Ch 09 The Integumentary System

Integumentary system

The skin and all its associated structures (hair, nails, glands).

Thermoregulation (skin)

How the skin regulates body temperature—by constricting or dilating blood vessels and evaporating sweat.

Three layers of the skin

Epidermis

• Outer layer of the skin

• Protects underlying structures, sheds its superficial cells, and renews them continually throughout life, and provides a waterproof barrier

Dermis

• Inner layer of the skin

• Composed of dense connective tissue with collagen fibers, which gives the skin strength and elasticity.

• It is well supplied with blood vessels and nerves.

• Contains the other skin organs: sweat glands, oil glands, hair follicles, and nail roots.

Subcutaneous layer

• Located below the other layers of skin

• Helps to anchor the skin to the underlying structures

• Within the subcutaneous fatty layer is a superficial fascia layer, which binds the skin to the parts beneath.

  • This layer guards against heat loss and provides insulation.

Skin color determinants

Determined primarily by a pigment called melanin and the underlying blood vessels.

Diagnostic site

A primary function of the skin where clinical signs (like color changes or lesions) can help identify systemic health issues or diseases.

Acne vulgaris

A common skin condition characterized by inflammation of the sebaceous glands, resulting in pimples, blackheads, and cysts.

Alopecia

The medical term for hair loss, which can be partial or complete.

Skin cancer

Abnormal growth of skin cells, typically triggered by UV radiation (includes basal cell, squamous cell, and melanoma).

Cellulitis

An acute, spreading bacterial infection of the deep layers of the skin and subcutaneous tissue.

Dermatitis

A general term for inflammation of the skin, often causing redness, swelling, and itching.

Eczema

A chronic, inflammatory skin condition characterized by itchy, red, dry, and scaly patches.

Folliculitis

An infection or inflammation of one or more hair follicles, usually caused by bacteria or fungi.

Furuncles and carbuncles

Boils caused by infected hair follicles; furuncles are single boils, while carbuncles are a cluster of interconnected boils.

Herpes (skin)

A viral infection causing painful, fluid-filled blisters on the skin or mucous membranes (e.g., herpes simplex).

Pediculosis

An infestation of lice, which can affect the head, body, or pubic region.

Poison ivy dermatitis

An allergic reaction causing an intensely itchy, blistering rash after contact with urushiol oil from the poison ivy plant.

Psoriasis

A chronic autoimmune condition that speeds up the life cycle of skin cells, leading to thick, silvery scales and itchy, dry patches.

Dermatophytosis - Ringworm (tinea corporis)

A highly contagious fungal infection of the skin or scalp, characterized by a ring-shaped rash.

Rosacea

A chronic inflammatory skin condition causing facial redness, prominent blood vessels, and sometimes pimple-like bumps.

Scabies

A contagious skin infestation caused by tiny, burrowing mites that result in severe itching and a pimple-like rash.

Urticaria

The medical term for hives—itchy, raised welts on the skin usually triggered by an allergic reaction.

Verrucae

The medical term for warts, which are benign skin growths caused by a viral infection (HPV).

Wrinkle treatments

Cosmetic procedures used to reduce fine lines and aging signs, including dermabrasion, chemical peels, and laser resurfacing.

Plastic surgery

A surgical specialty involving the restoration, reconstruction, or altering (reshaping) of physical features.

Melanocytes

Produce melanin that gives color to the skin

Sweat glands

Help lower body temperature

Blood vessels

The dilation and constriction of blood vessels regulate body temperature

Sebaceous glands

Produce sebum to lubricate the skin and inhibit the growth of bacteria on the skin

Abscess

A skin abscess occurs when a bacterial infection causes pus to collect in a localized area of the skin. Treatment involves draining the abscess and obtaining a culture to determine the causative pathogen.

Actinic keratosis (AK)

Very common, crusty skin lesion that results from years of sun exposure.

If left untreated, it may develop into skin cancer.

Either cryotherapy (liquid nitrogen) or a topical chemotherapy drug is used to destroy the lesion.

Herpes zoster (shingles)

a viral infection that causes a painful, blistering rash. It is caused by the reactivation of the varicella-zoster virus—the same virus that causes chickenpox. Anyone who has had chickenpox can develop shingles, usually appearing as a band on one side of the body.

Macule

A flat, distinct, and discolored area of skin that is usually less than one cm in diameter.

• A freckle is a macule.

Papule

Small, raised bump on the skin that is less than one cm in diameter.

• Insect bites and chickenpox are examples.
  

Pustule

A small elevation on the skin that exudates liquid.

• Also known as a pimple.
  

Scales

Flakes or dry patches of skin made up of excess dead epidermal cells. These are associated with psoriasis.

Verruca

Small, hard skin lesion caused by the human papillomavirus. Also known as a wart.

Vesicle

A small fluid-filled, blister -like lesion.

• A poison ivy rash consists of vesicles.
  

Wheal

A small bump that itches. Also known as a welt.

Pressure ulcer

(bedsores or decubitus ulcers) are localized skin and tissue injuries caused by prolonged, unrelieved pressure, friction, or shear.

They frequently develop over bony prominences (e.g., tailbone, heels, hips) in individuals with limited mobility, restricting blood flow and causing tissue damage

Erythema

Sunburn

Melanin

A complex biological pigment responsible for the natural color of human skin, hair, and eyes.

• Beyond pigmentation, it acts as a crucial photoprotectant by absorbing harmful ultraviolet (UV) radiation and neutralizing free radicals to prevent DNA damage in cells.

Pustule

A lesion with exudates

Pigment

Color

Sebaceous

Provides lubrication

Subcutaneous

A skin layer

Wheals

Raised, itchy, or stinging areas of skin that are often redder or paler than the surrounding skin.

• They are a classic sign of an allergic reaction, insect bite, or inflammatory response

Five Functions of the Skin

Protection, Perception, Temperature control, Absorption, Excretion

A common fingerprint pattern where the central papillary ridges make at least one complete circle or spiral

Whorl

Impetigo

a common, highly contagious bacterial skin infection, usually caused by Staphylococcus aureus or Streptococcus pyogenes

• A small red macule becomes a vesicle and then changes into a pustule with yellow crust and outer rim

Keloid

An overgrown, thick, and raised scar that extends beyond the borders of an original skin injury.

• Caused by an excess of collagen production during healing, they can be itchy, tender, or painful.

• They are common on the chest, shoulders, earlobes, and face, and frequently appear in individuals with darker skin tones.

The ABCDE Rules of Melanoma

Asymmetry

• One half does not match the other half.

Border irregularity

• The edges are ragged, notched, or blurred.

Color

• The pigment is not uniform. Shades of tan, brown, and black are present. Red, white, and blue may add to the mottled appearance.

Diameter

• It is greater than 6 millimeters. Any sudden or continuing increase in size is a sign.

Evolving

• The surface of a mole may change to be scaly, oozing, or bleeding. A bump may appear, pigment may spread, or redness/swelling/pain may occur.