Histology Reviewer Lecture Notes

Introduction to Histology

• Histology: Study of tissues.
• Tissues: Groups of similar cells performing specific functions.

Classifications of Animal Tissues

1. Epithelial Tissues
   • Functions: Protection, secretion, sensation.
2. Connective Tissues
   • Functions: Connection and support.
3. Muscular Tissues
   • Function: Movement.
4. Nervous Tissues
   • Function: Communication.

Epithelial Tissues

• Found at the outermost layer.
• Characteristics: Covers surfaces and cavities, includes basal membrane, can be simple or stratified.
• Types:
  • Simple Squamous Epithelium
    • Thin, flat polygonal cells.
    • Locations: Air sacs of lungs, lining of blood vessels.
  • Stratified Squamous Epithelium
    • Multiple layers of polygonal cells.
    • Locations: Skin, mouth lining, vaginal lining, esophageal lining.
  • Simple Columnar Epithelium
    • Taller than wide cells.
    • Locations: Lining of the intestine & upper respiratory tract.
  • Simple Cuboidal Epithelium
    • Cube-like cells.
    • Locations: Lining of kidney tubules, gland ducts.
  • Ciliated Pseudostratified Columnar Epithelium
    • Single layer appearing stratified with cilia.
    • Locations: Trachea, ducts of many glands.

Connective Tissues

• Functions: Join tissues, support body & organs.

• Components:

  • Cells: Few in number (e.g., fibroblasts, macrophages).
  • Fibers: Collagen (white) , elastic (yellow) , reticular (branched, delicate support)
  • Amorphous Ground Substance: Matrix from liquid to solid state.

• Types:

  • Connective Tissue Proper

    • Loose/Areolar CT: Elastic fibers, widely distributed.
    • Dense/Fibrous CT: Densely packed collagen (tendons, ligaments, dermis).

  • Specialized Connective Tissue

    • Elastic Tissue: Parallel elastic fibers (vertebral column, lung tissue).
    • Adipose Tissue: Fat storage (subcutaneous layer, around organs).
    • Vascular Tissue/Blood: Composed of plasma and formed elements.

  ##-**Erythrocytes : RBC

  ##-**Leucocytes : WBC -**Granulocytes/ Polymorphonuclear Leucocytes -**Neutrophil - multi-lobed (polymorphic) -**Eosinophil - 2 lobed (polymorphic) -**Basophil - 3 lobed (s shape). -**Agranulocytes / mononuclear leucocytes -**Lymphocyte (20-25%) - nucleus entire cell -**monocyte (2-6%) - bean shape, phagocytes

  ##-**Thrombocytes : platelets.

##- Supporting Connective Tissue - Cartilage: Includes hyaline, elastic, fibro-cartilage. - Bone or Osseus Tissue: Structural support, includes osteons.

Muscular Tissues

• Functions: Shape, movement, and locomotion.
• Types:
  • Skeletal Muscle: Striated, voluntary, attached to skeleton.
  • Smooth Muscle: Non-striated, involuntary, found in digestive tract walls.
  • Cardiac Muscle: Striated, involuntary, heart muscle with intercalated disks.
• Structure:
  • Sarcolemma: Muscle membrane.
  • Sarcoplasm: Cytoplasm.
  • Myofibrils: Contractile filaments with thick (myosin) and thin (actin) filaments.
  • Sarcomeres: Contractile units.

Nervous Tissues

• Specialized for impulse transmission and body activity integration.
• Functions:
  1. Sense changes.
  2. Interpret and remember changes.
  3. React to changes.
• Components:
  • Neurons: Conduct impulses.
  • Glial Cells: Support neurons.
• Neuron Types:
  1. Sensory Neurons: Respond to environment.
  2. Interneurons: Connect neurons for integration.
  3. Motor Neurons: Send signals from CNS to effectors.
• Neuron Structure:
  • Multipolar: Several dendrites, one axon.
  • Bipolar: One dendrite, one axon.
  • Unipolar: One process, always sensory.

Additional Visuals

• Drawings and labels for various types of tissues and cells were mentioned for practical understanding.

Note: The lecture included drawings and visual aids to help illustrate certain concepts, though precise accuracy of these parts is not verified.

These notes provide a comprehensive overview of tissue types and their characteristics, serving as a useful reference for studying histology.