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,
longitudinal, tendon
Dense regular
connective tissue,
transverse, 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.