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Connective Tissue (CT)

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Title: Connective Tissue (CT)


1
Connective Tissue (CT)
2
Connective Tissue
  • A really diverse group of tissues
  • Connective tissue (CT) is the most diverse of the
    four tissue types with a wide variety of
    functions. CT forms an extensive compartment in
    the body and can be considered as the "glue" that
    holds the body together.

3
Composition of Connective Tissue
  • Cells
  • Extracellular matrix
  • Ground substance
  • fibres

4
Cells of CT
  • Fibroblasts
  • the principal cells of connective tissue.
  • Matrix secreting cells
  • responsible for the secretion of all types of
    fibres (collagen, reticular, elastin) and the
    complex carbohydrates of ground substance.

5
Cells of CT
  • Chondroblasts chondrocytes
  • the matrix-secreting cells of cartilage.
  • Osteoblasts osteocytes
  • the matrix-secreting cells of bone.
  • Macrophages
  • are phagocytic cells derived from monocytes.

6
Cells of CT
  • Adipose cells
  • also called adipocytes, these cells are
    specialized to store lipids.
  • Mast cells
  • have granules containing histamine, heparin and
    anaphylactic factors.
  • when released in response to an antigen, they
    cause hypersensitivity reactions, allergy and
    anaphylaxis.
  • Lymphocytes
  • cells responsible for immune responses that
    circulate in the blood.
  • normally present in small numbers but their
    number increases dramatically at certain sites of
    tissue inflammation.
  • Plasma cells
  • are derived from B-lymphocytes and produce
    antibodies against a specific antigen.

7
Cells of CT
  • Neutrophils
  • are white blood cells that act as phagocytes in
    the early stages of acute inflammation.
  • Eosinophils
  • are white blood cells that are found at sites of
    allergic reaction and parasitic infection.
  • Basophils
  • are white blood cells that are similar to mast
    cells in having vasoactive agents released in
    response to an allergen.
  • Monocytes
  • are white blood cells that will give rise to all
    the phagocytes namely macrophages

8
Ground substance
  • occupies the space between the cells and fibres
    of connective tissues.
  • high water content
  • consists largely of proteoglycans and hyaluronic
    acid.

9
Fibres
  • There are three types of fibres secreted by
    connective tissue cells collagen
    fibres, reticular fibres, and elastic fibres. The
    abundance and preponderance of different types of
    fibres varies in different CTs.

10
Collagen fibres
  • the most common fibre type
  • flexible fibres with a high tensile strength.
  • Type I collagen is the most prevalent type of
    collagen (90) - found in the dermis of the skin,
    bone, tendon, organ capsules and many other
    areas.
  • Type II collagen found in cartilage are finer
  • Type IV collagen is found in the basement
    membrane of epithelia.

11
Reticular fibres
  • closely related to collagen fibres.
  • They are made of type III collagen fibers
  • given their name because they are arranged in a
    mesh-like pattern.
  • provide a supporting framework for the cellular
    constituents of various tissues and organs
  • most are produced by fibroblasts.

12
Elastic fibres
  • thinner than collagen fibres
  • they give tissue the ability to cope with stretch
    and distension.
  • they are interwoven with collagen fibres in order
    to limit excessive stretching and tearing.
  • found in certain ligaments (elastic ligaments),
    some cartilage (elastic cartilage) and in large
    arteries (elastic arteries).
  • most are produced by fibroblasts.

13
Classification of connective tissues
  • Connective tissues are classified on the basis of
    types and relative abundance of cells, fibres and
    ground substance, and on the organization of
    fibres. The images below will introduce you to
    the diversity of connective tissues.

14
Loose (or areolar) connective tissue
  • abundant ground substance and thin and relatively
    sparse fibres.
  • located beneath epithelia that line the internal
    surfaces of the body, glands and small vessels.

15
Loose (or areolar) connective tissue
16
Dense irregular connective tissue
  • collagenous fibres make up the bulk of the tissue
    (give it strength)
  • fibroblasts are scarce and usually the only cell
    type present.
  • little ground substance is present.
  • the fibres are typically arranged in bundles in
    various directions (hence irregular), which
    enables the tissue to withstand various stresses.
  • found on the outside of many organs and in the
    dermis of the skin, meninges surrounding the
    spinal cord

17
Dense irregular connective tissue
18
Dense regular connective tissue
  • collagenous fibres are packed in dense regular
    arrays, between which lie rows of cells
    (fibroblasts).
  • found in tendons (which connect muscles to bones)
    and ligaments (which connect bones to bones,

19
Dense regular connective tissue
20
Adipose tissue
  • adipocytes, which are specialized to store fat,
    are found throughout loose connective tissue.
  • Fat cells appear as empty circles in which a
    peripheral nucleus can often be identified

21
Adipose tissue
22
Cartilage
  • tissue whose cells, called chondrocytes, secrete
    a very specialized matrix. specifically
    hyaluronic acid, chondroitin sulfate and keratan
    sulfate.
  • Collagen (type II) fibrils are also present in
    the matrix
  • the chondrocytes sit in spaces called lacunae,
    which they fill during life.

23
Hyaline Cartilage
Mostly collagen fibres found at the ends of ribs
in the larynx, trachea, and bronchi and on the
articular surface of bones.
24
Elastic Cartilage
  • found in the external ear, epiglottis, eustachean
    tube and larynx.

25
Fibrocartilage
  • consists of chondrocytes in combination with
    dense connective tissue
  • found are the intervertebral disks, the symphysis
    pubis, and certain
  • places where tendons attach to bone.

26
Bone
  • characterized by a mineralized extracellular
    matrix.
  • the matrix is secreted by cells called
    osteocytes.
  • consists of mostly of mineralized collagen fibres
    arranged in lamellae.

27
Compact Bone
  • Also known as dense or cortical bone
  • consists of numerous units called osteons or
    Haversian systems which consists of a central
    Haversian canal which contains its vascular and
    nerve supply around which lamellae of collagen
    fibres are concentrically arrayed. Osteocytes lie
    in lacunae between the lamellae and make contact
    with other osteocytes, and ultimately the
    Haversian canal, via cell processes which they
    extend in little channels or canaliculi.
  • Found in the long axis and diaphysis of the long
    bones

28
Anatomy of a Bone
29
Compact Bone
30
Compact Bone
31
Spongy Bone
  • Also known as trabecular and cancellous bone
  • the collagen is contained within the irregularly
    shaped trabeculae. The spaces between the
    trabeculae are filled with bone marrow which is
    actively involved in red blood cell formation.
  • Found in the margins of the bone marrow cavity,
    ends of bones (epiphyses)

32
Spongy Bone
33
Hemopoietic tissue
  • The only hemopoietic tissue in the adult is red
    bone marrow. Red bone marrow gives rise to red
    blood cells, granulocytes (neutrophils,
    eosinophils and basophils), monocytes and
    platelets. Lymphocytes are formed both in the red
    bone marrow and in lymphatic tissue.

34
Blood
  • fluid connective tissue that circulates throught
    the body.
  • functions in bringing nutrients and oxygen to
    tissues, removing waste products, transporting
    hormones and with the immune response.

35
Figure 12 illustrates a blood smear (RBC,
neutrophil and basophil)
36
Figure 13 illustrates a blood smear (eosinophil,
RBC, platelets)
37
Figure 14 illustrates a blood smear (lymphocyte,
eosinophil, RBC)
38
Figure 15 illustrates a blood smear (monocyte,
neutrophil and lymphocyte, platelets)
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