Tissue: Connective Tissue

Connective Tissues• Composed of cells & extracellular matrix• Extracellular Matrix : fibers & ground substance)

secreted by cells• Cells rarely touch due to usually large amount of

intercellular material (extracellular matrix)• Consistency varies from liquid or gel to solid• Function is to support, connect, protect and insulate• Good nerve & blood supply except cartilage &

tendons

Types of Connective Tissue Fibers• Collagen (25% of protein in your body)

– tough, resistant to pull, yet pliable – formed from the protein collagen

• Elastin (lungs, blood vessels, ear cartilage)– smaller diameter fibers formed from protein elastin

surrounded by glycoprotein (fibrillin)– can stretch up to 150% of relaxed length and return to

original shape• Reticular (spleen and lymph nodes)

– thin, branched fibers that form framework of organs – formed from protein collagen

Connective Tissue

Found throughout the body; most abundant and widely distributed of the primary tissues.

4 main classes:– Connective tissue proper– Cartilage– Bone– Blood

Cell Type Representative Product or Activity Representativ

e Function

Fibroblast,

chondroblast,

osteoblast,

odontoblast

Production of fibers and ground substance Structural

Plasma cell Production of antibodies Immunologic

(defense)

Lymphocyte

(several types)

Production of immunocompetent cells Immunologic

(defense)

Eosinophilic

leukocyte

Participation in allergic and vasoactive reactions,

modulation of mast cell activities and the

inflammatory process

Immunologic

(defense)

Neutrophilic

leukocyte

Phagocytosis of foreign substances, bacteria Defense

Macrophage Secretion of cytokines and other molecules,

phagocytosis of foreign substances and bacteria,

antigen processing and presentation to other cells

Defense

Mast cell and

basophilic

leukocyte

Liberation of pharmacologically active molecules

(eg, histamine)

Defense

(participate in

allergic

reactions)

Adipocyte Storage of neutral fats Energy

reservoir, heat

production

Connective Tissue Proper: Dense Regular

Fig. 4.7b

Areolar Connective Tissue: Model

Figure 4.8

Connective Tissue Proper: Loose

Connective Tissue Proper: Loose

Reticular Tissue

Connective Tissue: Bone (Osseous Tissue)

Compact Bone

• Osteon = lamellae (rings) of mineralized matrix– calcium & phosphate---give it its hardness – interwoven collagen fibers (and other proteins) provide strength

and flexibility• Osteocytes in spaces (lacunae) in between lamellae• Canaliculi (tiny canals) connect cell to cell

– Central canal contains blood vessels, nerves & a lymphatic vessel

Structure of Long Bone

Microscopic Structure of Bone: Compact Bone

Bone Model

Fig. 6.10a

Fig. 5.23

Fig. 5.23a

Fig. 5.23b

Spongy Bone (Cancellous Bone)Osteocyte in lacuna

Spongy Bone (Cancellous Bone)1. Trabecula 2. Marrow

cavity 3. Adipose

(fat) cell 4.

Hemopoietic cells

5. Osteocyte in lacuna

Connective Tissue: Hyaline Cartilage

Figure 4.9f

Fig. 4.7h

Hundreds of Eyes Staring Back at YOU!

Connective Tissue: Blood