Integumentary System

Skin

Hair

Nails

and associated glands

Cutaneous = skin

Skin is the largest organ of the body

17,000 sq cm –average adultFunction:• Protection -prevent vs

dehydration,microbes,UV radiation, physical insult

• Regulate Temperature• Vitamin D synthesis• Information about environment – extension

of the nervous system

Skin has 3 distinct sections

• Epidermis = layers of stratified squamous epithelial tissue

• Dermis = loose connective tissue

• Hypodermis [subcutaneous] - adipose tissue

Subcutaneous tissue anchors skin to the underlying tissue/organs

1/2 of the body’s adipose tissue

‘storage adipose’ = energy adipose

also contributes to cushioning and temperature control

aging/maturation = distribution of fat stores changes

“baby fat” over whole body

male - neck, lower back ‘love handles’

female - breast,hips/thighs

abdomen

Epidermis

Epidermis – The outer most layer composed of epithelial cells. It is subdivided in to thin layers called strata and contains no blood vessels

Epidermis has 5 distinct layers of cells

stratum basale - one layer of cells

stratum spinosum - 8-10 layers of cells

stratum granulosum - 2-5 layers of cells

stratum lucidum - several layers of cells

stratum corneum - 25 + layers of cells

Specialized cells in epidermis

Melanocytes - produce melanin - pigment--- 25% of basal cells

Keratinocytes - produce a protein mixture of keratin

Langerhans cells - phagocyte

Merkel’s cells - specialized cells associated with nerve endings -detect light touch and pressure

melanocyte

Stratum Corneum

The stratum corneum is the outer most stratum of the epidermis.

It is comprised of flat, tough, keratin containing cells that provide a protective layer for the skin.

Keratin is a protein that strengthens the cells and is also found in other areas of the body.

The cells in this stratum are either dead or dying, as they have no blood vessels to keep them alive.

Stratum granulosum

Stratum lucidum

Stratum corneum

Highly pigmented skin

keratinocytes

DermisAlso called the “true skin.”

Is a network of elastic connective tissue that contains blood vessels and nerves, as well as the appendages of the skin.

Extensions of the dermis, known as papillae, extend toward the epidermis and form what we know as fingerprints.

Dermis has two distinct regions

Papillary region: top area loose connective tissue with high % of elastin fibers

folds called dermal papillae - ridges for friction/gripping

fingerprints

Reticular region:connective tissue with collagen and elastin fibers stretch -return to original shape

Papillary region

Structures in DermisBlood vessels

hair follicles

sebaceous glands

sweat glands [sudoriferous glands]

merocrine - help regulate temperature

eccrine - don’t regulate temperature -odor

arrector pili muscle

Nerve endings – pain, temperature, touch, vibration

other glands: ceruminous glands [modified merocrine]

Sweat GlandsThe technical name for sweat glands is sudoriferous glands.

Sudoriferous glands help regulate body temperature through the evaporation of sweat.

Secretions of the sweat glands in the groin and armpits also contain cellular debris that produce body odor when broken down by bacteria.

Sebaceous GlandsProduce sebum, an oily substance that prevents drying of the skin and hair.

Blackheads are blocked sebaceous glands full of dried sebum and keratin.

Pimples are infected blackheads.

Sebaceous cysts may form over time if the glands stays blocked and will continue to increase in size. (until they’re dealt with)

Hair is composed primarily of keratin and covers most of the body.

The hair grows from the follicle, a sheath in the dermis.

Most follicles have a small muscle associated with it, which allows it to raise forming “goose bumps.”

Factoid: eye lashes protect eyes, but also sense when something is coming towards the eye. Grow new eyelashes every 5 weeks.

HAIR

shaft : part above skin surface

root: part below skin surface

Nails – extensions of the epidermis

Protective & functional

The larger the digit, the faster the nail grows

NailsNails are made of hard, keratinized cells and provide protection to the fingers and toes.

New cells form continuously in the nail root at the proximal end of the nail.

PigmentThe color of the skin is controlled by the amount of melanin in the skin.

As melanin helps protect the skin from UV rays, the amount of melanin increases with sun exposure.

DiscolorationsPallor – often decreased blood flow or anemia.

Flushing – increased blood flow, often related to exercise,fever, or infection.

Cyanosis – blueing of the skin due to decreased oxygenation of the blood.

Jaundice – yellowing of the skin from increased bilirubin in the blood often associated with liver disease and hemolytic disease.

Carotenemia – excessive intake of carotene containing vegetables, like carrots, leading to an orange cast to the skin.

Bronzing/ gray/ brown discolorations – Addison’s disease, chronic poisonings

Lesions are essentially any damage to tissue.

Size, shape, height, and/or depth of the lesion are all important aspects in evaluating a skin lesion.

Surface LesionsRash – an area of erythema (redness) of the skin.

Eruption – a raised rash, often erythematous.

Macules – flat spots, such as in measles and freckles.

Surface Lesions Papules – firm, raised areas, such as in chickenpox or pimplesNodules – Large papulesVesicles – blisters full of fluid, such as in poison ivyPustules – infected vesicles filled with pus, such as in folliculitis

Papules from scabies

Nodule from Basal Cell Carcinoma of Scalp

Herpes simplex induced vesicles

Pustules induced by a Group A beta-hemolytic streptococcal infection

Deeper LesionsExcoriation – scratches, often associated with intense itching or a psychological disturbanceLaceration – a rough, jagged wound from tearing, more than cutting Ulcer – from death of tissue, such as with diabetic and tropical ulcersFissure – a crack in the skin, such as in athlete’s foot.

Excoriations from Swimmer’s Itch

Fissure

Effects of Aging on the Integumentary System

•Thinning of the dermis•Decreased elasticity•Wrinkling due to decreased collagen and fat•Thinning, drying, whitening of the hair – by 50 yrs of age, most people will start ‘graying’•Decreased perspiration•Nail growth slows•Decreased blood flow will upset temperature regulation

Common Terms to be familiar with

• Dermatosis and Dermatitis

• Dermatosis is any skin disorder.

• Dermatitis is an inflammation of the skin which can have a large variety of causes.

Contact Dermatitis from metal

Contact Dermatitis from Adhesive

Alopecia is the technical term for baldness

Aside from hereditary male pattern baldness, alopecia can be caused by:

MalnutritionChemotherapySystemic diseaseIt can also be idiopathic

Approx. 50%of male population will have some degree of balding with increased age

B D Tyagi of Bhopal in India The hair growing from the middle of his ears measures an astonishing 10.2cm at its longest point, which is probably long enough for small pony tails.