Lecture Notes: Introduction to Tissues

Definition of Tissue

• Group of similar cells and cell products
• Perform specific structural and physiological roles in organs

Classification of Tissues

• Four primary categories:
  • Epithelial Tissue
  • Connective Tissue
  • Nervous Tissue
  • Muscular Tissue

Characteristics Differentiating Tissues

• Type and function of constituent cells
• Characteristics of the matrix (substance around cells)
• Ratio of the matrix to cells

Detailed Overview of Tissue Types

1. Epithelial Tissue

• Structure: Layers of closely spaced cells, minimal matrix
• Function:
  • Covers body surfaces (external skin and organ linings)
  • Roles include protection, secretion, excretion, filtration, and absorption
  • Found abundantly in glands and kidneys

2. Nervous Tissue

• Structure: Neurons and glial cells
• Function:
  • Transmits signals and information
  • Acts as communicators throughout the body

3. Muscular Tissue

• Structure: Composed of elongated excitable cells
• Function:
  • Specialized for contraction and movement
  • Essential for digestion, waste elimination, breathing, speech, and blood circulation
• Types of Muscle Tissue:
  • Skeletal Muscle: Voluntary, helps with movement (e.g., bending arm)
  • Cardiac Muscle: Involuntary, contracts to pump blood
  • Smooth Muscle: Involuntary, lines blood vessels and intestines

4. Connective Tissue

• Structure: Cells surrounded by extracellular matrix
• Function:
  • Connects, separates, and supports other tissue types
  • Cells are loosely packed
• Types:
  • Connective Tissue Proper: Divided into loose and dense connective tissue
  • Specialized Connective Tissue: Includes blood, bone, and cartilage

Organ Level Organization

• Organs are composed of several tissue types
• Example organs: spleen, skin, heart

Summary

• Four types of tissues in the body: epithelial, connective, muscular, and nervous
• Each type will be explored in more detail in separate videos.