Histology
Histology Summary
Learning Objectives
- Understand tissue formation, cell adhesion, and classification of epithelial and connective tissues.
- Identify epithelial and connective tissues’ locations and functions.
- Discuss muscle and nervous tissue characteristics.
- Define and describe types of body membranes.
Tissue Assembly
- Cells reassemble via selective cell-cell adhesion; similar cells preferentially adhere together.
Cell-Cell Adhesion Molecules (CAMs)
- Essential for cell adhesion and structure integrity of tissues.
- Involves the basement membrane and intercellular cement (proteoglycans).
Types of Cell Junctions
- Four main types: gap, tight, intermediate (adherens), and desmosomes.
- These junctions anchor cells to each other or to the extracellular matrix (ECM).
- Composed of proteins, polysaccharides, and secreted by connective tissue cells (fibroblasts, chondroblasts, osteoblasts).
- Functions: bind cells, influence growth/development, and maintain cell polarity.
Components of ECM
- Proteins: glycosaminoglycans (GAGs), fibrous proteins (collagen, elastin), adhesive proteins (fibronectin, laminin).
Tissue Types
- Four main types: epithelial, connective, muscular, and nervous.
Epithelial Tissue
- Characterized by: high cellularity, avascular, polarity, and fast regeneration.
- Classified by cell shape (squamous, cuboidal, columnar) and layers (simple, stratified).
Connective Tissue
- Composed of diverse cell types and ECM.
- Functions: support, protection, energy storage, and transport.
- Types: loose, dense (regular and irregular), fluid (blood and lymph), supportive (cartilage and bone).
Muscle Tissue Types
- Skeletal: striated, voluntary, multinucleated.
- Cardiac: striated, involuntary, intercalated discs.
- Smooth: non-striated, involuntary.
Nervous Tissue
- Composed of neurons (information transmission) and neuroglia (support & nourish neurons).
Body Membranes
- Types: serous, mucous, cutaneous, and synovial.
- Functions include protection and secretion.