Lab 3 - Histology: Epithelial Tissues Flashcards

Principles of Epithelial Tissue Classification

• Primary Rule of Epithelial Classification: Epithelium is classified based on the shape of the cells located at the apical surface, not by the shape of the cells at the basement membrane.
• Importance: This classification principle is particularly crucial when observing and identifying stratified epithelium, where cell shapes vary across different layers.
• Laboratory Exercise Overview: Exercise 1 requires examining slide boxes to view slides of various types of covering and lining epithelia under the microscope (Figure 4.8).

Covering and Lining Epithelia

Simple Epithelia

Simple Squamous Epithelium

• Main Functions: Diffusion, filtration, and secretion.
• Required Structures to Label & Identify:
  • Apical surface
  • Basal surface
  • Nucleus
  • Cell outline demonstrating the flat, thin shape of an epithelial cell
• Microscopic Appearance:
• Anatomical Location Check: Requires identifying at least one location of simple squamous epithelium in the body.

Simple Cuboidal Epithelium

• Main Functions: Absorption and secretion.
• Required Structures to Label & Identify:
  • Apical surface
  • Basal surface
  • Nucleus
  • Cell outline demonstrating the cube-like shape of an epithelial cell
• Anatomical Location Check: Requires identifying at least one location of simple cuboidal epithelium in the body.

Simple Columnar Epithelium

• General Functions: Absorption and secretion.
• Varieties: Simple columnar epithelium exists in two distinct functional varieties:
  1. Non-ciliated simple columnar epithelium
  2. Ciliated simple columnar epithelium

Non-Ciliated Simple Columnar Epithelium

• Required Structures to Label & Identify:
  • Apical surface
  • Basal surface
  • Nucleus
  • Cell outline demonstrating the tall, rectangular shape of an epithelial cell
• Microscopic Appearance:
• Anatomical Location Check: Requires identifying at least one location of non-ciliated simple columnar epithelium in the body.

Ciliated Simple Columnar Epithelium

• Main Function of Apical Cilia: The primary function of cilia on the apical surface is to help move substances or cells through an internal passageway.
• Required Structures to Label & Identify:
  • Apical surface
  • Basal surface
  • Cilia
  • Nucleus
  • Cell outline demonstrating the epithelial cell shape
• Anatomical Location Check: Requires identifying at least one location of ciliated simple columnar epithelium in the body.

Pseudostratified Columnar Epithelium

Pseudostratified Ciliated Columnar Epithelium

• Main Tissue Functions: Absorption and secretion.
• Main Function of Apical Cilia: The primary function of cilia on the apical surface is to help move substances on the apical surface, especially mucus.
• Required Structures to Label & Identify:
  • Apical surface
  • Basal surface
  • Cilia
  • Nucleus
  • Cell outline demonstrating the cell shape
• Microscopic Appearance:
• Anatomical Location Check: Requires identifying at least one location of pseudostratified ciliated columnar epithelium in the body.

Stratified Epithelia

Stratified Squamous Epithelium

• General Main Function: Protection of underlying tissues in areas subjected to abrasion.
• Varieties: Stratified squamous epithelium exists in two distinct varieties:
  1. Non-keratinized stratified squamous epithelium
  2. Keratinized stratified squamous epithelium

Non-Keratinized Stratified Squamous Epithelium

• Required Structures to Label & Identify:
  • Apical surface
  • Basal surface
  • Nucleus
  • Cell outline demonstrating epithelial cell shape
• Anatomical Location Check: Requires identifying at least one location of non-keratinized stratified squamous epithelium in the body.

Keratinized Stratified Squamous Epithelium

• Required Structures to Label & Identify:
  • Apical surface
  • Basal surface
  • Dead epithelial cells (surface layer)
  • Nucleus
  • Cell outline demonstrating epithelial cell shape
• Microscopic Appearance:
• Anatomical Location Check: Requires identifying the only location of keratinized stratified squamous epithelium in the body.

Stratified Cuboidal Epithelium

• Major Functions: Absorption, secretion, and protection.
• Required Structures to Label & Identify:
  • Apical surface
  • Basal surface
  • Nucleus
  • Cell outline demonstrating cell shape
• Anatomical Location Check: Requires identifying at least one location of stratified cuboidal epithelium in the body.

Stratified Columnar Epithelium

• Major Functions: Secretion, absorption, and protection.
• Required Structures to Label & Identify:
  • Apical surface
  • Basal surface
  • Nucleus
  • Cell outline demonstrating cell shape
• Microscopic Appearance:
• Anatomical Location Check: Requires identifying at least one location of stratified columnar epithelium in the body.

Transitional Epithelium

• Main Function: To stretch easily to allow stored urine to distend the urinary organ.
• Required Structures to Label & Identify:
  • Apical surface
  • Basal surface
  • Nucleus
  • Cell outline demonstrating cell shape
• Anatomical Location Check: Requires identifying at least one location of transitional epithelium in the body.

Glandular Epithelia

Definition and Organization of Glands

• Definition of a Gland: A secretory organ composed mainly of epithelium supported by various connective tissues.
• Definition of Glandular Epithelia: Consists of specialized epithelial cells that constitute the functional or secreting portion of glands.
• Glandular Secretions: The substances produced by glandular epithelia are generally termed glandular secretions. Specific names are assigned to these secretions based upon the specific gland producing them.

Classification of Glands

• Primary Classification Criterion: Glands of the body are classified primarily based upon where they release their secretions.
• Major Gland Types:
  1. Endocrine Glands: Glands that produce secretions that are released via exocytosis into the extracellular fluid and blood system.