Tissue Organisation in the Body
A&P 1
Tutor: Eleshia Howell
1
Written by Eleshia Howell for use by AoCH -WEA
Hunter.(c) 2012. Not to be used without the express
permission of the Author.
Chapter 3 – from p34, Ross & Wilson:
Tissues are collections of cells and cell products that perform
specialised, yet limited functions according to their type.
There are four main types of tissues, each with their own subdivisions.
1. Epithelial – covers the body (skin) and lines cavities, hollow
organs and tubes, and is also found in Glands.
2. Connective – fills internal spaces, supporting other tissues;
transports material; stores energy.
3. Muscle – specialised for contraction
4. Nerve – carries electrical signals from one part of the body to
another.
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Written by Eleshia Howell for use by AoCH -WEA Hunter.(c) 2012. Not to be used without the express
permission of the Author.
Epithelial Tissue
 The structure of epithelial tissue is closely related to its
functions, which include:
 Protection of underlying structures
 Secretion
 Absorption
 The cells are very closely packed and the intercellular
substances, or matrix, is minimal.
 May be simple (a single layer of cells) or stratified (several
layers of cells.
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Written by Eleshia Howell for use by AoCH -WEA Hunter.(c) 2012. Not to be used without the express permission
of the Author.
Simple Epithelium
 Consists of a single layer of identical cells, sub-divided into 3
main types which are named according to their function. The
more active the tissue, the taller the cells.
 It is usually found on secretory surfaces.
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Written by Eleshia Howell for use by AoCH -WEA Hunter.(c) 2012. Not to be used without the express permission
of the Author.
Squamous – composed of a single layer of flattened cells, fitting
closely together like a pavement, forming a thin, smooth
membrane across which diffusion occurs easily. It forms the
lining of the following structures
 Heart (endocardium)
 Blood and lymph vessels ( endothelium)
 Alveoli of the lungs
 Ducts of the kidneys
Cuboidal – cube shaped cells on a basement membrane, actively
involved in secretion, absorption and excretion. Found in
tubules of the kidneys, sweat ducts, mammary glands and some
glands.
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Written by Eleshia Howell for use by AoCH -WEA
Hunter.(c) 2012. Not to be used without the express
permission of the Author.
Columnar – rectangular shaped cells, on a basement membrane,
which lines many organs. Can have ancillary structures, such as
microvilli and goblet cells, to enhance the function of its
location. For example, columnar cells line the small intestine
and have microvilli which increase the surface area of the organ,
enabling an increased absorption of water and nutrients. In the
trachea, the cells are ciliated (have hair like projections) which
collect inhaled particles to be moved towards the throat.
Stratified – consists of several layers of cells of various shapes, to
help protect underlying structures from mechanical wear and
tear. Sub-divided into two types: Stratified Squamous (mainly
columnar, with squamous at the top where it can be shed) and
Transitional (irregular, pear shaped cells allowing for stretch in
the tissue).
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Written by Eleshia Howell for use by AoCH -WEA Hunter.(c) 2012. Not to be used without the express
permission of the Author.
Connective Tissue
 The most abundant tissue found in the body
 Tissue cells are more widely separated and matrix is present in
considerably larger amounts.
 Usually fibres present in the matrix too, forming a supportive
network for the cells to attach to.
 Most have a good blood supply.
 Four main functions:
1. Binding & structural support
2. Protection
3. Transport
4. insulation
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Written by Eleshia Howell for use by AoCH -WEA Hunter.(c) 2012. Not to be used without the express
permission of the Author.
Connective tissue, excluding blood, is found in all organs
supporting the specialised tissues.
The different types of cells involved include:
 Fibroblasts
 Fat cells (adipocytes)
 Macrophages
 Leukocytes
 Plasma cells
 Mast cells
Let’s take a look at these individually....
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Written by Eleshia Howell for use by AoCH -WEA Hunter.(c) 2012. Not to be used without the express
permission of the Author.
Fibroblasts
Large cells with irregular processes,
they produce collagen and elastic fibres.
They are very active in tissue repair
where they can bind together the
broken surfaces of a wound, or form
granulation tissue where tissue has
been destroyed.
Collagen fibres shrink as they grow
old, resulting in adhesions.
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Written by Eleshia Howell for use by AoCH -WEA
Hunter.(c) 2012. Not to be used without the express
permission of the Author.
Fat Cells
Each cell stores a single large fat
droplet and can occur singly in
tissue or in groups. They are
especially abundant in Adipose
(Fat) tissue and can vary in size /
shape depending on where they
are located.
