Lecture on Animal Tissues

Introduction

• Focus on the relationship between tissue function and shape
• Four main types of tissues:
  1. Connective
  2. Epithelial
  3. Muscle
  4. Nervous
• Discussion on subdivisions and identification

Epithelial Tissue

• Structure
  • Simple (one layer) or stratified (multi-layered)
  • Protective layer with a basement membrane
  • Few intercellular spaces
• Functions
  • Protection and lining of internal/external surfaces
• Identification
  • Nucleus shapes (circular, elongated)
  • Geometric shapes (square, rectangular)
• Types
  1. Squamous Epithelium
     • Thin, flat cells, often with a flattened nucleus
     • Locations: Mouth lining, alveoli, skin surface
     • Rapid healing for protection
  2. Columnar Epithelium
     • Elongated, rectangular cells with oval-shaped nucleus
     • May have cilia (increased surface area)
     • Locations: Intestines, gall bladder
  3. Cuboidal Epithelium
     • Square shape with spherical nucleus
     • Found in tubes, for absorption/secretion
     • Locations: Sweat glands, thyroid gland, kidney tubes

Nervous Tissue

• Function: Conducts electrochemical signals
• Three Types of Neurons
  1. Sensory Neuron
     • Senses information (sight, hearing, etc.)
     • Cell body off to the side
  2. Motor Neuron
     • Controls movement (muscles)
     • Cell body in the center of dendrites
  3. Interneurons (Relay Neurons)
     • Between sensory and motor neurons
     • Found in spinal cord and brain

Connective Tissue

• Purpose: Support, stabilize, and protect organs
• Types
  1. Areolar Tissue
     • Binds epithelium, under skin
     • Contains collagen and elastic fibers
  2. Fibrous Connective Tissue
     • Dense non-elastic collagen fibers
     • Found in tendons, ligaments
  3. Cartilage
     • Prevents friction, absorbs shock
     • Smooth, glossy appearance
  4. Blood
     • Liquid connective tissue
     • Transports nutrients, hormones
  5. Adipose Tissue
     • Stores fat, insulates
     • Found around organs, under skin
  6. Bone
     • Solid tissue, structure of body
     • Made of osteocytes, provides framework

Muscle Tissue

• Types
  1. Skeletal Muscle
     • Striated, multi-nucleated
     • Voluntary movement, attached to bones
  2. Smooth Muscle
     • Non-striated, spindle-shaped fibers
     • Involuntary movement, found in digestive system
  3. Cardiac Muscle
     • Branched fibers, striated
     • Involuntary movement, found in heart only

Conclusion

• Review of tissue types and their functions
• Importance of shape in tissue identification and functionality
• Overview of the major tissues covered