Connective Tissues


A. Characteristics
1) Cells are separated by large amounts of extra-cellular substance or matrix
2) Cells interspersed in matrix of Connnective Tissue
3) Matrix
        a. holds and surrounds specialized cells
        b. produced by the cells
        c. can be fluid, gel-like or solid
4) scattered in the matrix are thread-like microscopic fibers
    a. collagen:
            strong and wavy.
            Thus, tissues with collagen fibers are flexible and strong
            e.g. ligaments (joins bones)
    b. reticular:
            Means “net”
            Fine, branching fibers made mostly of collagen
            Thus, these fibers form a “framework” that supports many organs.  Also made of collagen.
    c. elastic:
            Made mostly of elastin (a stretchy protein)
            Stretch and easily snap back into shape.
            Thus, tissues with lots of these fibers can expand and then return to their original shape.

B. General Functions of Connective Tissues
1) To join together the other tissues of the body (tendons and ligaments)
2) Support (trachea, bones)
3) Protect underlying organs (skull)
4) Transport (blood)
5) Nutritive Functions (blood)
6) Immune Function (lymphocytes/white blood cells)
7) Storage sites & insulation (Fat tissue)

C. Types of Connective Tissue
  1) Connective tissue (Loose & Dense)
  2) Cartilage
  3) Bone tissue
  4) Blood
  5) Lymph (not discussed)

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Dense Regular Connective Tissue
Dense White Fibrous CT
Connective Tissue
Lots of collagen fibers, all running in the same direction lending it strength
Function:
    Connects structures that need a strong bond
Found
     tendons
     ligaments
     organ capsules
     dermis

Photo taken by Dr. S. Desai

This is a photo of a tendon.  Notice the large number of collagen fibers.

    Areolar CT                     Elastic cartilage        Compact bone
    Adipose CT                    Hyaline cartilage       Blood
    Reticular CT                   Fibrocartilage
    Elastic CT
    Dense white fibrous CT

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Adipose Tissue
Connective Tissue
Looks like chicken wire
Functions:
    Energy storage
    Insulation
    Shock absorber
    Communication (gender)
Found
     under skin (hypodermis)
     around organs
     breast
     cavities within bone

Photo taken by Dr. S. Desai

Low power                                                                       High power
Looks like chicken wire.

    Areolar CT                     Elastic cartilage        Compact bone
    Adipose CT                    Hyaline cartilage       Blood
    Reticular CT                   Fibrocartilage
    Elastic CT
    Dense white fibrous CT
 

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Areolar Connective Tissue
Connective Tissue
Looks like fiberglass
Functions:
    Loose packing
    Support
    Nourishment
Found
    packing between glands, muscles, and nerves
    attaches the dermis and epidermis to underlying tissues
    basement membrane (arteries and veins)

Photo taken by Dr. S. Desai

Low power (100x)                                              High power (400x)
Looks like fiberglass

    Areolar CT                     Elastic cartilage        Compact bone
    Adipose CT                    Hyaline cartilage       Blood
    Reticular CT                   Fibrocartilage
    Elastic CT
    Dense white fibrous CT
 

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Reticular Connective Tissue
Connective tissue
Lots of branching collagen fibers  very thin and netted
Function:
    Fills the inside of many organs
    Acts as a filter in spleen and lymph nodes
Found
     cavities in
      liver
      spleen
      lymph nodes
      basement membrane

We do not have a slide of reticular CT

    Areolar CT                     Elastic cartilage        Compact bone
    Adipose CT                    Hyaline cartilage       Blood
    Reticular CT                   Fibrocartilage
    Elastic CT
    Dense white fibrous CT
 

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Elastic Connective Tissue
Connective Tissue
Lots of elastic fibers look squiggly
Function:
    Allows stretching of organs
Found
     lungs
     around elastic arteries
     vocal cords

We do not have a slide of Elastic CT

    Areolar CT                     Elastic cartilage        Compact bone
    Adipose CT                    Hyaline cartilage       Blood
    Reticular CT                   Fibrocartilage
    Elastic CT
    Dense white fibrous CT
 

