THE INTEGUMENTARY SYSTEM

Skin and its Derivatives

DERMATOLOGYSTUDY OF THE STRUCTURE,

COMPOSITION, AND FUNCTIONS OF THE SKIN

DERMA- SKIN

SKIN/INTEGUMENT – the largest organ of the body, approximately 5 kg of the body weight

thick in palms and soles, thin in eyelids and scrotum

Functions of SkinProtects from injuriesActs as barrier and regulates what

enters/leaves body.Regulates body temperature.Synthesizes, stores vitamins.Sensory functionsExcretionAbsorption

Main layers of the Skin1. Epidermis – outermost skin layer

2.Dermis – true skin layer

3. Hypodermis – the subcutaneous layer

DIFFERENCES OF THE SKIN LAYERSBASIS EPIDERMIS DERMIS HYPODERMIS

1. LOCATION OUTERMOST SUB EPIDERMAL SUBCUTANEOUS

2.THICKNESS THIN THICK RELATIVE

3. HISTOLOGICAL COMPONENT

HIGHLY EPITHELIAL CONNECTIVE, MUSCULAR,NERVOUS,VASCULAR

CONNECTIVE

4. VASCULARI- ZATION

AVASCULAR VASCULAR VASCULAR

5. LAYERS 5 SUB LAYERS

1.S. CORNEUM2.S. LUCIDUM3.S. GRAULOSUM4. S. SPINOSUM5. S. GERMINATIVUM

2 SUB LAYERS

1.S. PAPILLAROSUM

2.S. RETICULAROSUM

RELATIVE

6. NERVE ENDINGS ABSENT PRESENT PRESENT

7. GLANDS AGLANDULAR GLANDULAR –SWEAT,SEBACEOUS,MAMMARY

GLANDULAR – SECRETES LEPTIN

8. DERIVATIVES HAIRS AND NAILS GLANDS GLAND

EPIDERMAL DIFFERENCES

I.Epidermis of fishes and Aquatic amphibians

GLANDS1.MUCOUS GLANDSsecretes gelatinous substance mucinin frogs; for water absorption and

respirationin fish; defense mechanism for predations

2.SEROUS GLANDS-secretes poisonous alkaloids for protection against predators.

3.PHOTOPHORES GLANDS-contains light-emittingn

II.EPIDERMIS OF TERRESRIAL OR LAND VERTERATES

GLANDS1.MAMMARY GLANDSsecretes milk-feed the youngboth sexes;male-non functional;female-

location

2.SWEAT GLANDS AND SUDORIFEROUS GLANDS

produce sweat/perspiration cooling mechanism to regulate body temp

3.OIL/ SEBACEOUS GLANDSsecretes oilo/sebum;for lubrication/mare skin moist/shiny

4.UROPYGIAL GLAND [BIRDS]tail of uroryogiumsecretes oil,oiling the beark;shiny feathers/preening by beaks

5.SEROUS GLANDS [SNAKE]secretes poison/toxic alkaloids

6.CERUMINOUS GLANDS [MAN]-secretes cerumen

7.GLANDS OF ZELS-moits the eyelashes

8.MELBOMIAN GLANDS-moists the eyelids

TYPES OF GLANDS ACCDG. TO MANNER OF SECRETION1.MEROCRINE GLANDS [TRUE GLAND]release secretion thought

memrbrane/cells remain intact.ex.unicellular integumentary glands sweat

glands2.HOLOCRINE GLANDScells themselves constitute the secretioncells goes with secretionex.sebaceous gland

APOCRINE SWEAT GLAND

3.APOCRINE GLANDSintermediate in positionsecretions gathers at the tip or apical portion of the cell

part of the cyptoplasm are pinched off with the secretion & then repair itself.

ex.mammary glands

EPIDERMAL DERIVATIVES

1.MAMMALSHAIR- shaft,bulb,rootNAILS-lunula,nail bed,rootCLAWS-cats,monkeys,bird,etc,HOOVES-ungulatesTUSKS-elephants,source of plastics

