PCB 3703 lecture 6 Integumentary System Structures and Disorders

What is the nail matrix?

Actively growing part of nail at proximal end of nail body.

What is the lunula?

Whitish semilunar area on proximal end of nail body.

What are nail folds?

Folds of skin overlapping the nail.

What is another name for the eponychium?

The cuticle.

What is the structural definition of the eponychium?

Narrow band of epidermis from margin of nail wall onto nail body.

What is the hyponychium?

Thickened stratum corneum over which free nail edge projects.

What is onychomycosis?

A fungal infection causing yellowish discoloration and hardened nail.

What characterizes yellow nail syndrome?

Nail growth at root slows or stops, leading to yellowish or greenish discoloration.

What causes spoon nail?

Iron deficiency.

What is the physical appearance of a spoon nail?

Nail body is concave rather than convex.

What do Beau's lines indicate?

Injury or chronic malnutrition.

Where is hair found on the human body?

Almost everywhere on the body.

How is a hair filament formed?

By keratinized cells growing from hair follicles.

What is lanugo?

Fine, unpigmented, downy hair that appears in the last trimester.

What is vellus hair?

Fine primary human hair found on upper and lower limbs.

What is terminal hair?

Coarser, pigmented, longer hair found on scalp, eyebrows, eyelashes, and men's beards.

What replaces vellus hair in axillary and pubic regions during puberty?

Terminal hair.

What are the three zones along the length of a hair?

Hair bulb, root, and shaft.

What is the hair bulb?

Swelling at base where hair originates in the dermis.

What structure does the hair bulb surround?

The hair papilla, which is composed of connective tissue.

Which hair region contains living epithelial cells?

The hair bulb.

What is the hair root?

Zone of hair from bulb to skin surface.

What is the hair shaft?

Portion of hair beyond skin surface.

What is the hair matrix?

Structure at the base of the hair bulb where epithelial cells divide.

What is the medulla of a hair?

Remnant of matrix composed of flexible, soft keratin.

What is the cortex of a hair?

Flattened cells closer to outer hair surface that are relatively hard.

What is the hair cuticle?

A single cell layer around the cortex.

What is a hair follicle?

Tube surrounding hair root that extends into dermis and sometimes subcutaneous layer.

What is the arrector pili?

Thin ribbons of smooth muscle extending from hair follicle to dermal papillae.

What causes goosebumps?

Contraction of the arrector pili elevating the hair.

What are the functions of hair?

Protection, heat retention, sensory reception, and visual identification.

How does hair provide sensory reception?

Root hair plexuses detect light touch.

How is hair color determined?

Synthesis of melanin in matrix adjacent to hair papillae.

What causes gray hair?

Gradual reduction in melanin production.

What causes white hair?

Complete stoppage of melanin production.

What are the three phases of the hair growth cycle?

Anagen, catagen, and telogen.

What occurs during the anagen phase?

Active growth phase.

What occurs during the catagen phase?

Brief regression period where cell division stops.

What occurs during the telogen phase?

Resting phase when hair is usually shed.

How many hairs are normally lost per day?

10 to 100 hairs.

What is alopecia areata?

Circular bald patches resulting from an immune disorder recognizing hair follicles as foreign.

What is diffuse hair loss?

Shedding from all parts of the body.

What causes male pattern baldness?

Genetics and testosterone, replacing terminal scalp hairs with vellus hairs.

What is hirsutism?

Development of terminal hairs on atypical body parts due to male sex hormones or medical conditions.

What are the two main types of exocrine glands in the skin?

Sweat glands and sebaceous glands.

What cells aid in the secretion process of sweat glands?

Myoepithelial cells.

Where does a sweat gland duct open?

To a sweat pore.

What are merocrine sweat glands?

Most numerous, simple coiled tubular glands that discharge sweat via exocytosis.

What is the composition of merocrine sweat?

99% water and 1% other chemicals including electrolytes, metabolites, and waste products.

What is the major role of merocrine sweat glands?

Thermoregulation.

Where do apocrine sweat glands discharge secretions?

Into hair follicles located in axillae, around nipples, and pubic and anal regions.

What do apocrine sweat glands produce?

Viscous, cloudy secretions containing proteins and lipids that produce odor when acted on by bacteria.

When do apocrine sweat glands start producing secretions?

During puberty.

What type of glands are sebaceous glands?

