TISSUES

Tissue: A DefinitionA group of connected, interdependent cells that cooperate to perform a specific function

Categories of Tissue1. Epithelial Tissue

2. Connective Tissue

3. Muscle Tissue

4. Nervous Tissue

Epithelial Tissues• General FeaturesCellular Layer +

Basement Membrane

Epithelial Tissues• General FeaturesCellular Layer + Basement Membrane

No Direct Circulation/Blood Supply

Touch Each Other

Rapid Rate of Cell Reproduction

Epithelial Tissues• Structural Classification

Cell Shapes

Columnar

Cuboidal

Squamous

Epithelial Tissues• Structural Classification

Cell Shapes

Cell Layers

Simple

Stratified

Epithelial Tissues• Major Types

Simple Squamous Epithelium

Simple Squamous EpitheliumFunction: Exchange

Sample Locations: Alveoli, capillaries

Stratified Squamous Epithelium

Stratified Squamous Epithelium

Function: Protection

Sample Locations: Skin, Mouth, Repro tracts

Simple Cuboidal Epithelium

Function: Absorption or Secretion

Sample Locations: Kidney, Hormone Glands

Simple Columnar Epithelium

Function: Absorption (or Secretion)

Sample Location: Digestive Tract

Microvilli

Simple ColumnarNote goblet cells

Pseudostratified Columnar Epithelium

Note cilia

Pseudostratified Columnar Epithelium

Pseudostratified Columnar EpitheliumFunction: Absorption, Secretion, Movement

Sample Locations: Respiratory & Repro Ducts

Transitional EpitheliumFunction: Stretchability

Sample Location: Urinary Bladder

What kind of tissue is this?

Epithelium cont.

• Epithelium that lines cavities sits on lamina propria.– Supports epithelium

– Binds epithelium to other tissue

– Provides nutrition

• Sides of cells are named– Basal

– Apical (free)

– Lateral

Basal Lamina-Lamina Propria

Intercellular Junctions

Belts that circle cell.ZO (tight junction) acts as barrier. ZA provides for adhesion of one cell to another

SpotsDes is like a spot welding.Gap allows passage of chemical for communication.

Gap Junction

Specializations of Cell Surface

• Microvilli– Found mainly on absorptive cells– Brush border, 1high

• Cilia / flagella– Cylindrical, motile structures, 5-10high– Contain microtubules– Basal bodies

Microvilli

Apical region of an intestinal epithelial cell seen with TEM. Filaments that constitute the core of the microvilli are clearly seen. An extracellular cell coat (glycocalyx) is bound to the plasmalemma of the microvilli. x45,000.

Cilia