2.BIRDS-BEAKS,PREENING,NESTING,F00D-FEATHERS-FOR INSULTION,FLIGHTS,BODY CONTOURS

parts;shaft,barbs,barbules,,calamusTypes;1.flight feathers2.covert feathers3.pin feathers4.filoplumers5.hair feathers

3.REPTILESepidermal scales-moltingExoskeleton turtles-scutes -corapace - plastron

4.AMPHIBIAN-rough/coarse skin

5.FISHES –with dermal scales

Types of scales1.CYCLOID SCALES-concentric ridges-milkfish2.CTENOID SCALES-w/spines or ctenii3.GANIOD SCALES-rhomboid shape,4.COMOID SCALES-extinct fishes dermal armor5.PLACOID SCALES-spines directed caudally-sharks,skates

COMPARATIVE ANATOMY OF THE SKINCHORDATE EPIDERMIS DERMIS

1. AGNATHANS ‘multi-layered and is rich w/mucous glands

‘slime eels lack scales

‘Layers are mitotic including surface cells horny denticles in the buccal funnel is the only cormfied structure,shed replaced

‘thinner than epidermis but tough due to interwoven collagenous fibers.

‘rich in the melanophores w/c ad heres tightly to the underlying musculator myosepta

CHORDATE EPIDERMIS DERMIS

2.CHONDRICH-THYES

‘more layered and cells are compactly arranged

‘unicellular glands excepting chaemiras

‘stingrays-goblet toxins.

‘multicellular cells at the base secretes toxins

Multicelullar cells are conc. at the base of the claspers of males

‘thicker than epidermis and w/2 more or less defined layers

‘placoid scales fr.the paleozioc shakers

‘sheet of melanophores derse dorsally than virtrally less illumnuscence

‘with ceratotrichia or fin rays

CHORDATE EPIDERMIS DERMIS

3. OSTEICH-THYES

-more mucous glands

-presence of cycloid scales

-with uicellular goblet cells w/c maintain mucous coat of the skin to prevent dessication

-with poisonous granular gland

-photophores serve as lures /warning

-presence of ancient ganoid or modern cycloid scale

-flexible dermal fin rays which stregthens the fins of bony fishes

-with osteoderms

Bony fish

CHORDATE EPIDERMIS DERMIS

4.AMPHIBIA ‘skin-w/o scales

‘with incipient stratum corneum

‘uncellular goblet cells secretes mucigens for semi-aquatic amphibians

‘mucons glands-mucin

‘poison glands-alkaloidal secreation

‘cornified skin prevents dessication.

‘with dermal chomatophores

‘firmly attached to the underlying musuculature

‘voluminous bread subcutaneous lymph sinuses separates skin from muscles

‘bony dermal scales in caecilians

CHORDATE EPIDERMIS DERMIS

5.REPTILES ‘thick stratum corneum

‘with epidermal scales molts at regular internal

‘presence of unique horny surface features

‘integumentary glands are not abundant

‘scales,scutes,rattles,clansz,plaque,spiny crests

‘bony dermal,bones are more abundant

‘osteoderms

1.lizards-underlying the

epidermal scales

2.snakes-absent

Reptilian

CHORDATE EPIDERMIS DERMIS

6.AVES ‘thin-skinned

‘epidermal scales umited to feet and base of breaks

‘presence of sharp clans

‘integumentary glands are absent

‘uropygial gland caudal, oil the feathers

‘with feathers

.down

.filoplumes

.rectrices

.remiges

‘dermis supports the feathers and arrectures pilorum/ plumarun

‘exceptionally thin

‘motility of skin is correlated to thermoregulatory function of feathers

‘no osteoderms

‘with spurs both sexes

.tarsometatasus

.carpometasus in some

CHORDATE EPIDERMIS DERMIS

7.MAMMALS ‘hairs are present arising from hair follicles

‘epidermal glands

.sebaceous-sebum

.sudoriferous-sweat

.mammary-milk

‘stratum germinativum is germinating

‘dense stratum corneum

‘derivatives

.claws

.horns

.hairs

.nails

.baleen whale bone

hangs or oral cavity

‘presence of hair follicle,arrector muscles,sweat,

sebaceous glands,conn. tissues

‘highly vascularized

‘with nerve endings

‘has thermoregulatory function-homiothermic

‘hypodermis or subcutaneous layer separates skin from muscles

‘with pigment cells

THE MAMMALIAN SKIN

Stratum corneum

Stratum granulosumStratum spinosum

Stratum basale (germinativum)

Stratum lucidum**

**Thick skin only

Stratum BasaleLowest epidermal layer, near dermisGood nutrient supplyReproduces by mitosisCuboidal, columnar in shapeMoves to upper epidermis in 27 days.