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Cartilage (Type of Connective Tissue)
a. Functions
  i. support for soft tissues
  ii. forms a sliding area for joints so bones can move easily
b. Chondrocytes
  “cartilage cells”
        i. secrete a tough extra-cellular substance consisting of fibers
c. Matrix is a firm gel
        i. lacunae:  cavities in the matrix where the cells live
       ii. Lacks lymph & blood vessels & nerves
       iii. Chondrocytes are nourished by diffusion from capillaries
 

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Elastic Cartilage
Connective Tissue
Lots of elastic fibers
Lends support but lots of flexibility
Looks like hyaline cartilage, but has more elastic fibers;  Some students say it looks like Starry Night by Van Gogh
Found
     ear
     auditory tube
     epiglottis

Photo taken by Dr. S. Desai

The elastic fibers in this slide preparation are much darker than the ones you will see in lab.  However, this tissue will still the visible elastic fibers lacking in hyaline cartilage.  In addition, there will only be one chondrocyte per lacuna.

    Areolar CT                     Elastic cartilage        Compact bone
    Adipose CT                    Hyaline cartilage       Blood
    Reticular CT                   Fibrocartilage
    Elastic CT
    Dense white fibrous CT
 

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Hyaline Cartilage
Connective tissue
“glass” because clear in living tissue; Two chondrocytes per lacuna
Functions:
    Support with flexibility
    Forms smooth surfaces in joints
Found
     “C”-shaped rings in trachea
     nasal cartilage
     ends of long bones
     connects ribs to sternum

Photo taken by Theresa Carrera

Photo of hyaline cartilage in the trachea. 1000x

    Areolar CT                     Elastic cartilage        Compact bone
    Adipose CT                    Hyaline cartilage       Blood
    Reticular CT                   Fibrocartilage
    Elastic CT
    Dense white fibrous CT
 

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Fibrocartilage
Connective Tissue
More collagen fibers arranged in bundles than hyaline cart.
Function:
    Shock absorbers
Found
     between intervertebral disks
     pubis symphysis
     knee joint

We do not have a slide of this tissue

    Areolar CT                     Elastic cartilage        Compact bone
    Adipose CT                    Hyaline cartilage       Blood
    Reticular CT                   Fibrocartilage
    Elastic CT
    Dense white fibrous CT
 

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Bone (Type of Connective Tissue)
A. Functions
1.supports the mature skeleton
2. protects internal organs
3. storage reservoir for Ca and P
  -osteoblasts (“bone” “germ/bud”)
   cells that produce bone
  -osteoclasts: cells that breakdown bone
  -always being modified
 

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Compact Bone
Connective Tissue
Looks like tree rings
Functions:
    Support
    Protection
Found
     Outer layer of bones

Photo taken by Dr. S. Desai

Each osteon looks looks like tree rings.  The large holes in the center of each osteon ("tree") is a central canal.  The "ants" are the lacuna (the holes that house the osteocytes) and the "legs of the ants" are canaliculi (singular canaliculus; that allow the osteocytes to touch each other).

    Areolar CT                     Elastic cartilage        Compact bone
    Adipose CT                    Hyaline cartilage       Blood
    Reticular CT                   Fibrocartilage
    Elastic CT
    Dense white fibrous CT

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Blood
Connective Tissue
Fluid matrix
Function:
    Transport
    Thermoregulation
    Defense against pathogens
    Communication

Photo taken by Dr. S. Desai

The red arrows indicate red blood cells, the green arrow indicates a white blood cell, the pink arrows indicate platelets.

    Areolar CT                     Elastic cartilage        Compact bone
    Adipose CT                    Hyaline cartilage       Blood
    Reticular CT                   Fibrocartilage
    Elastic CT
    Dense white fibrous CT
 

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Designed and constructed by
M. E. Janowski-Bell, Ph.D.
Assistant Professor of Biology
Victoria College
tarantula@victoriacollege.edu