Download Connective Tissue

Anatomy and physiology
advice to clients
Connective tissue
Connective tissue or supporting
tissue
• The human body is held together by a
range of tissues that have been
traditionally called connective tissue. In
each of these tissues there are specialised
cells that manufacture this connective
tissue. In this session we shall look at the
cells which synthesise connective tissue
as we investigate different types of
connective tissue.
Loose connective tissue
• Loose connective tissue is composed of loose collagen
bundles, occasional fibroblasts and adipose cells.
Collagen is a special protein found in connective tissue.
The fibroblast cells make the collagen bundles and they
replace it when it is damaged or manufacture new tissue
as the body grows. You can see the loose connective
tissue under the epithelial layer in this section of gut.
Dense connective tissue
• Dense connective tissue lays down layers of
collagen bundles in sheets. It is used when
strength is required. This is a section of tendon
magnified about 100 times. Tendons join
muscles to bones. You can see the occasional
fibroblast in this section as small blue cells and
you can see the wavy nature of the collagen
bundles
Fibroblasts
• Fibroblasts are the specialised cells that
manufacture collagen. You can see here in this
electron micrograph the fibroblasts that are
actively synthesising collagen. Look closely
and you will see long parallel collagen fibrils that
have been synthesised. Look at the cell in the
middle, note the nucleus and the threads of
collagen being extruded from the cytoplasm of
the cell. This slide has been magnified about
200,000 times.
Elastic fibres
• Elastic fibres are widespread throughout the
body where elasticity is required. Elasticity is
required when a tissue has to return to an
original shape and size after changing shape.
Elastic fibres are made of several proteins, one
of which is elastin. These fibres spring back to
the original shape after being deformed. This is
a cross section of an elastic artery. These
arteries can expand and contract in response to
changes in blood pressure. This slide has been
magnified about 1000 times and stained with a
special dye to show the wavy elastic fibres.
Elastic fibres
• If you pinch your skin you will note that it
immediately falls back into place. Elastic fibres
in the dermis of the skin restore skin to its
original shape very quickly. You can see these
fibres as blue threads in this slide. It has been
magnified about 500 times. As you get older the
elastic fibres start to degrade. That’s why older
people have wrinkles! Apply the pinch test to
your skin and note how it springs back to shape
immediately after you let go.
Reticular fibres
• Reticular fibres are also produced by fibroblasts
and they are a different type of collagen. They
form a network of fibres that support the cells.
Cells have a 3D volume and some require
support. This picture shows reticular fibres in a
lymph node magnified about 500 times.
Incidentally, reticulum means net and you can
see a net of fibres in this slide
Adipose cells
• The cytoplasm of the adipose cell (or fat cell)
contains triglycerides which is the fat that is laid
down in our body. Adipose cells are cells and so
must have a nucleus. The nucleus is often at
the periphery of the cell and if you look carefully
you can see some nuclei. Adipose cells are often
supported by loose connective tissue. In the top
right hand corner of this slide you can see a
small blood vessel which reminds us that all
cells in our body are served by a blood supply
Tendons
• Tendons are also composed of collagen
and link muscle to bone and muscle to
muscle. You can see in this slide of a
tendon the crimped pattern of collagen
fibres forming ribbons in the tendon. Look
carefully at where a muscle joins a tendon.
It actually forms little anchor sites where
the tendon and muscle join. In this slide
you can see muscles and tendon.
Ligaments
• Ligaments are also composed of collagen fibres
but you can see that these fibres are separated
by a matrix between the fibres. Ligaments join
bones together to form a joint. In this slide you
can see ligament joining two vertebrae. Look
closely and you will see elastic fibres. This gives
this ligament additional flexibility. In these two
slides you can see ligaments in situ.
Hyaline cartilage
• Cartilage provides a smooth surface for joint
movement and a framework for bone growth.
Chondrocytes are cells that make up cartilage
and secrete a collagen matrix. Hyaline cartilage
is the most widespread type of cartilage. We will
look at hyaline cartilage in more detail when we
look at skeletal tissues. Incidentally, hyaline
means “glassy” and yes, when you look at it
under a microscope it does look glassy just like
the slide here
Elastic cartilage
• Elastic cartilage is found in the ear and epiglottis. Move
your ear back and forward. You can feel that it returns to
its shape after moving and you can feel that it is a rigid
structure without being too rigid. It’s amazing isn’t it?
This type of cartilage contains both collagen and elastic
fibres. This is a microscope section of an ear. You can
also see skin on the right hand side, elastic cartilage,
adipose cells and skeletal muscle on the left
Fibrocartilage
• Fibrocartilage is composed of
abundant collagen bundles. It
is primarily found in in
vertebral discs between the
vertebra of the spine
• It is also found in the hip joint.
Hormones soften this joint in
pregnancy to help the birth
process
• In the next slide you can see
vertebral disks. The
fibrocartilage in these disks
absorb both downwards and
sideways pressure on your
vertebrae
Other connective tissue
• Bone and blood are generally regarded as
connective tissue
• We will deal with these tissues as
separate lessons
Activity
• Prepare some diagrams and brief notes on
each of the connective tissues covered in
this session so that you can explain the
nature of these tissues to clients if you are
requested to do so.