Holocrine glands.

What do sebaceous glands produce?

Oily secretion called sebum.

What are the functions of sebum?

Acts as a lubricant for skin and hair and provides bactericidal properties.

Where do sebaceous glands discharge their secretion?

Into a hair follicle.

What stimulates sebaceous gland secretion?

Hormones, especially male sex hormones during puberty.

What is a comedo?

A sebaceous gland plugged by sebum.

What are pustules?

Dome-shaped acne lesions filled with pus.

What is a nodule in acne?

Deeper pustules that usually rupture the hair follicle.

What is a cyst in acne?

Larger nodule that is severely inflamed and prone to scarring.

What are ceruminous glands?

Modified apocrine sweat glands located in the external ear canal.

What do ceruminous glands produce?

Waterproof earwax called cerumen.

What are mammary glands?

Modified apocrine sweat glands of the breast that function in pregnant and lactating females to produce milk.

How does repetitive mechanical stress affect the integumentary system?

Stimulates cell division, resulting in thicker skin that withstands more stress.

What are the two ways tissue is repaired?

Regeneration or fibrosis.

What is regeneration in tissue repair?

Replacement of damaged or dead cells with the same cell type, restoring organ function.

What is fibrosis in tissue repair?

Filling gaps with scar tissue (collagen produced by fibroblasts) without restoring functional activities.

What is the first stage of wound healing?

Cut blood vessels bleed into the wound.

What happens during the second stage of wound healing?

Blood clot forms and leukocytes clean wound, providing a temporary barrier.

What happens during the third stage of wound healing?

Blood vessels re-grow and granulation tissue forms.

What happens during the fourth stage of wound healing?

Epithelium regenerates and connective tissue fibrosis occurs.

What causes burns?

Heat, radiation, chemicals, sunlight, and electrical shock.

What are the main life threats from severe burns?

Fluid loss, infection, and effects of burned tissue.

What layers are involved in a first-degree burn?

Only the epidermis.

What are the symptoms of a first-degree burn?

Slight redness and pain.

What layers are involved in a second-degree burn?

Epidermis and part of the dermis.

What are the symptoms of a second-degree burn?

Skin blistered and painful.

What layers are involved in a third-degree burn?

Epidermis, dermis, and subcutaneous layer.

What treatments are required for third-degree burns?

Hospitalization, fluid/infection management, debridement, and skin grafts.

What method is used to measure burn surface area?

The rule of nines.

When are burns considered critical?

When >25% has second-degree burns, >10% has third-degree burns, or third-degree burns are on hands, feet, face, or perineum.

How does aging affect skin stem cells?

Reduced number and activity of stem cells slow skin repair processes.

What structural fiber changes occur in aging skin?

Fewer collagen fibers and elastic fibers lose elasticity, forming wrinkles.

Why does immune response decrease in aging skin?

Due to a reduced number of dendritic cells.

How does smoking and UV radiation affect skin cells?

Damages DNA in epidermal cells, accelerates aging, and promotes skin cancer.

What is basal cell carcinoma?

The most common and least dangerous skin cancer originating in the stratum basale.

What is squamous cell carcinoma?

Skin cancer that arises from keratinocytes of the stratum spinosum and may metastasize.

What is malignant melanoma?

The most deadly and aggressive skin cancer arising from melanocytes, usually from a pre-existing mole.

What is the role of myoepithelial cells in sweat glands?

They aid in the secretion process.

What is the origin of the outer connective tissue root sheath of a hair follicle?

It originates in the dermis.

What is the origin of the inner epithelial tissue root sheath of a hair follicle?

It originates from the epidermis.

Between which two structures do the arrector pili muscles extend?

From the hair follicle to the dermal papillae.

What is the immediate first-aid treatment for a first-degree burn?

Immerse the burned area in cool water.

Why should ointments be avoided when treating second-degree burns?

Because ointments lead to heat retention.

Why do patients with third-degree burns require additional caloric intake?

To support severe tissue healing and recovery demands.

What are the four primary management steps for burn treatment?

Manage fluid loss, manage pain, remove dead tissue, and control infection.

What are the two primary functions of cerumen produced by ceruminous glands?

Traps foreign material and lubricates the acoustic meatus and eardrum.

What physical characteristics of a mole indicate potential malignant melanoma?

Changes in mole diameter, color, shape of border, and symmetry.