular
 Parallel collagen fibers with a few
elastic fibers
 Major cell type is fibroblasts
 Attaches muscles to bone or to
other muscles, and bone to bone
 Found in tendons, ligaments, and
aponeuroses
Connective Tissue Proper: Dense Regular
Figure 4.8e
Connective Tissue Proper: Dense Regular
Figure 4.8f
Dense Connective Tissues
Connective Tissue Proper: Dense Irregular
 Irregularly arranged collagen fibers with
some elastic fibers
 Major cell type is fibroblasts
 Withstands tension in many directions
providing structural strength
 Found in the dermis, submucosa of
the digestive tract, and fibrous organ
capsules
Dense Connective Tissues
Fluid Connective Tissue
Fluid connective tissues
 Distinctive collections of cells in a fluid matrix
 Blood
 Formed
elements and plasma
Red blood cells, white blood cells and
platelets
 Arteries carry blood away, veins carry to
the heart
 Capillaries allow diffusion into the
interstitial fluid
 Lymph
 Interstitial fluid entering the lymphatic
vessels
C.T. Continued
v. Blood
cells (solids,
corpuscles)
a)Erythrocytes– red blood
cells (rbc)
biconcave disk
C.T. Continued
b) Leucocytes – white blood
cells (wbc)
c) Thrombocytes – platelets
Polymorphonuclear
nuclei
Large nuclei
Connective Tissue: Blood
 Red and white cells in a fluid matrix
(plasma)
 Contained within blood vessels
 Functions in the transport of
respiratory gases, nutrients, and
wastes
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Connective Tissue: Blood
Figure 4.8k
Formed Elements of the Blood
Supporting Connective
Tissue
Supporting CT
Osteoblasts (osteocytes)
a) Bone cells
vii.
Connective Tissue: Bone (Osseous Tissue)
 Hard, calcified matrix with collagen
fibers found in bone
 Osteocytes are found in lacunae and are
well vascularized
 Supports, protects, and provides levers
for muscular action
 Stores calcium, minerals, and fat
 Marrow inside bones is the site of
hematopoiesis
Bone, or osseus tissue
 Has osteocytes
Depend
on diffusion
through canaliculi for
nutrients
 Little ground substance
 Dense mineralized matrix
 Surrounded by periosteum
Haversian
System
haversian canal
lacunae
Lamella
(matrix)
canaliculi
osteocyte
Connective Tissue: Bone (Osseous Tissue)
Figure 4.8j
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Osteoblasts (osteocytes)
Bone
Supporting C.T. Continued
vi.Chondroblast
(chondrocytes)
a) Cartilage cells
chondrocyte
matrix
shrinkage space
nucleus
plasma membrane
lacunae
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Supporting connective tissues
 Cartilage and bone support the rest of the body
 Cartilage
 Grows
via interstitial and appositional
growth
 Matrix is a firm gel containing chondroitin
sulfate
 Cells called chondrocytes
 Cells found in lacunae
 Perichondrium separates cartilage from
surrounding tissues
 Three types: hyaline, elastic and
fibrocartilage
Connective Tissue: Cartilage
 Hyaline cartilage
 Amorphous,
firm matrix with imperceptible
network of collagen fibers
 Chondrocytes lie in lacunae
 Supports, reinforces, cushions, and
resists compression
 Forms the costal cartilage
 Found in embryonic skeleton, the end of
long bones, nose, trachea, and larynx
Connective Tissue: Hyaline Cartilage
Figure 4.8g
The Perichondrium and Types of Cartilage
Connective Tissue: Elastic Cartilage
 Similar to hyaline cartilage but with
more elastic fibers
 Maintains shape and structure
