Chapter 5

Thick Skin

Skin type found on palms of hands, soles of feet, and bottom of toes; hairless and has sweat glands only.

Thin Skin

Covers most of the body; contains hair, sebaceous oil glands, and sweat glands.

Functions of Skin

Includes resistance to trauma, water retention, vitamin D synthesis, sensation, thermoregulation, and nonverbal communication.

Epidermis

Outermost layer of skin, composed of multiple strata including stratum basale, spinosum, granulosum, lucidum, and corneum.

Stratum Basale

Deepest layer of the epidermis, one cell thick, responsible for new cell formation.

Stratum Spinosum

Thickest layer of the epidermis, where keratin synthesis begins.

Stratum Granulosum

Layer where cells begin to die as keratin replaces their nuclei and organelles.

Stratum Lucidum

Present only in thick skin, composed of dead, flattened keratinocytes.

Stratum Corneum

Outermost layer of dead cells that provides a water-repellent barrier.

Dermis

Layer beneath the epidermis, consisting of papillary and reticular layers, rich in blood vessels and connective tissue.

Papillary Layer

Superficial layer of the dermis made of areolar connective tissue.

Reticular Layer

Deep layer of the dermis made of dense irregular connective tissue.

Hypodermis

Not a skin layer, but contains adipose tissue and provides insulation and energy storage.

Melanin

Pigment produced by melanocytes, responsible for skin color variation.

Eumelanin

Type of melanin that is brownish-black.

Pheomelanin

Type of melanin that is reddish-yellow.

Cyanosis

Skin color indicating lack of oxygen, resulting in a bluish tint.

Erythema

Redness of the skin due to increased blood flow.

Pallor

Pale or ashen skin indicating reduced blood flow.

Albinism

Genetic condition resulting in no melanin production, leading to white skin.

Jaundice

Yellowing of the skin due to liver issues and bilirubin accumulation.

Friction Ridges

Patterns on fingertips that enhance grip and sensitivity.

Flexion Lines

Creases in the skin where it attaches to deeper tissues near joints.

Freckles

Flat, melanized patches of skin that vary with genetics and UV exposure.

Mole (Nevus)

Elevated patch of melanized skin, often referred to as a beauty mark.

Downy Hair (Lanugo)

Fine, unpigmented hair found on fetuses.

Vellus Hair

Fine, unpigmented hair covering most of the body, especially in women and children.

Terminal Hair

Coarse, pigmented hair found on the scalp, eyebrows, and after puberty.

Hair Bulb

Swelling at the base of the hair where it originates in the dermis.

Dermal Papilla

Structure providing nutrition to the hair.

Hair Matrix

Growth center of the hair where mitosis occurs.

Hair Follicle

Diagonal tube extending from the dermis to the hypodermis, housing the hair.

Eccrine Glands

Sweat glands that produce watery perspiration for cooling, found all over the body.

Apocrine Glands

Sweat glands located in specific areas that produce sweat with fat molecules, associated with odor.

Sebaceous Glands

Glands that produce sebum to keep skin and hair moisturized.

Ceruminous Glands

Glands in the auditory canal that secrete earwax to protect the ear.

Mammary Glands

Glands in females that produce milk during lactation.

Basal Cell Carcinoma

Most common and least dangerous skin cancer, arising from the stratum basale.

Squamous Cell Carcinoma

Skin cancer arising from keratinocytes, can metastasize to lymph nodes.

Malignant Melanoma

Most deadly skin cancer, arising from melanocytes, known for rapid metastasis.

First-Degree Burn

Affects only the epidermis, usually localized and mild.

Second-Degree Burn

Affects epidermis and part of the dermis, characterized by blisters and pain.

Third-Degree Burn

Destroys both epidermis and dermis, leading to severe damage and disfigurement.