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DN4

Dr Viv Rolfe

SKIN STRUCTURETake 5 minutes to chat through the structures

of the skin.

EPIDERMIS

DERMIS

SUBCUTANEOUSLAYER

3 main layers Hair shaft

Sweat gland

ArrectoresPilorum

Hairfollicle

Sebaceousgland

melanocyte

Sweat glandExcretion of salts/waterThermoregulation

Sebaceous glandSecretion of sebumProtective film waterproofs skinKeeps hair softAntibacterial

HairEye, ear & nasal hair protects from particlesScalp hair protects from suns rays

Hairs provide insulation therefore are involved in thermoregulation

Hair follicleProduces new hairHair shaft for insulation

Arretores pilorumMuscle contracts to make hair erectImportant for thermoregulation and also occurs during fear

In the ear.They help form wax, and along with hair prevents the

entrance of foreign bodies.

Where are the ceruminous glands?

SKIN FUNCTION

• Stratum corneum – dead cells

• Stratum lucidium

• S granulosum

• S spinosum

• S basale - mitosis

1 Protection

What makes the skin an effective barrier?

Discuss for 5 minutes.

Barrier

Epidermis cells form a barrier of keratin-filled cells(waterproofing)

Cells are continually sheding and renewing

Sebum contains anti-microbials

Hairs are protective (e.g. eye lashes and nasal hairs)

How does the skin tan?

Discuss for 5 minutes.

EPIDERMIS

DERMIS

Tanning

MELANOCYTES

The tanning process

UV light stimulates enzymes that produce melanin

Melanocytes change shape and send out longprocesses into the tissue

Epidermal cells take up melanin from the processes

The skin darkens and protectsfrom UV damage by reducing light absorption

Albinism -congenital absence of pigment in skin, hair and eyes.

Vitiligo -absence of pigment producing white patches.

Conditions relating to skin colour

Age 27 Age 41

Vitiligo – patches where melanin is absent

2 Thermoregulation

37o

HOT!

Skin thermoreceptors

Message to brain “ITS HOT”

Nerve impulse to sweat glandto perspire and blood

vessels to widen (dilate)

Heat is lost as sweat evaporates,and from vessels by convection

Skin thermoreceptors

Message to brain “ITS COLD”

Nerve impulse to ARRECTOR PILARIS muscle to contract

Hairs stand on end to giveinsulation

Blood vessels shrink (contract)to minimise heat loss

•Body temperature above 40oC

•Body temperature severely reduced,becoming dangerous below 37 oC

Hyperthermiaor

Pyrexia

Hypothermia

3 Vitamin D synthesis

What does vitamin D do in the body?

How is deficiency caused?

What are the consequences?

How could it be prevented?

Sunlight produces pro vitamin D in the skin

This is transported to the liver and kidney, and active vitamin D is formed.

How is it made?

What does it do?

•Vitamin D is involved in calcium balance •It works with the hormone parathyrin to

•BOOST Ca++ when blood levels are LOW

Vitamin D deficiency

What does it cause?Rickets

How could it occur?At high altitude or cold climates where the skin is covered

in clothing. In polluted areas where UV rays can’t break through.

How can we prevent it?Fish, eggs, liver rich in vitamin D

Sunbathing

Skin as a sensory organ

Skin receptors

Monitor changes in

temperaturepressure

pain