Connective Tissue
Connective Tissue
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Binds together, supports and strengthens other
body tissues
Protects and insulates internal organs
Compartmentalizes structures such as skeletal
muscle
The major transport system within the body
Site of stored energy reserves
Main site of immune responses
General Features of Connective
Tissue
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2 basic parts:
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Cells and Matrix
Matrix – material between widely spaced cells
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Consists of protein fibers and ground substance
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Ground substance – material between cells and fibers
secreted by the cells and determine the tissue qualities
General Features of Connective
Tissue
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Does not occur on free surfaces
Has a nerve supply (except cartilage)
Highly Vascular (except cartilage and tendons)
Connective Tissue Cells
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Fibroblasts – large flat cells with branching
processes. Migrate throughout connective tissue
secreting the fibers and ground substance
Macrophages – develop from white blood cells.
Surround and engulf material by phagocytosis
Mast Cells – alongside blood vessels that supply
connective tissue. Produce histamine – a
chemical that dilates blood vessels.
Adipocytes – “fat cells” store triglycerides.
Connective Tissue Matrix – Ground
Substance
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Ground Substance – component of a
connective tissue between the cells and fibers,
supports cells, binds them together, and
provides a medium through which substances
are exchanged.
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Ex. Hyaluronic Acid
Connective Tissue Matrix – Fibers
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Strengthens and supports connective tissue
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Collagen Fibers
Strong, resist pulling forces, flexible
 Made of the protein collagen which is the most abundant
protein in your body
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Elastic Fibers
smaller in diameter than collagen fibers, branch to form
network
 Made of the protein elastin
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Reticular Fibers
Provide support for the walls of blood vessels
 Made of collagen with a glycoprotein covering
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Marfan Syndrome
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An inherited disorder caused by a defective gene
for the glycoprotein fibrillin resulting in
abnormal development of elastic fibers. This
causes tissues that contain many elastic fibers to
be malformed or weak (including the covering
of bone, ligament that suspends the lens of the
eye, and the walls of large arteries
People with Marfan syndrome are often tall,
have long arms, legs, fingers and toes, blurred
vision, and weakened aortic walls that may burst.
Types of Connective Tissue
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There are 6 types of connective tissue that vary
by the fibers, ground substance and cells
contained in it. Each type has a very specific
structure and function.
Loose Connective Tissue
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Fibers are loosely intertwined among many cells.
3 types of loose connective tissue
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Areolar Connective Tissue – one of the most widely
distributed connective tissues in the body.
Contains fibroblasts, macrophages, plasma cells, mast
cells, adipocytes and a few white blood cells as well as all 3
types of fibers
 Helps to form the subcutaneous layer
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Loose Connective Tissue
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Adipose Tissue – The cells, called adipocytes, are
specialized for storage of triglycerides. Adipocytes
fill up with a large fat droplet so the nucleus gets
pushed to one side of the cell.
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Used for insulation, protection and as an energy reserve
Reticular Connective Tissue – made of interlacing
reticular fibers and reticular cells that connect to
each other to form a network.
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Used to bind together smooth muscle cells and to filter
out worn out blood cells and bacteria
Dense Connective Tissue
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Contains more numerous, thicker and denser
fibers but fewer cells than loose connective
tissue.
3 types:
Dense regular connective tissue
 Dense Irregular connective tissue
 Elastic Connective Tissue
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Dense Regular Connective Tissue
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Bundles of collagen fibers are arranged regularly
in parallel patterns that give it strength.
Withstands pulling from the ends, but unravels
when pulled from the side
Silvery white in appearance. Tough and pliable
Found in tendons and ligaments
Dense Irregular Connective
Tissue
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Collagen fibers are packed closely together in an
irregular, random pattern
Found in parts of the body where pulling forces
are exerted in various directions
Usually found in sheets
Examples: Dermis of the skin, heart valves,
perichondrium and periosteum
Elastic Connective Tissue
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Contains branching elastic fibers and fibroblasts
Yellowish in color
Strong, can regain shape after stretching
Found in lungs and arteries
Cartilage
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Dense network of collagen fibers and elastic
fibers embedded in chondroitin sulfate (a
rubbery component of the ground substance)
Can withstand more stress than the dense and
loose connective tissue.
Collagen fibers make the tissue strong,
chondroitin sulfate makes it resilient
Cartilage - continued
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Chondrocytes – mature cartilage cells
Lacunae – holes in the matrix in which the cells
sit
Perichondrium – dense irregular connective
tissue that surrounds cartilage
3 types – hyaline, fibrocartilage and elastic
Cartilage is AVASCULAR and NO nerve supply
(but the perichondrium does)
Hyaline Cartilage
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Gel like ground substance, collagen fibers (not
visible with normal stains) and prominent
chondrocytes
Most abundant cartilage in the body
Found at the end of long bones to cushion
joints and at epiphyseal plates (growth plates in
bones)
Weakest of the 3 types of cartilage
Fibrocartilage
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Chondrocytes scattered among visible bundles
of collagen fibers
No perichondrium
Strongest of the 3 types of cartilage
Found in the intervertebral discs
Elastic Cartilage
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Chondrocytes located in a threadlike network of
elastic fibers
Provides strength, elasticity and maintains the
shape of certain structures (like the external ear)
Bone Tissue (osseous tissue)
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2 types – compact and spongy
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Compact
Osteon – basic unit of compact bone
 Lamellae – concentric circles of matrix
 Lacunae – spaces in the matrix that house cells
 Osteocytes – mature bone cells
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Spongy
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Trabeculae – columns of bone with spaces filled with red
bone marrow
Micrograph of Spongy Bone
An electron micrograph scan of
spongy bone in an osteoporosis
patient. Osteoporosis occurs
when a body's blood calcium
level is low and calcium from
bones is dissolved into the blood
to maintain a proper balance.
Blood Tissue
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Connective Tissue with a liquid matrix
Red Blood Cells (erythrocytes) – transport
oxygen
White Blood Cells – function in immunity
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Neutrophils, Eosinophils, Basophils, T and B
leukocytes, natural killer cells and Monocytes
Platelets – participate in blood clotting