while allowing flexibility
 Supports external ear (pinna) and
the epiglottis
Connective Tissue: Elastic Cartilage
 Similar to hyaline cartilage but with more
elastic fibers
 Maintains shape and structure while allowing
flexibility
 Supports external ear (pinna) and the epiglottis
Figure 4.8h
The Perichondrium and Types of Cartilage
Connective Tissue: Fibrocartilage Cartilage
 Matrix similar to hyaline cartilage but
less firm with thick collagen fibers
 Provides tensile strength and absorbs
compression shock
 Found in intervertebral discs (shock
absorbent), the pubic symphysis, and in
discs of the knee joint
Connective Tissue: Fibrocartilage Cartilage
 Matrix similar to hyaline cartilage but less firm
with thick collagen fibers
 Provides tensile strength and absorbs
compression shock
 Found in intervertebral discs, the pubic
symphysis, and in discs of the knee joint
Figure 4.8i
The Perichondrium and Types of Cartilage
Membranes
Membranes are simple organs
 Form a barrier
 Composed of epithelium and connective tissue
 Four types
 Cutaneous
 Synovial
 Serous
 Mucous
Membranes
Mucous membranes
 Line cavities that communicate with
the exterior
 Contain lamina propria
Serous membranes
 Line sealed internal cavities
 Form transudate
Membranes continue
 Cutaneous membrane
Covers
the body surface
 Synovial membrane
Incomplete
cavities
lining within joint
The Connective Tissue Framework of the
Body
Organs and systems are interconnected
 Network of connective tissue proper
consisting of
Superficial fascia
Deep fascia
Subserous fascia
The Fasciae
Nerve Tissue
4. Nerve Tissue
Function: to conduct nerve
impulses
b. Location: found throughout the
body, localized in the brain,
spinal cord, and sense organs.
a.
Nerve Tissue
c.
Classification: ___ types found in
the body.
1. Neuron- conduction cell, conducts
nerve impulses, most prominenet ,
largest of the nerve cells
2. Neuroglia – found only in the
CNS, nutritive and supportive,
most numerous and much smaller
than neurorons.
Nerve Tissue
3.
Neurilemma- aka Schwann cells,
found in the PNS only, cover the
axon of the neuron, supportive,
secretive and necessary for
regeneration of nerve processes.
Cell body
(soma or cyton)
Nissl Bodies
nucleolus
Nucleus
neurofibrils
neurilemma
axon
Node of Ranvier
telodendrites
dendrites
D. Structure: neuron
cell body
(soma or cyton)
Nissl
bodies
nucleolus
nucleus
neurofibrils
neurilemma
axon
Node of Ranvier
telodendrites
dendrites
154
Nerve Tissue
e.
Characteristics and Terminology
associated with nerve tissue:
1. Nerve tissue is incapable of
mitosis- cells for life, if an axon is
damaged and has neurilemma
supporting it, it may regenerate. If
the cell body is damaged, it will
probably die and be lost.
Nerve Tissue
2.
3.
Nerve fibers – clusters or bundles
of axon located in the PNS.
Tracts or pathways – cluster or
bundles of axons located in the
CNS.
Nerve Tissue
4.
5.
Ganglia- cluster of cell bodies in
the PNS
Nuclei- cluster of cell bodies in the
CAN (center)
Nerve Tissue
6.
Myelin sheath- a nerve fiber
which is coated with phospholipid
protein from a neurilemma, has a
whitish appearance, called white
matter.
Myelin sheath
Cellular
sheath
axon
Myelin sheath
Nerve Tissue
7.
Cellular sheath- also formed form
the neurilemma and wrapped around
the axon of the neurons.
Myelin sheath
Cellular
sheath
axon
Myelin sheath
Nerve Tissue
8.
9.
