Chapter 5: The Integumentary System

Epidermis

The superficial layer of the skin made of keratinized stratified squamous epithelium.

Dermis

The deep layer of the skin that contains blood vessels, nerves, and glands.

Hypodermis

Also known as subcutaneous tissue, it is not part of the skin and consists of adipose tissue for insulation and shock absorption.

Stratum Basale

The deepest layer of the epidermis where mitotic cells are actively dividing; contains melanocytes and Merkel cells.

Stratum Spinosum

Layer of the epidermis with several layers of keratinocytes connected by desmosomes for strength.

Stratum Granulosum

Layer of the epidermis where cells begin to die and produce keratohyalin granules for waterproofing.

Stratum Lucidum

A transparent layer of the epidermis found only in thick skin, such as the palms and soles.

Stratum Corneum

The outermost layer of the epidermis made of dead keratinized cells that provide protection.

Functions of the Skin

Includes protection, temperature regulation, cutaneous sensation, metabolic functions, blood reservoir, and excretion.

Basal Cell Carcinoma

The most common and least dangerous type of skin cancer that originates in the stratum basale.

Squamous Cell Carcinoma

A type of skin cancer that can spread, originating in the stratum spinosum.

Melanoma

The most dangerous type of skin cancer that arises from melanocytes.

ABCD Rule

A guideline for identifying melanoma by assessing Asymmetry, Border irregularity, Color variation, and Diameter greater than 6mm.

Protection

The skin acts as a barrier against mechanical injury, pathogens, and harmful substances.

Temperature Regulation

The skin helps regulate body temperature through sweat production and blood vessel dilation or constriction.

Cutaneous Sensation

The skin contains sensory receptors that detect touch, pain, temperature, and pressure.

Metabolic Functions

The skin synthesizes vitamin D when exposed to sunlight, which is important for calcium absorption.

Blood Reservoir

The skin can hold a large volume of blood, which can be redirected to other parts of the body when needed.

Excretion

The skin helps remove waste products and toxins through sweat.