Connective Tissue
Functions mainly to bind and support other tissues
• Areolar Tissue is loose connective tissue that consists
of a meshwork of collagen, elastic tissue, and
reticular fibres - with many connective tissue cells in
between the meshwork of fibres.
• Found in dermis
• also found in or around mucous membranes, and
around blood vessels, nerves, and the organs of the
body.
Adipose Tissue loose fibrous connective tissue packed with many cells
(called "adipocytes") specialized for storage of triglycerides more
commonly referred to as "fats".
• Adipose tissue forms a thick layer under the skin,
around the kidneys and in the buttocks.
More generally, it is found at the same locations
throughout the body as areolar connective tissue.
• Specific examples of the locations of adipose tissue
include:
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o
o
o
o
o
Subcutaneous layer deep to skin
Around the heart
Around the kidneys
Yellow marrow of the long bones
Padding around the joints
Inside the eye-socket, posterior to the eyeball.
• White adipose tissue (WAT) or white fat is
one of the two types of adipose tissue found
in mammals.
• brown adipose tissue.
o Found in newborns and hibernating animals
• Connective tissues have
a sparse population of
cells scattered through
an extracellular matrix
• Matrix generally
consists of a web of
fibers.
o May be liquid, jellylike or solid
• In most cases, the
connective tissue cells
secrete the matrix
Connective Tissues
• Unlike epithelial tissues, connective tissues have
abundant matrix (intercellular material) and have a
good blood supply (expect cartilage)
• Fibroblast is common cell type
o Star shaped
o Secretes high amounts of protein
• Leukocytes are a type of white blood cell wonder
around connective tissues
• Macrophages function as scavenger cell and
defend against infection
macrophage
• Neutrophils
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o
o
o
Leukocytes
Most numerous (~60%)
Only occasionally found outside of blood
Anti-bacterial cells which lyse bacterial cells
Rapidly gather during inflammation
• Eosinophils
o 2-4%
o Associated with allergies and parasites
• Basophils
o >1%
o Seems to function similar to mast cells, involved in inflammation
• Monocytes
o largest WBC, 5%
o Same function as macrophages – engulf and digest
• Lymphocytes
o 30%
o Commonly found in connective tissues
o Respond to inflammation, mediating and regulating immune
responses
• Mast Cell located throughout connective tissues
adjacent to blood vessel
o Help release heparin and histamine
Proteins within the
connective tissues
• Three kinds of connective tissue fibers
o Collagenous fibers
• Made of collagen protein.
• Collagenous fibers are nonelastic and do NOT tear easily
o Elastic fibers
• Made of protein called elastin
o Long threads
o Elastin fibers provide a rubbery quality
o Reticular fibers
• Most thin highly branched
• Attached connective tissue to surrounding tissue
Collagenous fibers
Elastic fibers
Reticular fibers
loose connective, adipose tissue, fibrous
connective tissue, cartilage, bone and blood
Loose Connective Tissue
• Found throughout body
• Binds body parts together
• Such as skin and underlying
organs
• Majority are fibroblasts
o separated by gel-like
substance
o Containing collagenous
and elastic fibers
Loose connective tissue binds epithelia to
underlying tissues and functions as packing
materials, holding organs in place
• Fibroblasts – secrete protein ingredients of the
extracellular fibers
• Macrophages – WBC that roam the maze of fibers,
engulfing bacteria and debris of dead cells
Adipose Tissue
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•
•
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Specialized form of loose connective tissue
Adipose tissue pads and insulates the body
Stores fuel as fat molecules
Each cell swells when fat is stored and shrinks when
the body uses fate as fuel
Fibrous Connective Tissue
• Extremely dense due to large amounts of
collagenous fibers
• Organized into parallel bundles to maximize
strength
• Tendons
• Ligaments
Tendon
Cartilage
• Has an abundance of collagenous fibers
embedded in rubbery matrix
o Matrix is made of protein-carbohydrate complex
• Chondrocytes secrete collagen
• Collagenous fibers make cartilage strong yet
flexible
• Skeleton of shark is made of cartilage
• Animals are made of embryonic skeletons are
cartilaginous
• Flexible supports
• Pinna, vertebral disks
Cartilage
• Lacks a vascular system
• Heals slowly
• Cartilage cells (chondrocytes) lie within lacunae
in the gel like fluid matrix
Hyaline Cartilage
• Most common cartilage
• White in color
• Abundant fine collagen fibers
• Found at the end of the bone
• Supports respiratory system
Hyaline cartilage in the trachea
Elastic Cartilage
Stains a little darker
Made with elastic fibers
Provides framework for external ears & part of larynx
Fibrocartilage
Helps absorb shock
Found in intervertebral disks, knees and pelvis
Tough tissue with many collagenous fibers
Bone
• Extremely dense!
• Most rigid connective tissue
• Deposits of mineral salts and collagen within
the matrix
• Protein and salt ratio is just perfect
• Internal support of body
Protects
• Forms muscle attachments
• Cite for blood cell formation
• Stores fats
• Skeleton is made of bone, a mineralized
connective tissue
• Matrix of collagen (flexible) and minerals (hard)
o Calcium, magnesium, phosphate ions
bone
• Structure of bone - Repeating units called osteons
• Each osteon has a concentric layers of mineralized
matrix deposited around a central canal containing
blood vessels and nerves that service the bone
• Arranged into osteons or Haversian systems
o Store calcium salts
o Withdraw
• Lacking calcium in diet
• Create embryo
Blood
• Matrix called plasma
• Mainly water, salts and variety of
dissolved proteins
• Suspended in plasma are erythrocytes
(red blood cells), leukocytes (white
blood cells) and cell fragments called
platelets
o Red blood cells carry oxygen
o White cells function in defense against
viruses, bacteria and other invaders
o Platelets aid in blood clotting