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Written by Eleshia Howell for use by AoCH -WEA
Hunter.(c) 2012. Not to be used without the express
permission of the Author.
Macrophages
Large irregular shaped cells that act
as part of the immune system,
engulfing and digesting cellular
debris, foreign bodies and bacteria
(phagocytosis).
Some are fixed (attached) to
connective tissue fibres and other
roam freely.
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Written by Eleshia Howell for use by AoCH -WEA
Hunter.(c) 2012. Not to be used without the express
permission of the Author.
Leukocytes
Also known as White Blood
Cells (WBC’s).
Normally found in small
numbers in healthy connective
tissue , but as they play a major
role in the immune system,
become more prolific during
an infection.
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Written by Eleshia Howell for use by AoCH -WEA
Hunter.(c) 2012. Not to be used without the express
permission of the Author.
Mast Cells
 Found in loose connective tissue, under the fibrous
capsule of organs and in considerable amounts around
blood vessels.
 They are another aspect of the immune system
response, producing tiny granules of Heparin (to reduce
blood clotting) and Histamine (to reduce inflammatory
reactions) to mediate the inflammation process and
allergic reactions.
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Written by Eleshia Howell for use by AoCH -WEA
Hunter.(c) 2012. Not to be used without the express
permission of the Author.
Other cells found in Connective Tissue
include:
 Melanocytes – synthesizes and stores the brown pigment
melanin.
 Mesenchymal cells – stem cells that respond to injury or
infection; can differentiate into various forms of cells as
required, eg Fibroblasts, Macrophages etc.
 Lymphocytes – specialised immune cells in Lymphoid tissue
 Microphages – small phagocytic blood cells, eg Eosinophils,
Neutrophils.
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Written by Eleshia Howell for use by AoCH -WEA
Hunter.(c) 2012. Not to be used without the express
permission of the Author.
Loose (areolar) Connective Tissue
 The most generalised type of connective tissue, found almost
in every part of the body, providing elasticity and tensile
strength.
 It connects and supports other tissues, such under the skin,
between muscles, blood vessels and nerves, and the
alimentary canal.
 See fig 3.16 on p36 Ross & Wilson
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Written by Eleshia Howell for use by AoCH -WEA
Hunter.(c) 2012. Not to be used without the express
permission of the Author.
Adipose Tissue
 Consists of fat cells in a matrix of areolar tissue.
 Two types: White and Brown
 White adipose tissue makes us 20-25% of body weight in a
well-nourished adult. It is found supporting organs, between
muscle fibres and under the skin, where it acts as insulation
and an energy store.
 Brown adipose tissue is present in Newborns and has a more
extensive blood supply. When it metabolises, it produces less
energy and more heat, helping to maintain body
temperature.
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Written by Eleshia Howell for use by AoCH -WEA Hunter.(c) 2012. Not to be used without the express
permission of the Author.
Dense Connective Tissue
 Contains more fibres and fewer cells than loose connective tissue.
 Two types: Fibrous and Elastic
 Fibrous tissue is made up of closely packed bundles of collagen
fibres with very little matrix. This kind of tissue is found in
Ligaments, the Periosteum, as an outer protective layer on organs
and forms muscle sheaths which extend beyond the muscle to
become Tendons.
 Elastic tissue is capable of considerable extension and recoil.
Therefore it has fewer cells and more elastic fibres in the matrix.
It is found in organs and structures where alteration of shape is
required, eg: lungs, arteries, bronchi.
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Written by Eleshia Howell for use by AoCH -WEA Hunter.(c) 2012. Not to be used without the express
permission of the Author.
Blood
 This is a fluid connective tissue and is discussed in more detail
in weeks 13 & 14.
Cartilage
 Is firmer than other connective tissues.
 Cells are called Chondrocytes and are less numerous,
embedded in matrix reinforced by collagen and elastic fibres
 There are 3 types of cartilage:
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Written by Eleshia Howell for use by AoCH -WEA Hunter.(c) 2012. Not to be used without the express permission
of the Author.
Hyaline Cartilage:
Smooth, bluish-white tissue provides flexibility, support and
smooth surfaces for bone movements. It is found –
 At the end of long bones
 Costal (rib) cartilage
 Parts of the larynx, trachea and bronchi.
Fibrocartilage:
A tough, slightly flexible supportive tissue found –
 Intervertebral discs
 Between articulating surfaces of joints
 On the rim of bony sockets, eg hip and shoulder
 As Ligaments, joining bone to bone.
