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Integumentary System

Integumentary System

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Integumentary System

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  1. Integumentary System • Protection & support • Sensory • Respiratory (amphibians) • Thermoregulation • Dissipate heat (blood vessels, sweat) • Conserve heat (blood vessels, hair, feathers)

  2. Locomotion • Water balance • Protective coloring, behavior • Vitamin D synthesis

  3. Epidermis • Ectodermal derivative • nonvascular

  4. Epidermis • Stratum germinativum • Deeper layer • Mitosis

  5. Epidermis • Superficial layer • Mucus cells (amphibians, fish) • Proteinaceous cells/granular glands • Slime, poisons, enamels, photophores, pheromones • Keratin (cornified, horny, stratum corneum) – Tetrapod feature

  6. Epidermis • Glands are epidermal in origin

  7. Dermis • Dermatome (mesoderm) in origin • Lateral/ventral mesoderm • Neural crest cells for pigment

  8. Dermis • Collagen for strength • Mucopolysaccharides • Elastic fibers • Smooth muscle • Blood and lymph vessels • Follicles and bases of gland

  9. Dermis • Dermis has ancient potential in forming bone as in this ostracoderm!

  10. Hard or Mineralized Tissues • Enamel • Dentin • Bone • Lamellar = Compact • Spongy

  11. Hard tissues • Bone is very primitive dating back to the ostracoderms

  12. Dermis • Chromatophores • Dermal in origin • From neural crest cells • Homeotherms have melanophores & pigment is INJECTED into epidermis • Poikilotherms – the pigment stays in the dermis

  13. Dermis - Chromatophores • Iridophores – silvery & iridescent • Xanthophores – yellow • Erythrophores - red

  14. Fish Skin - Epidermis • Cyclostomes – thin with unicellular mucus glands • Jawed fish – unicellular mucus glands, no keratin!, photophores in some

  15. Fish Dermis • Cyclostomes – no scales • Ostracoderms & Placoderms • Armor shields

  16. Ostracoderm Armor • Lamellar bone • Spongy bone • Dentin(e) • Enamel

  17. Armor Shield • Denticle – Elevations capped with enamel • Protection • Mineral reservoir

  18. Fish Dermis • Cosmoid scales • Modified dentin layer called Cosmine • Extinct sarcopterygians

  19. Fish Dermis • Ganoid scales • Modified thick enamel layer called ganoine • Found in gars

  20. Ganoid scale

  21. Fish Dermis • Placoid scales • Chondrichthyes • Denticle points reduce friction • Ancestor to teeth

  22. Placoid Scales Dentin Pulp Pulp cavity Epidermis

  23. Fish Dermis • Modern scales • Acellular • Thin lamellar bone only • Teleosts and modern sarcopterygians • Annual rings allows aging of fish

  24. Cycloid & Ctenoid Scales

  25. Cycloid scale

  26. Ctenoid scale

  27. Key Points • Give two major characteristics of fish skin.

  28. Amphibians • No scales • Multicellular glands (mucus) • Stratum corneum – keratin – tetrapod feature

  29. Amphibian Epidermis • Thin • Stratum corneum with keratin • Mucus and granular glands

  30. Integument Epidermis Mucus gland Poison gland Dermis

  31. Amphibian Dermis • Firmly attached • May have chromatophores • (Caecilians may have bony dermal scales)

  32. Key Points • Give 2 major characteristics of amphibian skin

  33. Reptile Skin • THICK stratum corneum • Epidermal scales in all • Horny (keratinized)surface structures • Very few glands, dry skin • Some have bony dermal scales or plates