CH 5

Flashcards covering the integumentary system, focusing on functional anatomy, skin components, and related clinical aspects, suitable for exam preparation.

Integumentary System

Skin or integument, the body's first line of defense, comprising 16% of body weight and spanning 1.5–2 m2.

Integumentary System Components

The two major components are the cutaneous membrane (epidermis and dermis) and accessory structures (hair, nails, glands).

Functions of the Integumentary System

Protects against impact, abrasion, fluid loss, and chemical attack; excretes wastes; maintains temperature; produces melanin and keratin; synthesizes vitamin D3; stores lipids; detects touch, pressure, pain, and temperature.

Epidermis

Composed of multiple cell layers (strata), primarily keratinocytes; deeper layers form epidermal ridges adjacent to dermal papillae for better attachment.

Thin Skin

Covers most of the body surface and contains four strata (layers).

Thick Skin

Found on palms and soles, contains five strata (layers).

Fingerprints

Unique patterns of epidermal ridges on fingertips, used for identification.

Stratum Basale

Attached to the basement membrane, contains basal cells (stem cells) and Merkel cells (touch receptors).

Stratum Spinosum

Composed of 8–10 layers of keratinocytes bound by desmosomes, contains dendritic (Langerhans) cells for immune response.

Stratum Granulosum

Composed of 3–5 layers of keratinocytes producing keratin and keratohyalin; cells become thinner and less permeable.

Stratum Lucidum

Found only in thick skin; separates stratum corneum from underlying layers; contains flattened, densely packed dead cells.

Stratum Corneum

Outermost protective region with 15–30 layers of keratinized cells; water-resistant but not waterproof; loses water through insensible and sensible perspiration.

Skin Pigments

Carotene (orange-yellow) and melanin (brown, yellow-brown, or black); melanin produced by melanocytes in stratum basale.

Hemoglobin

Red pigment in red blood cells; more blood flow results in a redder color, while less blood flow results in a pale or bluish (cyanosis) color.

Basal Cell Carcinoma

Most common form of skin cancer, originates in stratum basale due to UV radiation; low metastasis rate and high survival.

Malignant Melanoma

Dangerous skin cancer where cancerous melanocytes grow rapidly and metastasize; early detection has a high survival rate.

Dermis

Located between the epidermis and hypodermis, contains collagen and elastic fibers.

Papillary Layer

Contains dermal papillae, areolar tissue, capillaries, lymphatic vessels, and sensory neurons.

Reticular Layer

Interwoven meshwork of dense, irregular connective tissue with collagen and elastic fibers; contains blood vessels, lymphatic vessels, nerve fibers, and accessory organs.

Subcutaneous Layer (Hypodermis)

Not part of the skin, separates skin from deeper structures, dominated by adipose tissue for energy storage.

Sensory Receptors

Free nerve endings (touch and pressure), tactile corpuscles (texture and steady pressure), Meissner corpuscles (light touch), Pacinian corpuscles (deep pressure), and Ruffini corpuscles (skin stretching).

Tension (Cleavage) Lines

Arrangement of collagen and elastic fibers in the skin; cuts parallel to cleavage lines heal better.

Burns

Injuries from heat, friction, radiation, electrical shock, or chemicals that damage skin integrity.

First-Degree Burn

Only the surface of the epidermis is affected; example: sunburn.

Second-Degree Burn

Entire epidermis and possibly some of the dermis are damaged; blistering, pain, and swelling occur.

Third-Degree Burn

Destroys epidermis, dermis, and extends into subcutaneous layer; usually requires skin grafting.

Rule of Nines

Method of estimating the percentage of surface area affected by burns.

Emergency Treatment of Burns

Replacing fluids/electrolytes, providing nutrients, preventing infection, and assisting tissue repair with skin grafts.

Skin Grafts

Split-thickness (epidermis and superficial dermis), full-thickness (epidermis and both dermis layers); autograft (patient’s skin), allograft (cadaver skin), xenograft (animal skin).

Accessory Structures of Integument

Hair follicles, exocrine glands, and nails.

Hair Follicles

Produce hairs that protect the skull and provide touch sensations.

Exocrine Glands

Sweat glands (thermoregulation and waste excretion) and sebaceous glands (epidermis lubrication).

Nails

Protect and support tips of fingers and toes.

Terminal Hairs

Large, coarse, darkly pigmented hairs (scalp, armpit).

Vellus Hairs

Smaller, shorter, delicate hairs (general body surface).

Hair Shaft

Visible part of the hair above the skin surface.

Hair Root

Anchors the hair into the skin.

Root Hair Plexus

Sensory nerves surrounding the base of the hair follicle.

Arrector Pili

Smooth muscle attached to the hair follicle; contraction pulls hair erect (goosebumps).

Hair Bulb

Expanded base of hair follicle where hair formation begins.

Hair Matrix

Actively dividing basal cells in contact with hair papilla.

Medulla

Layer of daughter cells formed at the center of the matrix.

Cortex

Intermediate layer deep to the cuticle.

Cuticle

Daughter cells produced at the edges of the matrix; forms surface of the hair.

Hair Growth Cycle

Active phase (2–5 years) where hair grows and resting phase where hair is shed.

Sebaceous Glands

Holocrine glands that discharge an oily lipid secretion (sebum).

Sweat Glands

Watery secretion via merocrine secretion; myoepithelial cells squeeze the gland to discharge the secretion.

Apocrine Sweat Glands

Found in axillae, nipples, and pubic region; produce sticky, cloudy, odorous secretion.

Eccrine/Merocrine Sweat Glands

Secrete directly onto the skin surface; highest number on palms and soles; produce watery secretions for thermoregulation.

Nail Body

Visible portion of the nail.

Lateral Nail Folds

Covers nail bed (underlying epidermis).

Lunula

Pale crescent on the proximal part of the nail.

Free Edge

Distal part of nail body.

Nail Root

Epidermal fold where nail production occurs.

Eponychium

Portion of stratum corneum of nail root extending over the exposed nail (cuticle).

Hyponychium

Area of thickened stratum corneum under the free edge.

Age-Related Changes in Integument

Fewer melanocytes, drier/thinner epidermis, diminished immune response, thinner dermis, decreased perspiration, reduced blood supply, slower skin repair, fewer active follicles, altered hair and fat distribution.

Circulating Hormones Affecting Skin

Steroid and thyroid hormones, sex hormones, growth factors (EGF), and growth hormone (GH).

Sunlight and Vitamin D3

UV radiation converts epidermal cells to cholecalciferol (vitamin D3), which is converted to calcitriol, allowing calcium absorption.

Phases of Skin Regeneration

Inflammation, migration, proliferation, and scarring.

Inflammation Phase

Bleeding and mast cell activation cause swelling, redness, heat, and pain.

Migration Phase

Scab forms, stratum basale cells migrate, macrophages remove debris; granulation tissue forms if dermis is damaged.

Proliferation Phase

Epidermal cells migrate under scab, phagocytic activity completes, fibroblasts form collagen fibers and ground substance.

Scarring Phase

Scab sheds, scar tissue forms (inflexible, fibrous, noncellular).

Keloids

Raised, thickened mass of scar tissue that grows into the surrounding dermis.