TissuesChapter 3.3

Connective Tissue

Connective Tissue• Found everywhere in

the body– Never exposed to the

outside environment• Includes the most

abundant and widely distributed tissues

• Functions– Binds body tissues

together– Supports the body– Provides protection– Transports materials

• Variations in blood supply– Some tissue types are

well vascularized– Some have poor blood

supply or are avascular

• Have receptors for– Pain, pressure,

temperature• Extracellular matrix

– Non-living material that surrounds living cells

Extracellular Matrix• Two main elements

– Ground substance – mostly water along with adhesion proteins and polysaccharide molecules

– Fibers• Produced by the cells• Three types

– Collagen fibers– Elastic fibers– Reticular fibers

• The combination of and the type of the two elements determines the connective tissue type– Connective tissue proper– Fluid connective tissue– Supporting connective tissue

Connective Tissue Proper• Many types of cells,

fibers and syrupy ground substance– Fibroblasts

• Large, star-shaped cell that produces fibers by secreting proteins into the matrix

– Macrophages• Function as defensive

cells, clearing foreign particles

– Mast cells• Begin body’s defense

actions after injury or infection

• Matrix– Ground substance

• Syrupy, clear, colorless– Fibers

• Collagen fibers - strong and flexible

• Elastic fibers - stretches, but returns to original length

• Reticular fibers - interwoven network

• Examples– Skin– Fatty tissue– Tendons and

ligaments

Types Connective Tissue Proper• Areolar connective

tissue– Most widely distributed

connective tissue– Soft, pliable tissue

(Cobweb-like)

Types Connective Tissue Proper• Areolar connective

tissue– Most widely distributed

connective tissue– Soft, pliable tissue

(Cobweb-like)– Contains all fiber types

• Can soak up excess fluid• Cusions and protects body

organs• Separates from and

attaches skin to muscles

• Adipose tissue– Matrix is an areolar

tissue • fat globules stored in

cytoplasm

– Many cells contain large lipid deposits

Types Connective Tissue Proper

• Adipose tissue– Matrix is an areolar

tissue • fat globules stored in

cytoplasm

– Many cells contain large lipid deposits

– Functions• Insulates the body• Protects some organs• Serves as a site of

fuel storage

Types Connective Tissue Proper

Types Connective Tissue Proper

• Dense connective tissue– Main matrix element

is collagen fibers closely packed

– Cells are fibroblasts

Types Connective Tissue Proper

• Dense connective tissue– Main matrix element

is collagen fibers closely packed

– Cells are fibroblasts– Examples

• Tendon – attach muscle to bone

• Ligaments – attach bone to bone

• Reticular connective tissue– Delicate network

of interwoven fibers

Types Connective Tissue Proper

• Reticular connective tissue– Delicate network

of interwoven fibers

– Forms stroma (internal supporting network) of lymphoid organs

• Lymph nodes• Spleen and liver• Bone marrow

Types Connective Tissue Proper

Fluid Connective Tissue

• Blood– Blood cells (red,

white, platelets) surrounded by fluid matrix (blood plasma)

– Fibers are visible during clotting

Figure 3.19h

Fluid Connective Tissue

• Blood– Blood cells (red,

white, platelets) surrounded by fluid matrix (blood plasma)

– Fibers are visible during clotting

– Functions as the transport vehicle for materials

Figure 3.19h

Type Supportive Connective Tissue

• Bone (osseous tissue)– Hardest of

connective tissues– Functions

• Used to protect and support the body

• Forms “levers” for movement

• Forms red blood cells

• Stores calcium and phosphorus

Type Supportive Connective Tissue

• Bone (osseous tissue)– Hardest of

connective tissues– Functions

• Used to protect and support the body

• Forms “levers” for movement

• Forms red blood cells

• Stores calcium and phosphorus

– Composed of:• Bone cells (osteocytes) in

lacunae (cavities)• Hard matrix of calcium

phosphate salts• Large numbers of collagen

fibers

• Hyaline cartilage– Most common

cartilage• Found on ends of

bones in joints• Soft part of nose• Supporting rings in

respiratory passages• Entire fetal skeleton

Type Supportive Connective Tissue

• Hyaline cartilage– Most common

cartilage• Found on ends of

bones in joints• Soft part of nose• Supporting rings in

respiratory passages• Entire fetal skeleton

– Composed of:• Abundant, very fine

collagen fibers• Rubbery matrix

Type Supportive Connective Tissue

• Elastic cartilage– Dense network of

elastic fibers– More flexible than

hyaline cartilage

Type Supportive Connective Tissue

• Elastic cartilage– Dense network of

elastic fibers– More flexible than

hyaline cartilage– Provides elasticity and

support– Found

• External ear• Epiglottis• Parts of larynx

Type Supportive Connective Tissue

• Fibrocartilage– Highly compressible

and very tough– Examples

• Cushion-like discs between vertebrae

• Cushions bones in knees and pelvic girdle

Type Supportive Connective Tissue