Anatomy & Physiology I: Skin and Body Membranes

Body Membranes

Multicellular sheets of epithelia and connective tissue.

Cutaneous Membrane

Skin; covers external body surfaces.

Body Membranes

Multicellular sheets of epithelia and connective tissue.

Cutaneous Membrane

Skin; covers external body surfaces.

Mucous Membrane

Lines open body cavities; moist surface.

Serous Membrane

Lines closed body cavities; reduces friction.

Parietal Serosa

Lining layer of serous membrane cavity.

Visceral Serosa

Covers organs within serous membrane cavity.

Epidermis

Superficial region of the skin.

Dermis

Middle region of the skin.

Hypodermis

Deepest region of the skin.

Keratinocytes

Produce keratin, a fibrous protein.

Melanocytes

Produce melanin, skin pigment.

Dendritic Cells

Macrophages activating the immune system.

Tactile Cells

Touch receptors in the skin.

Stratum Basale

Deepest epidermal layer; stem cells present.

Stratum Spinosum

Prickly layer with intermediate filaments.

Insensible Perspiration

Routine sweat loss; ~500 ml/day.

Sensible Perspiration

Increased sweating during elevated body temperature.

Acid Mantle

Low pH secretions retarding bacterial activity.

Biological Barriers

Dendritic cells and macrophages protect skin.

Blood Reservoir

Skin can hold up to 5% blood volume.

Excretion

Sweat contains nitrogenous wastes and salts.

Cutaneous Sensations

Includes temperature, touch, and pain perception.

Stratum granulosum

Thin layer with three to five flat cells.

Keratohyaline granules

Protein aggregates aiding in keratinization.

Stratum lucidum

Clear layer found only in thick skin.

Stratum corneum

Outer layer with 20-30 rows of dead cells.

Epidermal thickness

Stratum corneum accounts for three-quarters.

Skin protection

Prevents abrasion, penetration, and water loss.

Papillary layer

Upper dermis with areolar connective tissue.

Dermal papillae

Contain capillary loops and free nerve endings.

Reticular layer

80% of dermis, provides strength and resiliency.

Collagen fibers

Provide structural strength to the skin.

Elastic fibers

Allow skin to stretch and recoil.

Epidermal ridges

Form friction ridges for grip and fingerprints.

Cleavage lines

Collagen bundles dictate skin tension and healing.

Melanin

Pigment responsible for dark skin colors.

Carotene

Yellow-orange pigment visible in palms and soles.

Hemoglobin

Pigment giving skin a pinkish hue.

Cyanosis

Bluish skin due to poor oxygenation.

Sweat glands

Epidermal derivatives for thermoregulation.

Oil glands

Sebaceous glands that lubricate skin and hair.

Hair follicles

Structures from which hair grows.

Skin appendages

Derivatives of the epidermis including glands and hair.

Exocrine glands

Glands that secrete substances through ducts.

Sweat glands

Glands producing sweat for thermoregulation.

Apocrine glands

Sweat glands in axillary and anogenital areas.

Eccrine glands

Sweat glands abundant on palms and forehead.

Sebum

Oily secretion from sebaceous glands.

Ceruminous glands

Glands in ear canal secreting cerumen.

Mammary glands

Glands producing milk in females.

Sebaceous glands

Oil glands that secrete sebum.

Holocrine secretion

Entire cell disintegrates to release secretion.

Keratinized cells

Dead cells containing keratin for protection.

Melanins

Pigments responsible for hair color.

Basal Cell Carcinoma

Least malignant skin cancer, slow-growing.

Squamous Cell Carcinoma

Involves keratinocytes, more aggressive than basal.

Melanoma

Most dangerous skin cancer, involves melanocytes.

Nevus

A mole, small dark skin growth.

Dysplastic nevus

Atypical mole with potential to become cancerous.

ABCDE rule

Mnemonic for melanoma risk factors.

First degree burn

Epidermal damage with redness and pain.

Second degree burn

Epidermal and dermal damage with blisters.

Third degree burn

Full thickness skin damage, no pain initially.

Fluid loss estimation

Critical if >25% body has second degree burns.

Infection risk

Main threat after burns, post 24-36 hours.

Risk factors for skin cancer

UV exposure and frequent skin irritation.