Bio 168 Chapter 5 Integument

Integumentary System

The organ system that consists of the skin and its derivatives

Skin

The cutaneous membrane that covers the external surface of the body

Sweat Glands

Glands that produce sweat to help regulate body temperature

Oil Glands

Glands that produce oil to lubricate the skin and hair

Hair

Flexible strands of dead, keratinized cells that grow from hair follicles

Nails

Scale-like modifications of the epidermis that protect the fingertips and toes

Epidermis

The outer layer of the skin composed of stratified squamous epithelium

Dermis

The inner layer of the skin composed of fibrous connective tissue

Subcutaneous Tissue

The layer deep to the dermis that anchors the skin to underlying organs

Keratinocytes

Most abundant cells in the epidermis. They contain the protein keratin and provide protection

Melanocytes

Cells in the epidermis that synthesize the pigment melanin and protect against UV light

Langerhans Cells

Star-shaped macrophages in the epidermis that ingest foreign invaders

Tactile Cells

Cells in the epidermal-dermal junction that function as sensory receptors for touch

Stratum Basale

The deepest layer of the epidermis where cells undergo mitosis

Stratum Spinosum

The layer of the epidermis where keratinocytes contain web-like intermediate pre-keratin filaments

Stratum Granulosum

The layer of the epidermis where cells accumulate cytoplasmic granules

Stratum Lucidum

The layer of the epidermis that is absent in thin skin and formed from dead cells

Stratum Corneum

The outermost layer of the epidermis that is filled with shingle-like dead cells

Papillary Layer

The upper dermal region composed of areolar connective tissue

Reticular Layer

The deepest skin layer composed of dense fibrous connective tissue

Friction Ridges

Projections on the skin that enhance gripping ability and contribute to the sense of touch

Cleavage Lines

Lines formed by collagen fibers in the skin that affect wound healing

Flexure Lines

Dermal folds at or near joints that cause deep creases

Melanin

The pigment produced by melanocytes that determines skin color

Carotene

An orange-yellow pigment from some vegetables that can accumulate in the skin

Hemoglobin

The red coloring from blood cells in dermal capillaries that can affect skin color

Skin Cancer

The abnormal growth of skin cells that can be caused by overexposure to UV radiation

Burns

Tissue damage caused by heat, electricity, radiation, or chemicals

What can alterations in skin color indicate?

Disease

What is cyanosis?

Blue skin color due to low oxygenation of hemoglobin

What is erythema?

Redness caused by fever, hypertension, inflammation, or allergy

What can pallor indicate?

Anemia, low blood pressure, fear, or anger

What is jaundice?

Yellow cast of skin due to liver disorders

What is bronzing?

Darkening of the skin due to inadequate steroid hormones

What are bruises?

Black-and-blue marks on the skin.

What causes bruises?

Clotted blood beneath the skin.

What are hairs (pili)?

Flexible strands of dead, keratinized epithelial cells.

What produces hairs?

Hair follicles.

What provides pigment for hair color?

Melanocytes.

What is the root of the hair?

The part of the hair enclosed by the follicle.

What is the shaft of the hair?

The part of the hair projecting from the skin or scalp.

What are the three parts of the hair shaft?

Medulla, cortex, and cuticle.

What is the medulla?

The central core of large cells and air spaces.

What is the cortex?

Several layers of flattened cells surrounding the medulla.

What is the cuticle?

The outer layer consisting of overlapping layers of single cells.

What determines the shape of the hair shaft?

The cross-section of the hair shaft.

What determines if hair is curly?

If the hair shaft is flat and ribbon-like in cross-section.

What determines if hair is wavy?

If the hair shaft is oval in cross-section.

What determines if hair is straight and coarse?

If the hair shaft is perfectly round in cross-section.

What is a hair follicle?

Connective tissue root sheath and epidermal root sheath that surround the hair root.

What is the arrector pili muscle?

A band of smooth muscle associated with each follicle that pulls hairs upright when cold or frightened (goosebumps).

What are nails?

Scale-like modifications of the epidermis.

What is the composition of nails?

Heavily keratinized with hard keratin.

What is the nail bed?

Deeper layers of the epidermis that extend beneath the nail.

