INTEGUMENTARY SYSTEM OF

VERTEBRATES

THE SKINTHE SKIN (in general) (in general)

The skin technically refers to the vertebrate integumentIt has the same basic structure in all vertebrates, including fish, reptiles, birds, and humans and other mammals.It is the largest organ with respect to surface area of the vertebrate body

THE SKIN:THE SKIN: layers layersEpidermis

The outermost layer of epithelial tissue

DermisThicker than the epidermisMade up of a thick layer of connective tissue and one to several cells thickContains the blood vessels, nerves, glands and auxiliaries

HypodermisLayer below the epidermis made up of loose connective tissues and adipose tissues

SKIN OF JAWLESS FISHESSKIN OF JAWLESS FISHESThey have relatively thick skinOf the several types of epidermal glandular cells, one secretes the protective cuticleMulticellular slime glands secrete large amount of mucous to cover the body surface for protection

LAMPREY

HAGFISH

SKIN OF CARTILAGINOUS SKIN OF CARTILAGINOUS FISHESFISHESMultilayered and contains mucus and sensory cellsThe dermis contains bones in the form of placoid scales called denticles

COOKIE-CUTTER SHARK

MANTA RAYDenticles contain blood vessels and nerves and is very familiar to vertebrate teeth

SKIN OF bony FISHESSKIN OF bony FISHESBOWFIN

BROWN BULLHEAD

They contain scalesA thin layer of dermal tissue overlaid the superficial epidermis normally covers the scalesBecause scales are not shed, they grow at the margins and over the lower surfaceTheir skin are permeable and can be used in gas exchangeMucus are at help in fighting off bacterial and fungal infection at the surface

SKIN OF amphibiansSKIN OF amphibiansAmphibians are transitional between aquatic and terrestrial vertebratesConsists of stratified epidermis and a dermis containing mucus and serous glands plus pigmentation cellsThe earliest amphibians were covered by dermal bone scales

GREEN FROG

HELLBENDER

Their skin reflects their greater commitment to a terrestrial existenceThe outer layer of the epidermis (stratum corneum) is thick, lacks glands, and is modified into keratinized scales, scutes, plaques and beaksThe thick keratinized layer resists abrasion, inhibits dehydration and protects like a suit of armor

SKIN OF REPTILESSKIN OF REPTILES

ALLIGATOR

KING COBRA

SKIN OF BIRDSSKIN OF BIRDSOver most of the birds body, the epidermis is usually thin and only two or three layers thickThe most prominent part of the epidermis are the feathers (collectively known as plumage)Feathers are derived from the scales of reptilian ancestors and are, most complex of all derivatives of the vertebrate stratum corneum

BALD EAGLE

SKIN OF BIRDS:SKIN OF BIRDS: feathers feathers Feathers, provides the strong

yet lightweight surface area needed for powered, aerodynamic flight.

They also serve as insulation, trapping pockets of air to help birds conserve their body heat.

The varied patterns, colors, textures, and shapes of feathers help birds to signal their age, sex, social status, and species identity to one another.

Some birds have plumage that blends in with their surroundings to provide camouflage, helping these birds escape notice by their predators.

FISCHER’S LOVEBIRDS

AFRICAN JACANA

Mammalian skin’s notable features include:

Hair,A variety of epidermal glands than in other vertebrate class,A highly stratified cornified epidermis,And a dermis many times thicker than the epidermis

The prevention of dehydration is one of the evolutionary reasons mammals and other animals have been able to colonize terrestrial environment

SKIN OF MAMMALSSKIN OF MAMMALSENDAGERED SIBERIAN TIGER

HORSE (ARABIAN)

It forms a barrier that helps prevent harmful microorganisms and chemicals from entering the bodyIt also prevents the loss of life-sustaining body fluidsIt protects the vital structures inside the body from injury and potentially damaging ultraviolet rays of the sunThe skin also helps regulate body temperature, excretes some waste products, and is an important sensory organIt contains various types of specialized nerve cells responsible for the sense of touch

SKIN OF MAMMALS:SKIN OF MAMMALS: functions functions

The skin consists of an outer, protective layer (epidermis) and an inner, living layer (dermis) which contains blood vessels, lymphatic vessels nerve endings, hair follicles, small muscles and glands.The top layer of the epidermis is composed of dead cells containing keratin, the horny scleroprotein that also makes up hair and nails.

SKIN OF MAMMALS:SKIN OF MAMMALS: structures structures

Sudoriferous Glands (Sweat Glands)They secrete sweat by the process of perspiration which helps regulate body temperature and maintains homeostasis

Sebaceous Glands (Oil Glands)They are connected to the hair follicles in the dermisThey lubricate and protect the skin by secreting sebumSebum is a permeability barrier and emollient – defense against microorganisms and skin softening

SKIN OF MAMMALS:SKIN OF MAMMALS: glands glands

HairComposed of keratin filled cells that develop from the epidermis2 Parts:

SHAFT – portion of the hair that protrudes from the skinROOT – portion of the hair embedded beneath the skin

SKIN OF MAMMALS:SKIN OF MAMMALS: appendagesappendages

Arrector Pili MuscleAttaches to the connective tissue sheath of the hair follicle surrounding the bulb of the hair rootWhen the muscle contracts, it pulls the follicle and its hair to erect position (goosebumps)

SKIN OF MAMMALS:SKIN OF MAMMALS: appendagesappendages

NailsLike hair, nails are modification of the epidermisThey are flat horny plates on the dorsal surface of the distal segments of the digitsThey are made of dead cells containing the protein keratin

3 Parts:the concealed ROOTthe BODY, which is exposed but attached to skinand the EDGE

The nail grows out from the addition of new cells at the root