STRUCTURES OF THE SKINHCT I

Layers of The Skin

Two primary layers

Epidemis

Dermis

Subcutaneous Tissue- A layer of loose connective tissue and fat that supports the epidermis and dermis.

Insulates the body

Stored source of energy

Shock absorbing pad

Epidermis

The outermost and thinnest primary layer of skin. Cells are arranged in distinct layers Thickness varies on the body.

Thinnest on the eyelids

Thickest on the palms and soles of the feet.

Stratum Germinativum- innermost layer where cells divide and push already formed cells to the surface. WHY IS CELL REGENERATION IMPORTANT?

Maintaining the skin barrier helps to defend against infection even with injuries.

Epidermis

Keratin- a tough waterproof protein that replaces a cells cytoplasm as they approach the surfaceProvides the outmost layer of skin with

abrasion-resistance and protective qualities.

Stratum Corneum- Outmost layer of keratin filled cells, made up of dead flat skin cells that shed every couple of weeks.

DO YOU KNOW WHAT MOST DUST IS MADE OF?

EPIDERMISPIGMENT CONTAINING LAYER- epidermal

layer that contains pigments called:MELANOCYTES ,(a specialized epidermal

cell) which produces a brown pigment called melaninAmount of melanin depends on

geneticsIncreased melanin= increased skin

colorSunlight can increase the amount of

melanin produced.

EPIDERMISDermal Epidermal

Junction-the area between the epidermis and dermis.

Break down of this junction can lead to blisters. Burns

Friction

Exposure to irritants (poison ivy)

Dermis Deeper and thicker layer of primary skin

layers

Composed largely of connective tissue

Dermal papillae-(upper layer)

Important part of the dermal epidermal junction helping to keep the skin layers together

Form groves and ridges unique to each individual.

Do you know what the ridges and groves are called?

FINGERPRINTS

Dermis

Deeper areas contain a network of collagen and elastic fibers

These elastic fibers decrease with age contributing to wrinkles

Dermis also contains Nerve endings

Sweat and sebaceous glands

Blood vessels

Muscle fibers

Hair follicles

Appendages of the skin HAIR

Born with hair all over our bodies. Newborn hair is called lanugo

Hair follicle- an epidermal tube-like structure required for hair growth

Shaft- visible part of the hair

Root= lies hidden in the follicle

Hair papilla- where hair growth begins

Hair bulb- at the base of the follicle (hair papilla is located here)

Arrector pili- specialized muscle that produces goose pimples

Receptors

Specialized nerve endings – makes it possible for skin to act as a sense organ

Meissner’s corpuscle- detects light tough

Pacinian corpuscle- capable of detecting pressure

SKIN GLANDS

TWO TYPESSweat (sudoriferous)

Sebaceous

Sweat or Sudoriferous Glands

Eccrine sweat glands-most numerous, important and wide spread.

Produce perspiration, which flows out through pores on the surface of the skin

Assist with body temperature regulation

Sweat or sudoriferous glands

Apocrine sweat glands

Found primarily in the axilla and genitalia

Secrete a thicker milky secretion

Breakdown of secretion by skin bacteria produces odor

WHEN DO APOCRINE SWEAT GLANDS ENLARGE AND START FUNCTION?

PUBERTY

Sebaceous glands Secrete oil or sebum for

hair and skin

Level of secretion increases during adolescence

Amount of secretion regulated by sex hormones

Sebum in sebaceous gland ducts may darken to form a blackhead

Acne vulgaris-inflammation of sebaceous gland ducts

Structure of the skin