Comparative anatomy( Chordates)

Integumentary system 1-Human 2-Ruminant 3-Avian 4-Fish5-Horse

Dr.Omer

Comparative anatomy (Chordates)

Human integumentary systemThe Integument

Is the largest system of the body

The integument is made up of two parts:

1. Cutaneous membrane

a. Epidermis– Superficial epithelium

b. Dermis – underlying CT with blood supply

2. Accessory structures

a. Hair

b. Nails

c. Exocrine Glands

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Functions of Skin1-Protection2-Prevention of water loss3-Temperature regulation4-Metabolic regulation5-Immune defense6-Sensory reception7-Excretion

STRUCTURE OF SKINThe layers of the skin:-

The Epidermis Epithelial tissue

Dermis Dense connective tissue proper – irregular

Hypodermis Subcutaneous tissue- loose connective tissue proper and

adipose tissue

STRUCTURE OF SKIN

Epidermis

Dermis

Hypodermis or

subcutaneous layer

Skin Structure: Epidermis

The Epidermis Is a vascular stratified squamous epithelium

Nutrients and oxygen diffuse from capillaries in the dermis

There are four or five layers of the epidermis, depending upon the

degree of friction and mechanical pressure applied to the skin

Four Principle Cells of the Epidermis • Keratinocytes Produce the protein keratin, which helps protect the skin and

underlying tissue from heat, microbes, and chemicals, and lamellar granules, which release a waterproof sealant

• Melanocytes Produce the pigment melanin which contributes to skin color

and absorbs damaging ultraviolet (UV) light• Langerhans cells – Derived from bone marrow– Participate in immune response

• Merkel cells – contact a sensory structure called a tactile (Merkel) disc and

function in the sensation of touch

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Skin Structure: Epidermis

Thin Skin

Covers most of the body

Has four layers of keratinocytes

Thick Skin

Covers the palms of the hands and soles of the feet

Has five layers of keratinocytes

Skin Structure: Epidermis

Structures of the Epidermis The five strata of keratinocytes in thick skin From basal lamina to free surface

1. Stratum basale2. Stratum spinosum3. Stratum granulosum4. Stratum lucidum5. Stratum corneum

Epidermal LayersStratum corneum - nuclei and organelles are destroyed by lysosomes

and the cells fill with keratin

Stratum lucidum - only found in the palms and soles of feet 3-5 layers of clear, flat, dead keratinocytes -Dense packed intermediate filaments thick plasma membranes

Stratum granulosum - cells start to become keritanized --Secretes lipid-rich secretion that acts as a water sealant

Stratum spinosum - 8-10 layers of keratinocytes skin both strength and flexibility

Stratum basale - Also referred to as stratum germinatum -where new cells are formed -

Thick skin LM 210

Surface

Stratumcorneum

Stratumlucidum

Stratumgranulosum

Stratumspinosum

Stratum basale

Basementmembrane

DermisPapillary layer of dermis

EPIDERMIS

Sources of Skin Color

• Most significant factor is melanin • Black or brown color due to eumelanin produced by melanocytes

and transferred to keratinocytes in follicle.

• Red color produced by pigment called pheomelanin

• Blonde color produced by intermediate levels of pheomelanin and low levels of eumelanin

• Other factors include hemoglobin (red to pink) and carotene (yellow)

• Different races have the same of melanocytes, but amount of melanin produced differs

• Melanin accumulates in keratinocytes

Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Skin Structure: Dermis

The Dermis Located between epidermis and

subcutaneous layer Anchors epidermal accessory

structures (hair follicles, sweat glands)

Two components1. Outer papillary layer 2. Deep reticular layer

Derm

is

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Skin Structure: Dermis The Papillary Layer

Consists of areolar tissueContains smaller capillaries, lymphatics, and sensory neuronsHas dermal papillae projecting between epidermal ridges

The Reticular LayerConsists of dense irregular connective tissueContains larger blood vessels, lymphatic vessels, and nerve fibersContains collagen and elastic fibersContains connective tissue proper

Hair

Papillarylayer

Reticularlayer

Cutaneousplexus

Papillaryplexus

Epidermalridges

Dermalpapillae

Capillary loopof papillary

plexus

DERMIS

Skin Structure: HypodermisThe Hypodermis (Subcutaneous Layer)

Lies below the integumentStabilizes the skinAllows separate movement Made of elastic areolar and adipose tissuesConnected to the reticular layer of integument by

connective tissue fibers

Skin Structure: Hypodermis

Hypodermis

Functions – Hair & Nails

• Functions of Hair – Hair on the head protects scalp from injury and sunlight– Eyelashes and eyebrows protect eyes– Nostril and ear hairs protect from foreign particles– Help in sensing light touch due to the touch receptors associated with the

hair root plexuses.• Functions of the Nails

– Grasping objects– Manipulating objects– Protects ends of digits from trauma– Scratching

