Pages 93-97

Connective TissueThe most abundant type of tissue!

Collagen is a major protein found in connective tissueAlso the most common protein found in the body

Functions:Provides protectionBinds body tissues togetherSupports the body

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Vascularity – blood supplyVariations in blood supply

Some are well vascularizedSome have a poor blood supply or are

avascular; Examples include: tendons, ligaments

As a result, these take longer to heal

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The Extracellular Matrix (ECM)a unique and distinguishing characteristic

of connective tissue

Nonliving material that surrounds living cellsGelatinous-like materialSecreted by the connective tissue cells

Composed of two main components:Ground SubstanceFibers

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Ground Substance Secreted by connective tissue

cells Similar to cytosol in composition and

function

Composed of: mostly water adhesion proteins polysaccharides

FibersSecreted by connective tissue cells

Three types:1.Collagen (white) fibers

Allow CT to withstand pulling/tension

2.Elastic (yellow) fibers Contain elastin- allows stretching

3.Reticular fibers (a type of collagen) Short fibers that create a mesh-like network

Connective Tissue TypesFrom most rigid to softest, (or most fluid):

BoneCartilageDense connective tissueLoose connective tissueBlood

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BONEKnown as osseous tissueProduced by Osteocytes (bone cells)A Hard matrix of calcium saltsFunctions to protect and support the body

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Figure 3.19a Connective tissues and their common body locations.

Bone cellsin lacunae

Centralcanal

Lacunae

Lamella

(a) Diagram: Bone Photomicrograph: Cross-sectionalview of ground bone (165×)

BONE

CARTILAGEmore flexible than bone

Found in only a few places in the bodyProduced by Chondrocytes (cartilage cell)Three types of cartilage:

Hyaline (most abundant; larynx, intercostal, bone ends)

Elastic (external ear and epiglottis)Fibrocartilage (intervertebral discs; pubic

symphysis)

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Figure 3.19b Connective tissues and their common body locations.

Chondrocyte(cartilage cell)

Chondrocytein lacuna

Matrix

Lacunae

Photomicrograph: Hyaline cartilagefrom the trachea (400×)

(b) Diagram: Hyalinecartilage

HYALINE CARTILAGE

Figure 3.19c Connective tissues and their common body locations.

Chondro-cytes inlacunae

Collagenfibers

Chondrocytesin lacunae

Collagen fiber

Photomicrograph: Fibrocartilage of anintervertebral disc (150×)

(c) Diagram: Fibrocartilage

FIBROCARTILAGE

DENSE CONNECTIVE TISSUEStrong, ropelike structuresMain matrix element is collagen fiber made

by fibroblastsLocations:

Tendons—attach skeletal muscle to bone Ligaments—attach bone to bone at Dermis—lower layer of the skin

Found where strength of interconnection is required

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Figure 3.19d Connective tissues and their common body locations.

Ligament

(d) Diagram: Densefibrous

Photomicrograph: Dense fibrousconnective tissue from a tendon (475×)

Collagenfibers

Nuclei offibroblasts

Nuclei offibroblasts

Collagenfibers

Tendon

DENSE CONNECTIVE TISSUE: Ligament And Tendon

LOOSE CONNECTIVE TISSUEsofter tissues; less fibrousprovide cushioning, reduce friction, allow

stretchingThree types:

Areolar: wraps and secures organs Lamina propria: areolar layer that underlies all

mucous membranesAdipose: fat cells; energy storage; insulationReticular: provides structural framework for

organs/glands

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Figure 3.19e Connective tissues and their common body locations.

Mucosaepithelium

Laminapropria

Fibers ofmatrix

Nuclei offibroblasts

Elasticfibers

CollagenfibersFibroblastnuclei

(e) Diagram: Areolar Photomicrograph: Areolar connective tissue,a soft packaging tissue of the body (270×)

AREOLAR CONNECTIVE TISSUE

Figure 3.19f Connective tissues and their common body locations.

Nuclei offat cells

Vacuolecontainingfat droplet

Vacuolecontainingfat droplet

Nuclei offat cells

(f) Diagram: Adipose Photomicrograph: Adipose tissue from thesubcutaneous layer beneath the skin (570×)

ADIPOSE TISSUE

Figure 3.19g Connective tissues and their common body locations.

Spleen

(g) Diagram: Reticular Photomicrograph: Dark-staining networkof reticular connective tissue (400×)

ReticularcellBloodcellReticularfibers

White blood cell(lymphocyte)

Reticular fibers

RETICULAR CONNECTIVE TISSUE

BLOODBlood cells = red and white

surrounded by fluid matrix known as blood plasma

Soluble fibers are visible only during clottingFunction: transport vehicle for the CV system;

delivers: Nutrients Wastes Respiratory gases (oxygen and carbon dioxide)

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Figure 3.19h Connective tissues and their common body locations.

Photomicrograph: Smear of humanblood (1290×)

(h) Diagram: Blood

Blood cellsin capillary

Whiteblood cell

Redblood cells

Neutrophil (white bloodcell)

Red bloodcells

Monocyte(white bloodcell)

BLOOD