What is the nail matrix?

Thickened, proximal portion of the nail bed responsible for nail growth.

What gives nails their color?

Lack of pigment makes them colorless.

What are the different parts of a nail?

Free edge, body or nail plate, proximal root, lunule, cuticle or eponychium.

What are sweat glands?

Glands that produce sweat.

Where are eccrine sweat glands found?

All over the body.

What is the structure of eccrine sweat glands?

Simple, coiled, tubular glands that open via a duct to a pore on the skin surface.

What is the composition of sweat produced by eccrine sweat glands?

Hypotonic filtrate of blood (sweat) that passes through secretory cells by exocytosis.

Where are apocrine sweat glands found?

Mainly in the axillary and groin area.

Where do apocrine sweat glands release their products?

Into hair follicles.

What is the composition of sweat produced by apocrine sweat glands?

Milky or yellowish substance, fatty acids, and proteins.

When are apocrine sweat glands activated?

At puberty.

What is the function of sweat?

Helps dissipate excess heat, excretes waste products, inhibits bacteria growth, and causes body odor due to associated bacteria.

What are ceruminous glands?

Modified apocrine glands found lining the external ear.

What do ceruminous glands secrete?

Cerumen or earwax.

What are mammary glands?

Modified sweat glands that secrete milk.

What do sebaceous glands produce?

Oil or sebum.

What are the functions of sebum?

Lubricates the skin, prevents brittle hair, and kills bacteria.

What happens to the cells of the alveoli in the integumentary system?

They accumulate oily lipids until they burst.

What are the appendages of the skin?

Hair, nails, sweat glands, and oil glands.

What are the three types of barriers in the integumentary system?

Chemical, physical/mechanical, and biological barriers.

What is the function of the chemical barrier in the integumentary system?

To retard bacterial activity and block penetration of certain substances.

What is the function of the physical/mechanical barrier in the integumentary system?

To block water, water-soluble substances, and lipid-soluble substances.

What is the function of the biological barrier in the integumentary system?

To protect against pathogens and absorb UV radiation.

How does the integumentary system regulate body temperature?

Through insensible perspiration, dilation of dermal vessels, and sweat gland activity.

What are the cutaneous sensations in the integumentary system?

Temperature, touch, and pain.

What are the receptors for soft touch in the integumentary system?

Tactile (Meissner's corpuscles).

What are the receptors for deep pressure in the integumentary system?

Lamellar (Pacinian corpuscles).

What are the metabolic functions of the integumentary system?

Conversion of cholesterol to Vitamin D precursor and blood reservoir.

How does the integumentary system excrete waste?

Through sweat, eliminating water, sodium chloride, urea, ammonia, and uric acid.

What is the risk factor for most skin tumors?

Overexposure to UV radiation.

What is skin cancer?

A disease characterized by the abnormal growth of skin cells

What are the three major types of skin cancer?

Basal cell carcinoma, squamous cell carcinoma, melanoma

What is basal cell carcinoma?

The least malignant and most common type of skin cancer

What are the characteristics of basal cell carcinoma?

Shiny, dome-shaped nodule with a central ulcer

How is basal cell carcinoma treated?

Surgical excision, which is successful in 99% of cases

What is squamous cell carcinoma?

A type of skin cancer that involves keratinocytes of the stratum spinosum

Where is squamous cell carcinoma most common?

On the scalp, ears, lower lip, and hands

What are the characteristics of squamous cell carcinoma?

Scaly, red papule

How is squamous cell carcinoma treated?

Radiation therapy or surgical removal

What is melanoma?

The most dangerous type of skin cancer

Melanoma

Involves melanocytes, highly metastatic and resistant to chemotherapy

Treatment for melanoma

Wide surgical excision accompanied by immunotherapy

Characteristics of melanoma (ABCDE rule)

Asymmetry, Border exhibits indentations, Color is black, brown, tan, and sometimes red or blue, Diameter is larger than 6 mm, Evolving or changing over time

Burns

Caused by heat, electricity, radiation, certain chemicals

Effects of burns

Tissue damage, denatured protein, cell death

Immediate threats of burns

Dehydration, electrolyte imbalance, renal shutdown, circulatory shock