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 networks3. 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. FibrousB. SupportiveC. 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.