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Written by Eleshia Howell for use by AoCH -WEA Hunter.(c) 2012. Not to be used without the express
permission of the Author.
Elastic Fibrocartilage:
Flexible tissue provides support and maintains the shape of a
structure, eg ear lobe, epiglottis and internal blood vessel
walls.
Bone
Bone cells, called Osteocytes, are surrounded by a matrix of
collagen fibres strengthened by inorganic salts, eg calcium and
phosphate. This provides bone with the its strength and rigidity.
Bone has considerable capacity for growth and regeneration.
There are two types of Bone:
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Written by Eleshia Howell for use by AoCH -WEA
Hunter.(c) 2012. Not to be used without the express
permission of the Author.
 Compact Bone – is solid, or dense in appearance.
 Spongy or Cancellous Bone – has a fine, honeycomb
appearance.
 Bone is discussed in more detail in week 11 when we look at
the Skeleton.
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Written by Eleshia Howell for use by AoCH -WEA
Hunter.(c) 2012. Not to be used without the express
permission of the Author.
Muscle tissue
 Is able to contract and relax, providing movement within and
of the body.
 Muscle contraction requires an adequate blood supply to
provide oxygen, calcium and nutrients and to remove waste
products.
 There are 3 types of specialised muscle cells:
1. Skeletal
2. Smooth
3. Cardiac
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Written by Eleshia Howell for use by AoCH -WEA Hunter.(c) 2012. Not to be used without the express
permission of the Author.
Skeletal Muscle
 Forms the muscles that move the bones of the skeleton
 Are striated (striped)
 Are voluntary – you can move them at will
 May be consciously (e.g.writing)or sub-consciously controlled
(e.g.breathing)
 Fibres are cylindrical, contain several nucleii and can be up to
35cm long.
 Contraction is stimulated by motor nerve impulses, originating
in the brain or spinal cord, and ending at the neuromuscular
junction (where nerve meets muscle tissue)
23
Written by Eleshia Howell for use by AoCH -WEA Hunter.(c) 2012. Not to be used without the express
permission of the Author.
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Written by Eleshia Howell for use by AoCH -WEA Hunter.(c) 2012. Not to be used without the express
permission of the Author.
Smooth Muscle
 Is described as non-striated, visceral or involuntary.
 Has the intrinsic ability to contract and relax, although it is
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usually only relaxed for very short periods of time.
Contraction is slower and more sustained.
Autonomic nerve impulses, some hormones and local
metabolites stimulate contraction.
Found in the walls of hollow organs, eg: blood vessels, uterus,
ducts, glands etc.
The cells are spindle shaped, with only one nucleus.
The muscle fibres are generally bundled together to form a
sheet of muscle.
Written by Eleshia Howell for use by AoCH -WEA Hunter.(c) 2012. Not to be used without the express
permission of the Author.
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Written by Eleshia Howell for use by AoCH -WEA Hunter.(c) 2012. Not to be used without the express
permission of the Author.
Cardiac Muscle
 Found only in the heart wall.
 Involuntary
 Has striations, similar to skeletal muscle
 Each fibre has a nucleus and one or more branches, which is
in very close contact with adjacent cells. Microscopically,
these joins or intercalated discs, can be seen as lines that are
thicker and darker than ordinary muscle striations.
 The significance of the closely aligned structure is that it
allows the wave-like contraction of a heart beat (individual
cells do not need to be stimulated to contract).
27
Written by Eleshia Howell for use by AoCH -WEA
Hunter.(c) 2012. Not to be used without the express
permission of the Author.
28
Written by Eleshia Howell for use by AoCH -WEA Hunter.(c) 2012. Not to be used without the express
permission of the Author.
Nerve Tissue
 Two types of tissue are found in the nervous system:
Excitable cells – called neurones, they initiate, receive,
conduct and transmit information
2. Non-excitable cells – known as glial cells, these support
the neurones.
1.
More on nerve cells will be discussed in week 4.
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Written by Eleshia Howell for use by AoCH -WEA Hunter.(c) 2012. Not to be used without the express
permission of the Author.
Membranes
 Membranes are sheets of tissue that cover or line surfaces or
separate organs or parts of organs from each other. Many
membranes provide specialized secretions.
 The two groups of membranes we will look at are:
 Epithelial Membranes – further subdivided into Mucous and
Serous
 Synovial Membranes – these line cavities of moveable joints and
also surrounds tendons that are in close contact with bony
structures. It consists of areolar connective tissue and elastic
fibres. It secretes clear, sticky, oily synovial fluid which
lubricates and nourishes the joints.
