Connective Tissue
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Connective tissue
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It is one of the four general classes of tissues
Connective tissue (CT) is a tissue that supports,
connects, or separates different types of tissues
and organs of the body.
Connective tissue is found everywhere including in
the central nervous system. It is located in
between other tissues
G.LUFUKUJA
Connective tissue
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All connective tissue except (blood and lymph) consists of
three main components:
fibers (reticular, elastic and collagenous fibers),
ground substance and
Cells (fibroblasts, adipocytes, macrophages, mast cells and
leucocytes)
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MEDICAL APPLICATION
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The regenerative capacity of the connective tissue is clearly
observed when tissues are destroyed by inflammation or traumatic
injury.
In these cases, the spaces left after injury to tissues whose cells
do not divide (eg, cardiac muscle) are filled by connective tissue,
which forms a scar. The healing of surgical incisions depends on
the reparative capacity of connective tissue. The main cell type
involved in repair is the fibroblast.
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MEDICAL APPLICATION…
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Collagen synthesis depends on the expression of several
genes and several posttranslational events. It should not be
surprising, therefore, that a large number of pathological
conditions are directly attributable to insufficient or abnormal
collagen synthesis
Keloid is a local swelling caused by abnormal amounts of
collagen that form in scars of the skin
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MEDICAL APPLICATION…
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Vitamin C (ascorbic acid) deficiency leads to scurvy, a disease
characterized by the degeneration of connective tissue. Without
this vitamin, fibroblasts synthesize defective collagen, and the
defective fibers are not replaced.
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MEDICAL APPLICATION…
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Edema is promoted by the accumulation of water in the
extracellular spaces. Water in the extracellular compartment of
connective tissue comes from the blood, passing through the
capillary walls into the extracellular compartment of the tissue
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CLASSIFICATION OF CT
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Classification is based on the density and organization of the
connective tissue cells and fibers. The composition of
connective tissue also reflects the functions of particular
tissues or organs.
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Loose CT
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Loose connective (areolar) tissue: Contains more
cells than fibers and the fibers are thinner,
delicate, sparse and loosely arranged
Areolar connective tissues hold organs in place
and attaches epithelial tissue to other underlying
tissues. It also surrounds the blood vessels and
nerves
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Dense CT
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Dense connective tissue is mainly composed of type I
collagen. Crowded between the collagen fibers are
rows of fibroblasts, fiber-forming cells, that
manufacture the fibers.
Dense connective tissue forms strong, rope-like
structures such as tendons and ligaments. Tendons
attach skeletal muscles to bones; ligaments connect
bones to bones at joints. Ligaments are more stretchy
and contain more elastic fibers than tendons. Dense
connective tissue also make up the lower layers of the
skin (dermis), where it is arranged in sheets
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Dense CT…
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The specialized connective
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Adipose tissue is a special type of connective tissue in
which adipose (L. adeps, fat) cells (adipocytes)
predominate
Adipose tissue is the largest repository of energy (in
the form of triglycerides) in the body. The other organs
that store energy (in the form of glycogen) are the liver
and skeletal muscle
Subcutaneous layers of adipose tissue help to shape
the surface of the body, whereas deposits in the form of
pads act as shock absorbers, chiefly in the soles and
palms. Because fat is a poor heat conductor, it
contributes to the thermal insulation of the body
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Adipose tissue…
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Unilocular (yellow) adipose tissue is composed of cells
that, when completely developed, contain one large central
droplet of yellow fat in their cytoplasm. Multilocular (or
brown) adipose tissue is composed of cells that contain
numerous
lipid
droplets
and
abundant
brown
mitochondria. Both types of adipose tissue have a rich
blood supply
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Adipose tissue…
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Yellow adipose tissue is found throughout the human
body except for the eyelids, the penis, the scrotum,
and the entire auricle of the external ear except for the
lobule. Age and sex determine the distribution and
density of adipose deposits
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MEDICAL APPLICATION
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Obesity in adults may result from an excessive
accumulation of fat in unilocular tissue cells that
have become larger than usual (hypertrophic
obesity). An increase in the number of adipocytes
causes hyperplastic obesity
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Specialized CT:
bone and cartilage
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Cartilage is a specialized form of connective tissue in
which the firm consistency of the extracellular matrix
allows the tissue to bear mechanical stresses
without permanent distortion
Cartilage consists of cells called chondrocytes (Gr.
chondros, cartilage, + kytos, cell) and an extensive
extracellular matrix composed of fibers and ground
substance
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Specialized CT:
cartilage
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Classification of cartilage
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There are three types of cartilage that are
distinguished by the light microscope based on the
types of fibers it contains, the composition of the
ground substance and density and arrangement of
cells.
Hyaline cartilage (glass-like)
Elastic cartilage
Fibrocartilage
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Location of hyaline cartilage
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Hyaline cartilage is located in the
 Wall of the upper airway i.e. nose, larynx,
trachea, bronchi,
 The sternal ends of ribs, (costal cartilages) and it
also covers the articular surfaces of joints.
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Elastic cartilage
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Elastic cartilage is found in the auricle of the ear, the
walls of the external auditory canals, the auditory
(eustachian) tubes, the epiglottis, and the cuneiform
cartilage in the larynx. Elastic cartilage is essentially
identical to hyaline cartilage except that it contains an
abundant network of fine elastic fibers in addition to
collagen type II fibrils
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Fibrocartilage
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Fibrocartilage is a tissue intermediate between dense connective
tissue and hyaline cartilage.
It is found in intervertebral disks, in attachments of certain
ligaments to the cartilaginous surface of bones, and in the
symphysis pubis.
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Fibrocartilage…
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MEDICAL APPLICATION
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Rupture of the annulus fibrosus, which most
frequently occurs in the posterior region
where there are fewer collagen bundles,
results in expulsion of the nucleus pulposus
and a concomitant flattening of the disk.
As a consequence, the disk frequently
dislocates or slips from its position between
the vertebrae
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Specialized CT
Bone
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Bone
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Bone is a specialized connective tissue composed of
intercellular calcified material, the bone matrix, and
three cell types: osteocytes, which are found in cavities
(lacunae) within the matrix; osteoblasts, which
synthesize the organic components of the matrix; and
osteoclasts, which are multinucleated giant cells
involved in the resorption and remodeling of bone tissue
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Bone…
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