week 2 LSB421 lecture 3

Types of Body Tissue

Overview

• Four main types of body tissue: Epithelial, Connective, Muscle, and Nervous tissue.

Epithelial Tissue

• Characteristics:

  • Composed of tightly packed cells that form continuous sheets or linings.

  • Serves as barriers or interfaces between different body environments.

• Structure:

  • Consists of cells with apical (outer) and basal (inner) surfaces.

  • Apical surface interacts with the external environment, providing protection.

  • Basal surface connects deeper body tissues.

• Function:

  • Acts as a protective barrier and interface with external factors.

  • Example: Skin epithelium protects against physical, chemical, and microbial threats.

• Classification:

  • Simple Epithelia: Single layer of cells.

    • Simple Squamous Epithelium:

      • Composed of flattened cells.

      • Locations: Alveoli of lungs, abdominal cavity lining, endothelium of blood vessels.

      • Function: Allows rapid diffusion of substances.

    • Cuboidal Epithelium:

      • Single layer of cube-shaped cells.

      • Locations: Kidney tubules, various secretory glands.

      • Function: Secretion and absorption.

    • Columnar Epithelium:

      • Single layer of tall, slender cells.

      • Locations: Lining of certain kidney ducts, stomach, intestines.

      • May have microvilli to increase surface area.

  • Stratified Epithelia: Multiple layers of cells.

    • Stratified Squamous Epithelium:

      • Provides mechanical and chemical protection.

      • Locations: Skin surface, mouth, throat, anus, rectum.

    • Stratified Cuboidal Epithelium:

      • Rare, found in ducts of exocrine glands (e.g., sweat glands).

    • Stratified Columnar Epithelium:

      • Rare, found in lining dental ducts, pancreas, and salivary glands.

  • Transitional Epithelium:

    • Stratified tissue capable of stretching.

    • Location: Urinary bladder.

    • Characteristics: Cells change shape when bladder fills (cuboidal when relaxed, squamous when stretched).

Connective Tissue

• Function:

  • Provides structural support and connects various body parts.

  • Comprises a matrix of cells and extracellular material.

Muscle Tissue

• Function:

  • Responsible for producing force and enabling movement.

  • Composed of cells capable of contraction and relaxation.

Nervous Tissue

• Function:

  • Composed of specialized cells (neurons) that transmit electrical signals.

  • Allows for communication and coordination within the body's control.