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Written by Eleshia Howell for use by AoCH -WEA Hunter.(c) 2012. Not to be used without the express
permission of the Author.
 Mucous Membranes – sometimes referred to as mucosa, this lines the
alimentary, respiratory and genitourinary tracts. Some of the epithelial
cells on the surface of a membrane are actually Goblet cells, which
produce mucous – when the cell fills up with the mucous, it bursts and
discharges the fluid.
This is why mucous
membranes appear moist
and slippery; this helps to
protect the membrane and
in areas such as the
respiratory tract, even helps
to trap foreign particles from
entering the lungs.
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Written by Eleshia Howell for use by AoCH -WEA Hunter.(c) 2012. Not to be used without the express
permission of the Author.
 Serous Membrane – sometimes referred to as Serosa, consist of
a double layer of loose areolar connective tissue lined by simple
squamous epithelium. The parietal layer lines a cavity and the
visceral layer surrounds organs (viscera) within the cavity.
Serous membranes secrete serous fluid, decreasing friction as
the surfaces of organs glides across other tissue or organs.
There are three sites where serous membranes are found:
 The Pleura lining of the thoracic cavity and surrounding the lungs
 The Pericardium lining the pericardial cavity and surrounding the
heart
 The Peritoneum lining the abdominal cavity and the surrounding
the abdominal organs.
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permission of the Author.
Glands see p41 Ross & Wilsom
 Groups of epithelial cells that produce specialised
secretions.
 Glands that secrete (directly or indirectly) through a duct
are known as EXOCRINE glands
 Glands that secrete into blood and lymph are called
ENDOCRINE glands and the substance is called a
Hormone.
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Written by Eleshia Howell for use by AoCH -WEA Hunter.(c) 2012. Not to be used without the express
permission of the Author.
A Salivary gland – example of an exocrine gland (ducts)
34
Written by Eleshia Howell for use by AoCH -WEA Hunter.(c) 2012. Not to be used without the express
permission of the Author.
Endocrine Glands found in the Human Body
(will be covered in weeks 8 and 9)
35
Written by Eleshia Howell for use by AoCH -WEA Hunter.(c) 2012. Not to be used without the express
permission of the Author.
Tissue Repair
 Tissues respond to damage or injury via two processes:
 Inflammation – the inflammatory response is the first response
to injury.
 Regeneration – begins when the initial inflammation phase is
complete and any infection has been “cleaned up”.
36
Written by Eleshia Howell for use by AoCH -WEA
Hunter.(c) 2012. Not to be used without the express
permission of the Author.
Inflammatory Response (p367-369 Ross & Wilson)
 Can be triggered by trauma to the tissue, chemical / toxic
agents or infection (invasion of pathogens).
 Signs and symptoms of inflammation are:
 Redness
 Heat
 Pain
 Swelling
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Written by Eleshia Howell for use by AoCH -WEA
Hunter.(c) 2012. Not to be used without the express
permission of the Author.
Regeneration
 Once phagocytosis is complete, Fibroblasts secrete collagen
fibres to form scar tissue
 A ‘maturation’ process begins where the collagen fibres are
gradually replaced with new tissue, helped by somatic stem
cells (mesenchymal cells) which produce the right type of
tissue needed for the site.
 Some tissue regenerates better than others – epithelia and
connective tissue regenerate well, whereas cardiac and nerve
tissue does not (or does so very poorly).
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Written by Eleshia Howell for use by AoCH -WEA
Hunter.(c) 2012. Not to be used without the express
permission of the Author.
Effects of Aging on Tissue Repair
 The speed and efficiency of tissue repair decreases with age
due to:
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Slower rate of energy consumption (metabolism)
Hormones
Reduced physical activity
Altered nutritional intake
Build up of free-radical damage
 The effects are:
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Thinning of epithelial and connective tissues
Increased bruising and bone brittleness
Joint pain / bone fractures
Cardiovascular disease
Mental deterioration
Written by Eleshia Howell for use by AoCH -WEA Hunter.(c) 2012. Not to be used without the express
permission of the Author.
Summary:
You should now have a general understanding of the different
types of tissue present in the human body and their functions,
not only on a cellular level, but for the organism as a whole.
40
Written by Eleshia Howell for use by AoCH -WEA
Hunter.(c) 2012. Not to be used without the express
permission of the Author.