Integumentary System: Structure, Functions, and Variations in Vertebrates

What are the primary functions of the integumentary system?

Protection, respiration, streamlining movement, camouflage, mimicry, defense, fluid loss/osmoregulation, temperature regulation, waterproofing, hunting/prey capture, courtship displays, nourishment of young, chemical signaling, and filtering food.

What is the outer layer of the skin called?

Epidermis.

What are the main features of the epidermis?

Mucus secretions in fish and amphibians, outer keratin layer in reptiles, mammals, and birds, and it derives from ectoderm.

What is keratin?

A fibrous structural protein unique to chordates, essentially insoluble in water, and comprises many skin derivatives.

What is the inner layer of the skin called?

Dermis.

What does the dermis derive from?

Mesoderm.

What are the main components of the dermis?

Loosely arranged collagen, nerves, and blood vessels.

What are the distinct layers of collagen fibers in the dermis called?

Plies.

What is the function of mucus secretion in fish skin?

Protection (physical slipperiness, antibacterial, antiparasitic) and streamlining.

What are the types of scales found in bony fish?

Cosmoid, ganoid, and teleost scales.

What are the characteristics of cosmoid scales?

Thick layer of dentin with a thin enamel covering.

What are the characteristics of ganoid scales?

Thick enamel-like structure without dentin.

What are the characteristics of teleost scales?

No enamel or dentin, only lamellar (acellular) bone.

What are placoid scales?

Scales derived from the dermis, also called dermal denticles, that penetrate the epidermis.

What is the function of placoid scales?

Hydrodynamics (reduce drag during swimming) and protection.

What is ecdysis in reptiles?

The process of shedding the outer layer of keratinized epidermis.

What are the differences in scale origin between fish and reptiles?

Fish scales are of dermal origin and do not penetrate the epidermis, while reptile scales are of epidermal origin.

What adaptations do amphibians have in their integumentary system?

Cutaneous respiration, mucus glands for moisture retention, and poison glands.

What is the clinical significance of skin scraping in fish?

It is used for diagnosing skin diseases and conditions.

What is the significance of dermal bones in reptiles?

They provide support for abdominal muscles and are referred to as gastralia.

What is the role of chromatophores in fish?

They are present in the dermis and help display true color.

What are the adaptations of birds' integumentary systems?

Feathers for flight and uropygial glands for waterproofing.

What is the significance of mammary glands in the integumentary system?

They are involved in the nourishment of young.

What are the types of skin glands found in reptiles?

Fewer in number, confined to specific areas, and include scent glands.

What is the clinical significance of amphibian anesthesia?

Cutaneous respiration allows for immersion anesthesia, and pulmonary respiration may cease during anesthesia.

What adaptations do reptiles have compared to amphibians?

Increased keratinization, fewer skin glands, and scales of epidermal origin.

What are the variations in ecdysis among reptiles?

Turtles and crocodiles shed pieces of keratinized layer intermittently, while snakes and some lizards shed a thicker layer that often remains intact.