Lecture on Connective Tissues

Overview of Connective Tissues

• Connective tissues are diverse in structure and function.
• Key types include loose connective tissue, dense connective tissue, cartilage, bone, and blood.

Loose Connective Tissues

• Characteristics: Visible cells, loosely intertwined fibers.

Areolar Tissue

• Contains collagen fiber bundles (pink lines) and elastic fibers (thin pencil lines).
• Functions as a "background" texture with elastic fibers popping forward.
• Possible exam questions:
  • Identify fibers and cells.
  • Function and location questions based on textbook information.

Adipose Tissue

• Known for fat storage; cells are called adipocytes.
• Adipocytes are large, circular cells with a fat droplet.
• Functions include storage and cushioning of organs.
• Exam focus on identifying tissues, cells, and stored substances.

Reticular Tissue

• Contains numerous cells with reticular fibers (short, wavy cracks).
• Found in lymph nodes, spleen, liver, and red bone marrow.
• Supports blood production.

Dense Connective Tissues

• Characteristics: Tightly packed fibers, fewer visible cells.

Dense Regular Tissue

• Collagen fibers run in a regular, parallel pattern.
• Strong in the fiber direction but weak from other directions.
• Found in tendons and ligaments.

Dense Irregular Tissue

• Fibers run in multiple directions, providing strength in all directions.
• Found in the dermis of the skin, sclera, periosteum, and perichondrium.

Elastic Connective Tissue

• Contains both elastic and collagen fibers.
• Found in areas requiring stretching and recoiling, such as blood vessels.
• Resembles lasagna or turkey bacon in stained images.

Cartilage

• Characteristics: Avascular, lacks nerves, may line structures.

Hyaline Cartilage

• Most abundant but weakest cartilage.
• Found in the nose, ends of bones (articular cartilage).
• Lacunae with chondrocytes; has a perichondrium.

Elastic Cartilage

• Contains visible elastic fibers.
• Found in the ear (auricle/pinna); has a perichondrium.

Fibrocartilage

• Strongest cartilage with extensive collagen fibers.
• No perichondrium; found in meniscus, intervertebral discs, and pubic symphysis.

Bone

• Types: Compact and spongy.

Compact Bone

• Composed of osteons with central canals (Haversian canals), lamellae, lacunae with osteocytes, and canaliculi.
• Strong and supports body structure.

Spongy Bone

• Made of trabeculae, lacks osteons, porous and filled with red bone marrow.
• Supports hematopoiesis (blood formation).

Blood

• The only liquid connective tissue.
• Composed of:
  • Plasma (ground substance).
  • Erythrocytes (red blood cells) for oxygen transport, enucleated.
  • Leukocytes (white blood cells) with nuclei for immune response.
  • Thrombocytes (platelets) for clotting.

Exam Focus

• Identify tissues, fibers, and functions.
• Understand locations and properties of different tissues.
• Familiarize with unique characteristics such as avascularity in cartilage and compact bone structure.