Integumentary System

Integumentary Structures

Includes skin (epidermis and dermis), scales, feathers, hair, glands, claws, nails, hooves, horns, antlers, vibrissae, baleen.

Functions of Integumentary Structures

Protection, thermoregulation, sensory input, camouflage, waterproofing, and communication.

Epidermis

Outer layer of the skin derived from ectoderm, containing keratin.

Dermis

Inner layer of the skin derived from mesoderm, containing collagen, nerves, blood vessels.

Basement Membrane

A structure that separates the epidermis from the dermis.

Subcutaneous Tissue

Tissue located beneath the dermis and above underlying muscle.

Keratin

A fibrous structural protein that provides strength and waterproofing, found in reptiles, birds, and mammals.

Types of Fish Scales

Cosmoid, ganoid, teleost (cycloid and ctenoid) scales.

Placoid Scales

Scales found in cartilaginous fish that penetrate the epidermis.

Ectoderm

The embryological origin of the epidermis.

Mesoderm

The embryological origin of the dermis.

Amphibian Skin Characteristics

Thin skin, lacks dermal scales, has capillary beds for respiration, mucus and poison glands.

Reptile Scales

Epidermal folds that are keratinized; include scutes.

Scutes

Large epidermal scales in reptiles with underlying bone.

Ecdysis

The shedding of the outer keratinized epidermis, varying among reptile groups.

Avian Integument Features

Thin epidermis, keratin scales on legs, feathers, minimal glands.

Pterylae

Feather tracts on birds.

Apteria

Featherless areas on birds.

Types of Feathers

Flight, tail, down, contour, semiplume, bristle, filoplume.

Structure of a Flight Feather

Includes calamus, rachis, barb, barbule, hook, and vane.

Uropygial Gland

Preening gland that secretes a substance for waterproofing and conditioning feathers.

Hair Structure

Consists of a keratinous strand with a shaft and root, growing from epidermal follicle in dermis.

Guard Hairs vs Undercoat Hairs

Guard hairs are coarse and visible; undercoat hairs are fine and numerous for insulation.

Types of Exocrine Glands in Mammals

Sebaceous, eccrine, and apocrine glands with specific secretions and functions.

Functions of Apocrine Glands

Include scent glands for communication, mammary glands for milk secretion, and anal glands for marking.

Differences in Hooves, Claws, Nails, and Talons

Hooves encase the digit; nails protect tips; claws/talons are for grasping.

Horns vs Antlers

Horns are permanent with a keratin sheath, found in both sexes; antlers are shed annually, typically found in males.

Baleen

Keratin plates in whales used for filter feeding.

Vibrissae

Sensory hairs/whiskers that detect touch and vibration.

Basement Membrane Location

Separates epidermis from dermis, providing structural support.

Chromatophores

Pigment cells in the dermis of fish and amphibians responsible for coloration.

Iridophores

Specialized chromatophores that produce color via light refraction.

Ply in the Dermis

Distinct layers of collagen fibers that enhance flexibility, strength, and streamline in aquatic species.