Gray matter – refers to n. fibers
which lack a myelin sheath but has
neurilemma – called amyelinated
Naked fiber – refers to n. fibers
which lack a myelin sheath and
neurilemma.
naked
axon
Processes (dendrites or
telodendrites)
nucleus
nucleolus
Nissle
bodies
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axon
Node of Ranvier
neurilemma
163
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Nervous Tissue
 Branched neurons with long cellular processes




and support cells
Transmits electrical signals from sensory
receptors to effectors
Found in the brain, spinal cord, and peripheral
nerves
Conducts electrical impulses
Conveys information from one area to another
Nervous Tissue
Figure 4.10
Neural tissue cells
 Neurons
 Transmit
information
 Neuroglia
 Support
neural tissue
 Help supply nutrients to neurons
Neural Tissue
Neural anatomy
 Cell body
 Dendrites
 Axon (nerve fiber)
 Carries
information to other neurons
Glands, Secretions
Epithelia: Glandular
 A gland is one or more cells that makes
and secretes an aqueous fluid
 Classified by:
 Site of product release – endocrine or
exocrine
 Relative number of cells forming
the gland – unicellular or
multicellular
Endocrine Glands
 Ductless glands that produce hormones
 Secretes their products directly into
the blood rather than through ducts
 Secretions include amino acids,
proteins, glycoproteins, and steroids
Exocrine Glands
 More numerous than endocrine glands
 Secrete their products onto body
surfaces (skin) or into body cavities
 Examples include mucous, sweat, oil,
and salivary glands
 The only important unicellular gland is
the goblet cell
 Multicellular exocrine glands are
composed of a duct and secretory unit
Multicellular Exocrine Glands
 Classified according to:
Simple
or compound duct type
Structure of their secretory
units
Structural Classification of Multicellular
Exocrine Glands
Figure 4.3a-d
Structural Classification of Multicellular
Exocrine Glands
Figure 4.3e-g
Modes of Secretion
 Merocrine – products are secreted
by exocytosis (e.g., pancreas, sweat,
and salivary glands)
 Holocrine – products are secreted
by the rupture of gland cells (e.g.,
sebaceous glands)
Modes of Secretion
Figure 4.4
Glandular epithelia
 Exocrine glands
Secrete
through ducts onto the
surface of the gland
 Endocrine glands
Release hormones into
surrounding fluid
Glandular secretions can be:
 Merocrine (product released
through exocytosis)
 Apocrine (involves the loss of both
product and cytoplasm)
 Holocrine (destroys the cell)
Mechanisms of Glandular Secretion
Animation: Mechanisms of glandular secretion (check tutorial)
Glands
 Unicellular
Individual
secretory cells
 Multicellular
Organs containing glandular
epithelium
Classified according to structure
A Structural Classification of Exocrine
Glands
Tissue Trauma
Tissue Trauma
 Causes inflammation, characterized
by:
Dilation of blood vessels
Increase in vessel permeability
Redness, heat, swelling, and
pain
Tissue Repair
 Organization and
restored blood supply
 The blood clot is
replaced with
granulation tissue
 Regeneration and
fibrosis
 Surface epithelium
regenerates and the
scab detaches
Figure 4.12a
Tissue Repair
 Fibrous tissue
matures and
begins to
resemble the
adjacent tissue
Figure 4.12b
Tissue Repair
 Results in a
fully
regenerated
epithelium with
underlying scar
tissue
Figure 4.12c
Developmental Aspects
 Primary germ layers: ectoderm,
mesoderm, and endoderm
 Three layers of cells formed early in
embryonic development
 Specialize to form the four primary
tissues
 Nerve tissue arises from ectoderm
Developmental Aspects
 Muscle, connective tissue,
endothelium, and mesothelium
arise from mesoderm
 Most mucosae arise from endoderm
 Epithelial tissues arise from all
three germ layers
Developmental Aspects
Figure 4.13
Tissue Injuries and Aging
Inflammation and regeneration
 Injured tissues respond in
coordinated fashion
 Homeostasis restored by
inflammation and regeneration
Tissue Injuries and Aging
Inflammatory response
 Isolates injured area
 Damaged cells, tissue components
and dangerous microorganisms
removed
Infection avoided
 Regeneration restores normal
function
An Introduction to Inflammation
Aging and tissue repair
 Change with age
 Repair and maintenance less
efficient
 Structure altered
 Chemical composition altered
Aging and cancer incidence
 Incidence of cancer increases with
age
 70-80% of all cases due to
exposure to chemicals or
environmental factors
Changes in a Tissue under Stress