The Integumentary System: Anatomy, Layers, and Functions

Comprehensive vocabulary flashcards covering the anatomy, cellular composition, homeostasis mechanisms, and repair processes of the integumentary system.

Integumentary system

The organ system consisting of the skin, nails, and hair that provides a barrier between the environment, tissues, and organs within the body.

Skin

The largest organ in the body; absorbs nutrients, regulates internal body temperature, and eliminates waste.

Thermoreceptors

Sensory structures in the skin that detect changes in external temperature and send signals to the hypothalamus to maintain a stable internal temperature.

Vasodilation

The dilation of blood vessels in the dermis when the body overheats, increasing blood flow to the skin surface to release heat.

Vasoconstriction

The narrowing of blood vessels in cold conditions that reduces blood flow to the skin to conserve body heat.

Arrector pili muscles

Muscles that cause hairs to stand in cold conditions, trapping insulating air to conserve heat.

Epidermis

The outermost, superficial layer of skin composed of stratified squamous epithelial tissue that provides a barrier between the body and the surrounding environment.

Dermis

The middle, deeper layer of skin composed of connective tissue; contains sensory nerve receptors that respond to touch and pass signals to the peripheral nervous system.

Hypodermis

The deepest, fatty layer of skin tissue that is in contact with the muscles underneath it.

Keratinocytes

The predominant cells of the epidermis that produce keratin, a fibrous protein that protects the skin and tissue.

Stratum Basale

The deepest epidermal layer where keratinocytes are produced before pushing outwards toward the surface.

Stratum lucidum

An additional epidermal layer found only on the palms of the hands and soles of the feet, located between the stratum granulosum and stratum corneum.

Stratum corneum

The outermost epidermal layer consisting of $20\text{--}30$ layers of flat dead keratinocytes (corneocytes) filled with keratin and surrounded by glycolipid.

Corneocytes

Flat, dead keratinocytes filled with keratin and surrounded by glycolipid that form the protective barrier of the stratum corneum.

Papillary layer

The thin outer layer of the dermis composed of areolar tissue containing touch receptors called Meissner's.

Meissner's

Touch receptors located within the papillary region of the dermis.

Reticular region

The thick inner layer of the dermis composed of dense irregular connective tissue; contains nerves, sebaceous (oil) glands, sudoriferous (sweat) glands, and hair follicles.

Sudoriferous glands

Sweat glands that produce sweat, cooling the body as it evaporates to regulate body temperature.

Sebaceous glands

Glands that produce an oily substance to lubricate the skin and provide protection from bacteria.

Melanocytes

Epidermal cells that protect the pigment melanin, which absorbs ultraviolet rays.

Merkel cells

Epidermal cells that detect touch stimuli and transmit touch signals to sensory nerves.

Langerhans

Epidermal cells that assist in immune responses by identifying harmful microbes.

Fibroblast cells

Cells of the dermis that produce collagen and build new tissue during the proliferative phase of wound healing.

Mast cells

Cells involved in soft tissue repair that release histamine to dilate blood vessels.

Neutrophils and macrophages

White blood cells that consume bacteria and remove damaged tissue and debris during wound healing.

Proliferative phase

The phase of wound healing in which fibroblasts build new tissue by secreting collagen.

Vitamin D synthesis

The process triggered by sunlight ultraviolet radiation where skin cells produce vitamin D, which the liver and kidneys then modify to promote bone development.