Animals tissue

Animal cells and tissues

1.Epithelial cells 3.Muscle cells

2.Nerve cell 4.Connective tissues

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Epithelial Cells

• The cells are
firmly attached to
each other

• Lining tissues :
cover the surface
of the body
(outer layer of
the skin), or lines
a cavity such as
lumen of an
intestine

FUNCTIONS

• Main function : protection (E.g. epithelial layer of skin covers
the entire body and protects from mechanical injury,
chemicals, bacteria and fluid loss

• Other functions:

Absorption (through the epithelium of the gut and enters
the blood)

Exchange materials by diffusion (CO2 and O2 through
alveoulus)

Secretion (as a gland) :secrete mucus or enzyme

Epithelial Cells

1.Simple squamous Consist of single
2.Simple cuboidal layer of cells
3.Simple columnar Consist of several
4. Stratified squamous layers

Simple squamous epithelial cells

Structures :

• Cells are flattened.

• Thin layer Basement
• Single layer cells membrane
• Disk shaped central nuclei
• Attached to the basement membrane
• The sheet of cell is delicate, thin and leaky.

Functions:

 Diffusion of materials through it (alveoli of the walls and

blood capillary walls)

 Lubricates the movement between adjacent surfaces

Distribution:
• linings of blood vessels/ /blood

capilary walls
• alveoli of the lungs
• mouth cavity
• Bowman capsule

Simple cuboidal epithelial cells

Structures:
 Cubical in shape
 Single layer cells
 Have a central spherical nucleus
 View from the surface cells are

polygonal.

Functions :
 Specialized for secretion and absorption.
 Secretes and reabsorbs water

and small molecules

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Distribution

•Lining of kidney
tubules

•Lining of gland ducts:
thyroid & salivary
glands

Simple columnar epithelial cells

Structures:
• Elongated cell (tall and

quite narrow)
• Single layer cells
• Relatively large cytoplasmic

volume.
• Nucleus oval shape at its

basal end
• Some cell have cilia &

microvilli

Functions:

•Secretion of mucus
•Absorption of nutrients
•Thicker cell layer provides
protection
• Ciliated types:
• To move substance
• Filtering of foreign particles
in trachea
• Microvili types:
• Increase surface area for
reabsorption.

Distributions:

• Linings of small
intestine / much
digestive tract

• Upper part of
respiratory part

• Oviduct (fallopian
tube)

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Stratified Squamous Epithelial Cells

Structure

• Several layer of cells
(two or more layers of cell)

• Surface cells are flattened
• Division of lower cells

causes older one to pushed
upward forward surface,
becoming flattened as they
move
• The lower ones columnar
and metabolically active

Stratified Squamous Epithelial
Cells

Function
• Protect against

abrasion, drying out
and infection

Distribution
• Main location –

Outer layer of skin,
mouth and vaginal
lining
• Lining of esophagus





Nerve Cell ( Motor neuron )

Dendrites Cell Body Myelin
Sheath

Axon of another Axon Dendrites of another
neuron neuron

STRUCTURE OF NEURON

Motor neurons:

Distribution: Brain and
spinal cord

• Function: • Receive nerve
impulses from interneurons
and transmit impulses to
effector organs (muscle and
gland).

• Specialized to produce and
conduct electrochemical
events or impulses.

• Neurons provide
communication between
receptors and effectors.





Structure of cell
body:

• A neuron consists
of a cell body
(largest portion of
a neuron)
containing a
nucleus and the
perikaryon, which
is the cytoplasm
and organelles
surrounding the
nucleus

• In vertebrates, the
axons of many neurons
outside the CNS (central
nervous system) are
surrounded by a series
of Schwann cells that
form an insulating
covering – myelin
sheath

• Gaps in the myelin
sheath – nodes of
Ranvier (the axon is not
insulated with myelin)
occur between
successive Schwan cells



MUSCLE TISSUE

Striated/Skeletal Muscle

Structure
• The cells are elongated and cylindrical
• Blunt ends
• Possess many nuclei (multinucleate) per fiber, located in the

periphery of the cells
• Unbranched
• The striations are a result of the orderly arrangement of

actin and myosin filaments within the muscle
Function: responsible for voluntary movement
Distribution: attached to bones by tendons



STRUCTURE OF A STRIATED MUSCLE

sarcoplasm

•The membrane for muscle fibre is called sarcolemma
•Its cytoplasm is sarcoplasm which contain many
mitochondria
•Myofibril consists of

 myosin (thick filament)
 actin (thin filament)

Smooth muscle

Structure
• Spindle shaped, elongated and pointed ends
• No striation
• Position of nuclei is central
• Number of nuclei per fiber is one
• Contract more slowly than skeletal muscle, can contract

rythmically like peristalsis.
Function: responsible in involuntary activities.
Distribution: walls of internal organs - digestive tract,

urinary bladder etc.

