Page 1: Tissue Overview

Tissue: The Living Fabric

• Introduction to tissue study

• Focus on types and functions of tissues

Page 2: Tissue Basics

Introduction to Tissues

• Definition: Group of cells with similar structure and function

• Histology: Study of tissues

• Types of Tissues:

  • Epithelial

  • Connective

  • Muscle

  • Nervous

Page 3: Types of Tissues

Nervous Tissue

• Function: Internal communication

• Found in: Brain, spinal cord, nerves

Muscle Tissue

• Function: Contracts to cause movement

• Types:

  • Skeletal (attached to bones)

  • Cardiac (muscles of heart)

  • Smooth (muscles of hollow organs)

Epithelial Tissue

• Forms boundaries, protects, secretes, absorbs, filters

• Examples: Skin surface, GI tract linings

Connective Tissue

• Supports, protects, binds other tissues

• Examples: Bones, tendons, fat

Page 4: Epithelial Tissue Types

Types of Epithelium

• Two main types based on location:

  1. Covering and lining epithelia: External and internal surfaces

  2. Glandular epithelia: Secretory tissue in glands

Page 5: Epithelial Tissue Characteristics

Key Characteristics

1. Polarity: Apical (free) and basal (attached) surfaces

   • Apical may have microvilli (e.g., intestinal lining) or cilia (e.g., trachea)

2. Cell Structure: Closely packed cells forming continuous sheets

3. Support: Underlied by connective tissue reticular lamina

4. Avascular but Innervated: Lacks blood vessels but has nerve endings

5. Regeneration: High regenerative capacity

Page 6: More Characteristics of Epithelial Tissue

• Reiterates characteristics from previous page, emphasizing close packing and support by connective tissue.

Page 7: Epithelial Classification

Classification Framework

• Questions to classify:

  1. Number of layers:

     • 1 = simple epithelium

     • 1 = stratified epithelium

Page 8: Apical and Basal Surfaces

Surface Identification

• Differentiation between simple and stratified based on layers

Page 9: Cell Shapes in Epithelia

Classifying by Cell Shape

• Cell shapes:

  • Squamous

  • Cuboidal

  • Columnar

• Note: If stratified, name according to the apical layer.

Page 10: Cell Shape Visuals

Visual Examples

• Illustrations of squamous, cuboidal, and columnar cells

Page 11: Types of Epithelial Cells

Specific Epithelial Types

• Types of Epithelia Include:

  • Simple squamous

  • Simple cuboidal

  • Simple columnar

  • Pseudostratified columnar

  • Stratified squamous

  • Transitional

  • Glandular

Page 12: Overview of Epithelial Tissues

Epithelial Tissue Summary Framework

• For each type:

  • Description

  • Function

  • Location

Page 13: Simple Squamous Epithelium

Characteristics

• Description: Single layer of flattened cells

• Function: Diffusion, filtration, lubricates surfaces

• Location: Kidney glomeruli, lung air sacs, blood vessel linings

Page 14: Locations for Simple Squamous

Additional Locations

• Endothelium: Lining of blood vessels

• Mesothelium: Epithelium of serous membranes

Page 15: Simple Cuboidal Epithelium

Characteristics

• Description: Single layer of cubelike cells

• Function: Secretion and absorption

• Location: Kidney tubules, ducts of glands, ovary surface

Page 16: Simple Columnar Epithelium

Characteristics

• Description: Single layer of tall cells, may have cilia

• Function: Absorption, secretion of mucus and enzymes

• Location: Digestive tract lining, some glands

Page 17: Pseudostratified Columnar Epithelium

Characteristics

• Description: Single layer of varied height cells

• Function: Secretion and propulsion of mucus

• Location: Trachea, upper respiratory tract, male ducts

Page 18: Stratified Squamous Epithelium

Characteristics

• Description: Thick membrane of multiple cell layers

• Function: Protects areas subject to abrasion

• Location: Linings of esophagus, mouth, vagina; epidermis of skin

Page 19: Stratified Cuboidal Epithelia

Characteristics

• Rare in body, typically two cell layers thick

• Found in some glands (sweat, mammary)

Page 20: Stratified Columnar Epithelia

Characteristics

• Limited distribution, found in pharynx and male urethra

Page 21: Transitional Epithelium

Characteristics

• Description: Can resemble various shapes due to stretching

• Function: Allows stretching of urinary organs

• Location: Urinary bladder, ureters

Page 22: Glandular Epithelia

Introduction to Glands

• Definition: One or more cells that secrete fluids

• Classification:

  • By product release site (endocrine or exocrine)

  • By number of cells (unicellular or multicellular)

Page 23: Endocrine Glands

Characteristics

• Ductless, secrete hormones into blood or lymph

Page 24: Exocrine Glands

Characteristics

• More numerous than endocrine, secrete into ducts

• Release products on surfaces or into cavities (sweat, salivary)

Page 25: Unicellular Exocrine Glands

Goblet Cells

• Example: The only important unicellular gland

Page 26: Exocrine Glands Structure

Cellular Components

• Microscopic Structure: Secretory vesicles, rough ER, Golgi apparatus

Page 27: Pseudostratified Columnar Epithelium Detail

Reiteration of Function and Location

• Similar details as before for clarity.

Page 28: Multicellular Exocrine Glands

Composition and Classification

• Composed of duct + secretory unit

• Classified by:

  • Duct type (simple or compound)

  • Secretory unit structure

Page 29: Various Duct Structures

Examples of Multicellular Glands

• Types:

  • Simple tubular

  • Compound tubular

  • Compound alveolar

  • And more with examples

Page 30: Modes of Secretion

Secretion Types

• Merocrine: Secreted by exocytosis (e.g., pancreas)

• Holocrine: Secreted by rupture of gland cells (e.g., sebaceous)

Page 31: Visuals of Secretion Modes

Images of Secretion Processes

• Illustrates merocrine and holocrine secretion visually.