1- Integument

Integumentary System Components

Skin Layers

  • Epidermis: The outermost layer of skin, providing a barrier against the environment.

  • Dermis: The layer beneath the epidermis, containing connective tissue, hair follicles, and glands.

  • Hypodermis: The deepest layer that connects the skin to underlying tissues.

Epidermal Structures

  • Stratum Corneum: Outermost layer of the epidermis; composed of dead skin cells.

  • Stratum Basale (Germinativum): The deepest layer of the epidermis where cell division occurs.

  • Basement Membrane: Thin layer separating the epidermis from the dermis.

  • Stratum Laxum: Loose connective tissue layer in the dermis.

  • Stratum Compactum: Dense connective tissue layer providing strength and structure.

Hair and Fur Components

  • Underhair: Short, soft hair providing insulation (wool and fur).

  • Guard Hairs (Spines, Bristles, and Awns): Longer, protective hair.

  • Vibrissae: Whiskers used for tactile sensation.

  • Angora Growth: Continuous growth of hair or fur.

  • Definitive Growth: Hair/fur grows to a certain length and then stops.

Glands

  • Sweat Glands: Glands that produce sweat for thermoregulation.

  • Sebaceous Glands: Produce oil to lubricate skin and hair.

  • Scent (Musk) Gland: Used for communication and marking territory.

  • Mammary Gland: Produces milk in females.

  • Mucus Gland: Produces mucus for lubrication and protection.

  • Poison Gland: Produces toxic secretions for defense.

  • Uropygial Gland: Oil gland in birds for feather maintenance.

Scale Types

  • Placoid Scale: Small, tooth-like scales found in cartilaginous fish.

  • Ganoid Scale: Rhombus-shaped and bony scales found in some fish.

  • Cycloid Scale: Thin, round scales overlapping in fish.

  • Ctenoid Scale: Similar to cycloid but with a spiny edge.

  • Dermal Scales: Formed from the dermis layer in some reptiles.

  • Epidermal Scales: Sheds from the epidermal layer in reptiles.

Other Appendages and Structures

  • Feathers: Specialized structures for insulation, flight, and display in birds.

    • Pterylae: Feather tracts on the bird's body.

    • Calamus: The hollow base of the feather.

    • Rachis: The central shaft of the feather.

    • Vane: The flat, webbed part of the feather.

    • Barbs: Branches coming off the rachis.

    • Barbules: Tiny structures on barbs that interlock feathers.

    • Pennaceous Feathers: Stiff feathers providing shape.

    • Plumulaceous Feathers: Soft, fluffy feathers providing insulation.

    • Contour Feathers: Covering and shaping the bird's body.

    • Semiplumes: Between contour and down feathers, providing insulation.

    • Down Feathers: Small, fluffy feathers for insulation.

    • Bristles: Stiff, hair-like feathers used for protection and sensory function.

    • Filoplumes: Hair-like feathers providing sensory feedback.

  • Hooves: Hard structures on the ends of digits in ungulates.

  • Claws: Sharp, curved structures at the tips of digits.

  • Horns: Permanent structures found in some mammals.

  • Antlers: Temporary structures found in deer, regenerative yearly.

  • Cornified Sheath: The outer layer of claws or horns.

  • Carapace: The upper shell of a turtle or tortoise.

  • Plastron: The lower shell of a turtle.

  • Osteoderms: Bony deposits forming scales, plates, or armor in reptiles.