Hair Anatomy Shaft: portion of hair that projects from skin surfaceRoot: portion of hair deep to the shaft penetrating the dermis

•Has 3 layers: medulla : Core, dead cells contain soft keratin and air to provide flexible

Cortex: Middle layer, dead cells contain hard keratin to provide stiffness

Cuticle : Outermost, overlapping dead keratinized cells form shiny surface

Base of the hair follicle•Bulb: houses the papilla which contains the blood vessels that nourishes the

growing hair follicle.•Matrix: responsible for hair growth and produces new hair Arrector pili: smooth muscle •Extends from the dermis to the side of hair follicle.Hair root plexus - dendrites of neurons which are sensitive to touch

Anatomy of the hair

Nails • Made of tightly packed, hard, keratinized epidermal cells• Consist of:

Nail body: portion of the nail that is visible- Free edge: part that exten

Nail root: the distal end of the digit portion buried in a fold of skinLunula: means little moon - Crescent shaped area of the nailHyponychium: secures the nail to the fingertip -Thickened stratum corneumEponychium or cuticle: narrow band of epidermis-Growth of nails is in the nail matrix.

Aging Skin •In our 20s, the effects of aging begin to be visible in the skin. •Stem cell activity declines: skin thin, repair difficult•Epidermal dendritic cells decrease: reduced immune response•Vitamin D3 production declines: calcium absorption declines and brittle bones•Glandular activity declines: skin dries, body can overheat•Blood supply to dermis declines: tend to feel cold•Hair follicles die or produce thinner hair•Dermis thins and becomes less elastic – wrinkles

Fish integumentary system Fish like other vertebrates have Three layers of skin1-Outer epidermis 2- Inner dermis.3-Hypodermis • Multicellular glands also occur in some fishes, e.g. electric organs of eels and electric rays, • luminescent glands in deep sea fishes. •Mucous glands are all unicellular. • Important modifications of skin are dermal scales that cover the body for protection.

Types of unicellular glands :

-Club cells - elongated, binucleated cells - secretes mucus

• Granular cells - secretes mucus in skin of lampreys & other fishes

• Goblet cells - narrowed base and wide apical end secretes mucus in chodrichthyes and osteichthyes

• Sacciform cells- secrete large, membrane-bound toxic products to repel enemies

Epidermis

• Generally the epiderm of vertebrates consists of

five layers• stratum corneum In fish keratin is replaced with

mucous ( glycoprotein = mucin)

Dermis

• Thicker than epidermis• Contains blood vessels, nerves, sense organs, connective tissue and

pigment cells Dermis consists of two layers 1- Upper looser layer - Stratum spongioso in this layer Scales are

imbeded with their bases2- Lower tighter layer Stratum compactum contains lipid cells and ‐

connective tissue• Fish dermis connects directly onto myosepta of the muscles and to

the caudal fin.

Colors of the skin

• Melanophores – Black• Erythrophores – Red• Xanthaphores – Yellow• Cyanophores – blue• Leucophores – light scattering• Iridiophores – light reflecting silver‐

Avian intgumentary system• Birds possess thin skin that is loosely attached to body to

allow free movement of wings during flight. • Feathers are characteristic modifications of bird skin, which

not only cover the entire body but also help in flight.

The skin is composed of three layers :1-The Epidermis2-The dermis or corium 3-The hypodermis

.

The fowl’s skin is divided into a number of separate areas

These areas are:• The feathered skin.• The scale covered skin on the lower legs and feet.• The hard, horny areas of the beak and toenails.• The pad of the foot (or plantar).• The skin of the comb and wattles • The areas where they do grow are called pterylae• The areas where they do not grow are called apteria.

Glands

• Birds do not possess sweat glands.• The uropygial gland secretes an oil (preen oil) bird will

typically transfer preen oil to its body during preening by rubbing its beak

• Feathers are an extremely efficient insulator.• Heat is lost from the respiratory tract and by radiation from

featherless surfaces. • The feet and legs of starlings loose a substantial amount of

the body’s heat.• Heat loss at night is also a probable reason for sleeping with

their head (really their beak) under their wing, and one leg raised.

cattle and Horse

• The skin of animals consists of three layers, • The epidermis • The dermis. • Hypodermis• Epidermis of thick keratinized stratified squamous epithelium• Special keratinized features include hair, nails, claws, horns,

hooves.• Numerous multicellular glands• Chromophores present

Hoofs and Horns

• True horns are made of keratin and are found in sheep, goats and cattle.

• They consist of a core of bone arising in the dermis of the skin and are fused with the skull.

• Hoofs are found in sheep, cows, horses .• These are animals that have lost toes in the process of

evolution and walk on the “nails” of the remaining toes.

• The hoof is a cylinder of horny ,material that surrounds and protects the tip of the toe

1. Heel bulb2. Periople at the heel3. Heel4. Quarter5. Toe6. Periople7. Coronary band