Cardiac muscle

Structure
• Striated like skeletal muscle but have branches.
• The ends of the cells are joined by intercalated disc
• Intercalated disc allow communication between the

cardiac cells for sequential contraction
• One or two nuclei per fiber
• Nuclei are centrally
Function: myogenic contraction of wall of the heart.
Distribution: cardiac tissue of the wall of the heart



Connective tissues

• The major types
of connective
tissues in
vertebrates are:
a) Compact
Bone
b) Hyaline
cartilage
c) Blood

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COMPACT BONE TISSUE

Bone are divided into TWO types:
1.Compact Bone
2.Spongy Bone

Spongy Compact
bone bone

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Model of the compact bone

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• A typical bone has
an outer layer of
compact bone
surrounding
spongy bone

cartilage

Spongy bone
Compact bone

Compact bone lacuna
osteocyte
Structure
• Consists of hard matrix

which is made up of collagen
fiber and inorganic material
which is secreted by
osteoblast
• The combination of hard
mineral and flexible
collagen makes bones
harder than cartilage.

• Osteocyte is mature bone
derived from osteoblast

• Osteocyte is found in lacuna

Compact bone lacuna
osteocyte
Structure

• Osteoblast function to

secrete bone matrix.

• Osteoblast become less

active when they matured

and known as osteocytes.

• Osteocyte is found in
lacuna.

• Osteocytes function for
bone deposition and
resorption. .

• It is made up of numerous
cylinders.

• Each cylinder is a Harvesian
system or osteon

• Each Harvesian system is
made up of concentric
circles called lamellae
around a Harvesian canal,
containing blood vessel
(artery and vein) and
nerve

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• The blood vessels allowcanaliculi lacuna
the exchange of osteocyte
materials with the bone
cells (nutrien, metabolic
wastes and respiratory
gases)

• Fine channels called
canaliculi contain
cytoplasmic strands
which connect lacunae
to each other

• Canaliculi is for nutrient
and gas exchange
between the bone cells

Blood vessel

Blood
vessel

Haversian
canal

canaliculi Lacuna

Osteon

osteocyte 40

• Volkmann canals connect
the Harvesian of adjacent
osteons to each other.

Volkmann canal

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• Distribution : form skeletal structure in most
vertebrates

• Functions:
1) Give body shape and provide
framework for support e g. skeleton
2) Act as reservoir for calcium and phosphorus
3) Support and protect the internal organ
4) Skeletal muscles attach to bones

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Hyaline Cartilage
Structure
• Elastic and compressible tissue
• Chondrocyte secrete matrix and

chondroitin sulphate

• The matrix is a semi transparent
materials

• The matrix of hyaline cartilage
known as chondrin which give soft
and elastic characteristic

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• Chondrocytes found
in lacunae

• The cartilage is
protected by an outer
perichondrion layer

• The perichondrium
produces the new
Chondrocytes which
secrete the cartilage
matrix (chondrin).

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• Distribution :
Nose, trachea, ends of
some bones and bronchi
.

• Function:
1)
2) Cover the ends of
bone and reduces
friction between
joints during
movement

3) For flexible support

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Differences between cartilage and
bone tissue

Cartilage Bone

Cartilage cell is called Bone cells is called
Chondrocytes Osteoblasts

Lacunae are not Lacunae are connected to
connected to each other each other by canaliculi

Chondroblasts are Osteoblasts contained in
function to secrete the cartilage matrix lacunae and function for bone deposition

(chondrin) and and resorption.in
contained in a space called concentric layer called

capsular lacuna lamellae

Differences between cartilage and
bone tissue

Cartilage Bone
Matrix is collagenous Matrix is very strong,
and elastic/flexible
Dense and hard
No blood vessel, lymph calcified
vessel and nerve fibres
(present only inside the Have blood vessel, lymph
perichondrion layer) vessel and nerve fibres in
Have collagen and elastin
the Harvesian canal
fibrils
Have only collagen fibrils

Function to reduces friction at Function is to provide
joins,movement,support and growth. mechanical support, to
protect internal organ

Connective tissue: Blood

BLOOD TISSUE

BLOOD CELL - 45% PLASMA – 55%

RED BLOOD CELLS SERUM
(ERYTHROCYTES) FIBRINOGEN

WHITE BLOOD CELLS
(LEUKOCYTES)

PLATELETS
(THROMBOCYTES)

TYPES OF
BLOOD CELL

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