cartilage

Four Tissue Types

  • Epithelial
  • Connective
  • Muscle
  • Nervous

Connective Tissues

Types of Connective Tissues

  • Areolar
  • Loose
  • Adipose
  • Reticular
  • Dense Connective Tissue
    • Regular
    • Irregular
    • Elastic
  • Cartilage
    • Hyaline
    • Elastic
    • Fibrocartilage
  • Bone
  • Blood

Cartilage

  • Matrix secreted by chondroblasts (during growth) and chondrocytes (in adults).
  • Contains:
    • 80% water
    • Packed collagen fibers
    • Sugar proteins (chondroitin and hyaluronic acid)
  • Properties:
    • Tough yet flexible
    • Lacks nerve fibers (avascular)
    • Nutrient supply via perichondrium
Types of Cartilage
  1. Hyaline Cartilage
    • Most abundant; appears as shiny bluish glass.
    • Location: ends of long bones, nose, trachea, larynx, ribs.
  2. Elastic Cartilage
    • Contains more elastic fibers.
    • Location: external ear, epiglottis.
  3. Fibrocartilage
    • Properties between hyaline and dense regular tissue; provides tensile strength.
    • Location: intervertebral discs, knee joints, pubic symphysis.

Bone

  • Also known as osseous tissue.
  • Functions:
    • Supports and protects body structures
    • Stores fat and synthesizes blood cells in cavities.
  • Composition: More collagen than cartilage, inorganic calcium salts.
  • Highly vascularized
  • Osteoblasts produce the matrix; osteocytes maintain it in lacunae.

Blood

  • Unique as a fluid connective tissue.
  • Contains:
    • Red blood cells (erythrocytes)
    • White blood cells (leukocytes)
    • Platelets
  • Solid proteins that precipitate during clotting.
  • Functions: Transport of gases, nutrients, and waste.

Muscle Tissue

  • Highly vascularized; responsible for various types of movement.
  • Muscle cells contain myofilaments (composed of actin and myosin).

Types of Muscle Tissue

  1. Skeletal Muscle
    • Voluntary control, multi-nucleated, striated.
    • Location: Attached to bones.
  2. Cardiac Muscle
    • Involuntary control, striated, typically single nucleus with intercalated discs.
    • Location: Walls of the heart.
  3. Smooth Muscle
    • Involuntary control, non-striated, spindle-shaped cells.
    • Location: Walls of hollow organs (e.g., digestive tract).

Nervous Tissue

  • Composed of the brain, spinal cord, and nerves.
  • Functions to regulate and control body functions.
  • Made up of:
    • Neurons (conduct electrical signals)
    • Supporting cells (insulate and protect neurons).

Covering and Lining Membranes

  • Composed of at least two primary tissue types:
    • An epithelium bound to underlying connective tissue.
    • Types include:
    1. Cutaneous Membranes (Skin)
    2. Mucous Membranes (Line cavities open to exterior)
    3. Serous Membranes (Closed body cavities)

Tissue Repair

  1. Inflammation sets the stage: chemical release causes blood vessel dilation.
  2. Organization restores blood supply: blood clot replaced with granulation tissue.
  3. Regeneration and Fibrosis: Scab detaches, fibrous tissue matures, epithelial thickens.

Regenerative Capacity of Tissues

  • Well-regenerating: Epithelial, bone, areolar connective tissue, blood-forming tissue.
  • Moderate capacity: Smooth muscle and dense regular connective tissue.
  • Minimal capacity: Cardiac muscle, nervous tissue of brain & spinal cord.

Developmental Aspects of Tissues

  • Primary germ layers:
    • Ectoderm: Nerve tissue.
    • Mesoderm: Muscle and connective tissues.
    • Endoderm: Epithelial tissues.
  • Aging effects: Tissue thinning, less efficient repair, atrophy of bone/muscle/nervous tissue, increased cancer risk due to DNA mutation.