3M: Integumentary System

Skin

The largest organ of the body.

Epidermis

Epithelial tissues, the outermost layer of the skin.

Dermis

Dense connective tissues, the layer of skin beneath the epidermis.

Subcutaneous Layer

Hypodermis, sits beneath the dermis.

Thick Skin

Hairless skin found on palms, soles, and flexor surfaces of digits.

Thin Skin

Hairy skin that covers large areas of the body.

Keratinization

Process where cells change shape and chemical composition, becoming filled with keratin.

Stratum Basale

Deepest layer of the epidermis, attached to the basement membrane, forms epidermal ridges.

Stratum Spinosum

Spiny layer of the epidermis, produced by division of the stratum basale.

Stratum Granulosum

Layer of the epidermis characterized by keratohyalin granules.

Stratum Lucidum

Clear layer of the epidermis, found only in thick skin.

Stratum Corneum

Most superficial layer of the epidermis, consists of dead squamous cells filled with keratin.

Dandruff

Excessive sloughing of stratum corneum cells from the scalp.

Callus

Hard skin; thickened area in skin subjected to friction due to increased layers in the stratum corneum.

Corn

Cone-shaped thickening of the stratum corneum over a bony prominence.

Dermal Papillae

Projections in the upper part of the dermis that extend toward the epidermis.

Cleavage Lines

Tension lines in the skin, also known as Langer lines.

Stretch Marks

Lines visible through the epidermis caused by damage to the dermis due to overstretching.

Hypodermis

Attaches the skin to underlying bone and muscle, contains adipose tissue for padding and insulation.

Hair Follicle

Invagination of the epidermis that extends deep into the dermis where hair arises from.

Hair Shaft

Part of the hair that protrudes above the surface of the skin.

Hair Root

Part of the hair below the surface of the skin.

Hair Bulb

Expanded, lowermost portion of the follicular epithelium that generates the hair.

Hair Papilla

Extension of the dermis that protrudes into the hair bulb.

Medulla

Core, innermost softer center of the hair, contains dead cells with soft keratin.

Cortex

Middle layer of the hair, contains dead cells with hard keratin for stiffness.

Cuticle (Hair)

Single outer layer of overlapping cells that holds the hair in the hair follicle.

Sebaceous Glands

Glands connected to hair follicles that produce sebum, an oily substance rich in lipids.

Eccrine Glands

Sweat glands located in almost every part of the skin, produce a secretion mostly water with a few salts.

Apocrine Glands

Sweat glands producing a thick secretion rich in organic substances, found in armpits and genitalia.

Nail Body

Visible part of the nail.

Nail Root

Part of the nail covered by skin, extends distally from the nail matrix.

Eponychium

Stratum corneum that extends onto the nail body, also known as the cuticle.

Nail Bed

Located distal to the nail matrix.

Nail Matrix

Area thicker than the nail bed, produces most of the nail.

Lunula

Whitish, crescent-shaped area at the base of the nail, a small part of the nail matrix.

Burn

Injury to tissue caused by heat, cold, friction, chemicals, electricity, or radiation.

First Degree Burns

Burns involving only the epidermis, red and painful, with slight edema.

Second Degree Burns

Burns that damage both the epidermis and dermis, may include redness, pain, edema, and blisters.

Third Degree Burns

Burns where the epidermis and dermis are completely destroyed, often painless due to destroyed sensory receptors.

Basal Cell Carcinoma

Most frequent type of skin cancer, begins in the stratum basale and extends into the dermis.

Squamous Cell Carcinoma

Develops from cells immediately superficial to the stratum basale, resulting in a keratinized tumor.

Malignant Melanoma

Rare form of skin cancer arising from melanocytes, usually in preexisting moles.