Stratum SpinosumLiving cellsDividing8-10 cells thickPolygonal in appearance

Stratus Granulosum, Lucidum Poor nutrient

supply.Flatten layer of

cells.3-5 cells thick.No cell division.Keratin

accumulates.

Found only in very thick skin.

Translucent.Highly keratinized.Dead cells

Stratum Corneum25-30 cells thick.Cells are filled with keratin and hardened.Sloughed off.Outer most layer of epidermis.Keratinocytes

MelanocyteProduces melanin

for protection from UV radiation.

Responsible for skin color.

Melanoma.

Melanocyte

                                                                

Irregular Dense Connective TissueCollagenous fibers

Layers of the dermis1. Stratum papillarosum

- superficial region(1/5) of the dermis,consists of areolar connective tissues with elastic fibers- contains dermal papillae that house capillaries,touch corpuscles,& free nerve endings

2. Stratum reticularosum- the deeper portion (4/5 of the dermis)- with dense regular conn. Tissue with bundles of collagen and elastic fibers- spaces between fibers contain adipocytes,hair follicles,nerves,sebaceous glands, sudoriferous glands

Sweat glandSebaceous glandArrector pili muscleBlood vessels

FEATURE THIN SKIN THICK SKIN

1. Distribution All parts of the body except palms,palmar digits,soles

Palms,palmar surface of digits and soles

2. Epidermal thickness 0.10-0.15mm 0.6 – 4.5 mm

3. Epidermal Strata Lack stratum lucidum,thinner s. spinosum and s. corneum

Thick s. lucidum,spinosum,corneum

4. epidermal Ridges Lacking due to poorly developed or fewer dermal papillae

Present due to well- developed or numerous dermal papillae

5. Hair follicles and Arrector pili Muscle

Present Absent 

6. Sebaceous Glands Present Absent 

7. Sudoriferpous Gland Fewer More numerous

8. Sensory Receptors Sparser denser

DERIVATIVES OF THE EPIDERMIS1. HAIR

PARTS OF HAIRA. HAIR ROOT D. HAIR FOLLICLE

B. HAIR SHAFT E. HAIR CORTEX

C. HAIR BULB F. HAIR MEDULLA

Hair Follicle

TYPES OF HAIRA. ANGORAB. DEFINITIVE HAIRC. LANUGO

2. NAILA. NAIL ROOTB. NAIL BEDC. LUNULA

Angora Hair

Definitive Hair

Lanugo Hair

Sebaceous Gland

DERIVATIVES OF THE DERMIS

Sweat GlandSKIN GLANDS

Types of Sweat Glands(Sudoriferous Glands)Merocrine glands: release fluid by

exocytosisEccrine

Most commonSecretion is mostly water with solutesCools body down

ApocrineDevelops scent as bacteria metabolize

secretionStimulated when frightened, during pain,

during emotional upset

APOCRINE SWEAT GLAND

ECCRINE SWEAT GLAND

Sensory Structures of DermisDeep touch/pressure: Pacinian corpuscles

Light touch/pressure: Meisner’s corpuscles

Warm temperature: Free nerve endings

Cold temperature: Free nerve endings

Pain: Free nerve endings

Recognized by adipose tissue.

FACTORS INFLUENCING SKIN COLOR1. GENETIC INFORMATION2. AMOUNT OF MELANIN PIGMENTS3. DEGREE OF OXYGENATION4. HORMONES

* MSH5. EXPOSURE TO SUNLIGHT

WHITE SKIN

BROWN SKIN