CONNECTIVE TISSUE

Connective Tissue

• Functions to bind, support, insulate and protect parts of the body.

• 3 Components: Specialized cells, ground substance and protein fibers.– Ground substance is non-cellular material

that separates cells.• Can be solid to fluid in consistency.

3 Types of Protein Fibers Found in Connective Tissue

1. Collagen Fibers: Contain collagen; flexible and strong.

2. Reticular Fibers: Thin collagen fibers; highly branched to form support networks

3. Elastic Fibers: Contain elastin; very elastic

• The ground substance plus the protein fibers make up the MATRIX of the tissue.

Fibrous Connective Tissue

3 Main Types of Connective Tissue

A. Fibrous

B. Supportive

C. Fluid

A. Fibrous Connective Tissue

Two types: • Dense fibrous tissue• Loose fibrous tissue

• Both types contain FIBROBLASTS: Cell that produces fibers and other substances.

Loose Fibrous Connective Tissue

• ie. Areolar tissue• Supports epithelium and internal organs.

– Allows expansion of lungs, arteries and bladder.

– Forms a protective covering around many internal organs.

Adipose Tissue

• Specialized cells that enlarge to store fat.– Male (12%; belly)– Females (18- 28%; abdomen, hips, thighs)

• Tightly packed; little or no extracellular matrix.

• Used for energy, insulation and organ protection.

• Found beneath the skin, around the kidneys and on the surface of the heart.

• Regenerate quickly.

Chicken Wire!

Dense Fibrous Connective Tissue

• Made of many tightly-packed collagen fibers.• Very specific functions, for example:

– Found in tendons (connect muscle to bone).

– Found in ligaments (connect bones to other bones at joints).

Dense regular connective tissue,

transverse, tendon

Dense regular connective tissue, longitudinal, tendon

B. Supportive Connective Tissue

Two types:• Cartilage• Bone

• Solid extracellular matrix.– Made by chondroblasts and chondrocytes

in cartilage.– Made by osteoblasts and osteocytes in

bone.

Supportive Connective Tissue: Cartilage

• Cells lie in small chambers called LACUNAE.• Matrix is solid, but flexible.• Heals slowly due to lack of blood flow.

3 Types of Cartilage (based on fibers):• Hyaline cartilage• Elastic cartilage• Fibrocartilage

Hyaline Cartilage

• Most common.• Contains only fine collagen fibers.• Glassy, translucent matrix.

• Found in the nose, at the ends of long bones, ribs, and is the composition of the fetal skeleton.

Elastic Cartilage

• Made of more elastic fibers than hyaline cartilage.– More flexible!

• Found in the outer ear.

Fibrocartilage

• Matrix of strong collagen fibers.• Can withstand tension and pressure.

• Found in the disks between the vertebrae of the backbone, knee joint

Supportive Connective Tissue:Bone

• Extremely rigid matrix; made of calcium salts formed around collagen fibers.

Two types of bone:• Compact Bone

– Found in shafts of long bone.• Spongy Bone

– Found on ends of long bone.

Compact Bone Composition

• Bone matrix is deposited in thin layers, LAMELLAE, forming concentric circles.

• Lamella form around tiny longitudinal tubes called OSTEONIC CANALS.

• Bone cells, OSTEOCYTES, are found in the lacunae between the lamellae.

• Osteocytes and intercellular material layered around the osteonic canal form a unit called OSTEONS.

Compact Bone Composition

• Each osteonic canal carries a blood vessel for nutrient supply.

• Thin extensions, CANALICULI, connect bone cells to other bone cells. – Materials move quickly from blood vessels

to bone cells; HEAL QUICKLY!

Spongy Bone

• Open, bony latticework with bony bars and plates separated by irregular spaces.

• Lighter than compact bone.

• Found at ends of long bone; surrounds the bone marrow cavity.

Bone and Cartilage in the Knee

Fluid Connective Tissue:Blood

• Fluid matrix of cellular elements and plasma.• Three cellular elements:

1. ERTHRYOCYTES (Red blood cells): Carry oxygen.

2. LEUKOCYTES (White blood cells): Fight infection.

3. PLATELETS: Pieces of cells that clot blood.

• Located in blood vessels.

Blood Functions

• Transports nutrients and oxygen to tissue fluid for cell benefits.– Tissue fluid bathes cells in nutrients,

removes CO2 and wastes.• Distributes heat; factors into fluid, ion and

pH balance.

Fluid Connective Tissue:Lymph

• Clear to faintly yellow, watery fluid derived from tissue fluid.

• Contains white blood cells.