Review Slides for Exam 1 (Chapter 4) - Tagged

Covering and Lining Epithelium
- Covering:
  - Example: Outer layer of skin
- Lining:
  - Example: Lining of body cavities (e.g., respiratory system)
Glandular Epithelium

Apical-basal polarity:
- Epithelial layers have an apical surface (top) and a basal surface (bottom)
- Apical Surface: The apical surface refers to the top layer of epithelial tissue, which is exposed to the body surface or the cavity of an organ. It is often specialized for specific functions, such as absorption, secretion, or sensation. Common modifications of the apical surface include microvilli (for increased surface area) and cilia (for movement of substances).
  Basal Surface: The basal surface is the bottom layer of epithelial tissue, which is attached to the underlying connective tissue via the basement membrane. This surface helps anchor the epithelial layer and plays a role in communicating with the connective tissue, facilitating functions like nutrient exchange and structural support.
Specialized lateral contacts:
- Present in covering and lining epithelium (not glandular epithelium)
- Desmosomes:
  - Cell adhesion structures providing strength
- Tight junctions:
  - Prevent passage of substances between cells
Avascular but innervated:
- Epithelial tissues lack blood vessels but have nerve endings
Supported by connective tissue:
- Epithelial tissue rests on a basement membrane
Regeneration:
- High capacity to regenerate and repair

Location:
- Separates epithelial tissue from connective tissue
Composition:
- Made up of basal lamina and reticular lamina
- Basal Lamina: The basal lamina is a thin, supportive layer of extracellular matrix found underneath epithelial tissues. It consists primarily of collagen, laminin, and other proteins, providing structural support to the epithelial cells. It acts as a selective barrier, regulating the movement of molecules between the epithelial tissue and the underlying connective tissue.
  Reticular Lamina: The reticular lamina lies beneath the basal lamina and is composed of a network of reticular fibers (also collagen fibers) produced by connective tissue cells. It provides additional strength and support to the tissue, anchoring the basal lamina to the underlying connective tissue.
  Appearance: Both laminae are typically thin and may not be visible without microscopic examination. The basal lamina appears as a clear, glassy layer, while the reticular lamina has a more fibrous, mesh-like structure, giving added texture and support beneath the epithelial layer.

Endothelium:
- Innermost lining of blood vessels, heart, and lymphatic vessels
Mesothelium:
- Epithelium lining the serous membranes that cover the organs in the ventral body cavity

Based on Location of Product Release:
- Exocrine Glands:
  - Release products onto body surface (e.g., skin) or into body cavities
- Endocrine Glands:
  - Release products (hormones) into the bloodstream
Number of Cells:
- Unicellular:
  - Single cell (e.g., goblet cells)
- Multicellular:
  - Composed of multiple cells

Characteristics:
- Ductless; secrete hormones directly into the bloodstream
- Types of hormones produced:
  - Amino acids, peptides, glycoproteins, steroids
- Hormones stimulate specific target organs
- Mostly multicellular but some are a collection of cells
- Structural features vary; not always derived from epithelium

Function:
- Secretion either onto body surfaces or into cavities (e.g., digestive system)
- Can be unicellular or multicellular

Main Classes:
- Four main classes of connective tissue exist
Common Characteristics:
1. Contains a nonliving extracellular matrix made up of ground substance and fibers
2. All connective tissues arise from mesenchyme (embryonic tissue)
Vascularization Differences:
- Cartilage: Avascular
- Fat tissue: Rich blood supply
- Dense connective tissue: Poor blood supply

Components:
- Ground Substance
- Fibers:
  - Fibrous elements that provide support
- Cells:
  - Various cellular elements within the tissue