Animal tissues and their functions

• Levels of organization in the vertebrate body

  • Cells
  • Tissues
  • Organs
  • Organ systems
• Organs are body structures composed of several different tissues that form a structural and functional unit
• An organ system is a group of organs that function together to carry out the major activities of the body
• Major vertebrate organ systems

  • Integumentary System
  • Nervous System
  • Endocrine System
  • Muscular System
  • Skeletal System
  • Circulatory System
  • Lymphatic System
  • Respiratory System
  • Digestive System
  • Urinary System
  • Reproductive System
• Tissues


  Groups of cells which have similar structure and function
• Fundamental embryonic tissues (germ layers)

  • Endoderm
  • Mesoderm
  • Ectoderm
• Primary tissues


  • Epithelial
  • Connective
  • Muscle
  • Nervous
• Epithelial tissue


  Forms membranes and glands, covers every surface of the vertebrate body
• Epithelial tissue


  • Cells are tightly bound together, with very little space between them
  • Nutrients and oxygen diffuse to the epithelial cells from blood vessels in nearby tissues
  • Epithelium possesses remarkable regenerative potential
• Types of epithelial tissues

  • Simple epithelial membranes
  • Stratified epithelial membranes
  • Exocrine glands
  • Endocrine glands
• Endocrine glands


  Ductless glands, their secretions (hormones) enter blood capillaries and stay within the body
• Connective tissue


  Abundant extracellular material, cells are spaced widely apart
• Classes of connective tissue

  • Connective tissue proper (loose and dense)
  • Special connective tissues (cartilage, bone, blood)
• Loose connective tissue


  • Holds organs in place, attaches epithelial tissue to other underlying tissues
• Dense connective tissue


  • Tightly packed collagen fibers, stronger than loose connective tissue
• Muscle tissue


  Responsible for motion, maintenance of posture, heat production
• Types of muscle tissue

  • Smooth muscle
  • Skeletal muscle
  • Cardiac muscle
• Smooth muscle


  • Found in the organs of the internal environment, contraction is generally involuntary
• Skeletal muscle


  • Attached to bones by tendons, contraction is under voluntary control
• Cardiac muscle


  • Composed of interconnected cells with single nuclei, contraction is spontaneous and coordinated
• Nervous tissue


  Controls and integrates all body activities, transmits signals, coordinates and regulates body functions
• Neurons


  • Specialized to produce and conduct electrochemical impulses
• Neuroglia/glial cells


  • Support and insulate neurons, eliminate foreign materials