Chapter 5 The Integumentary System

Epidermis

Superficial layer of the skin; composed of keratinized stratified squamous epithelium.

Dermis

Layer of skin deep to the epidermis; composed mostly of dense irregular connective tissue.

Hypodermis

Subcutaneous tissue just deep to the skin; consists of adipose plus some areolar connective tissue.

Keratin

Fibrous protein found in the epidermis, hair, and nails that makes those structures hard and water resistant.

Melanin

Dark pigment formed by cells called melanocytes; imparts color to skin and hair.

Dendritic cells

Protective cells that engulf antigens, migrate to lymph nodes, and present the antigen to T cells, causing them to activate and mount an immune response; those in the skin are sometimes called Langerhans cells.

Papilla

Small, nipple-like projection; e.g., dermal papillae are projections of dermal tissue into the epidermis.

Friction ridges

epidermal ridges atop deeper dermal ridges formed by dermal papillae, that enhance the gripping ability of the fingers and feet.

Cleavage (tension) lines

In reticular layer of dermis, are caused by many collagen fibers running parallel to skin surface.

Important to surgeons because incisions parallel to cleavage lines heal more readily.

Flexure lines

Dermal folds that occur at or near joints, where the dermis is tightly secured to deeper structures

Carotene

Yellow to orange pigment that accumulates in epidermis and in fatty tissue of the hypodermis.

Hemoglobin

Oxygen-transporting protein of erythrocytes that can give a pinkish hue to fair skin.

Cyanosis

Bluish discoloration of the skin generally due to low oxygenation of hemoglobin.

Jaundice

Yellowing of the skin and the whites of the eyes generally due to a liver disorder.

Bruise

An injury to a blood vessel causing the pooling and clotting of blood underneath the skin. As the clot is broken down by the body, the color of the bruise changes.

Insensible perspiration

Sweat that evaporates from the skin before it is perceived as moisture when the body is at rest.

Sensible perspiration

Water loss due to secretion by sweat glands that is designed to cool the body when the internal temperature is rising too high.

Sensory receptors

A cell or part of a cell (e.g. receptive endings of sensory neurons) specialized to respond to a specific stimulus.

Exteroceptors

Respond to stimuli arising outside the body; e.g.

receptors in the skin for touch, pressure, pain, and temperature, as well as most special sense organs

Basal cell carcinoma

Most common and least severe type of skin cancer; epidermal cells slowly invade dermis and hypodermis.

Squamous cell carcinoma

A type of skin cancer of the squamous epithelial cells in the epidermis

Melanoma

The most serious form of skin cancer that can easily spread to other parts of the body.