The Integumentary System

A comprehensive set of practice flashcards covering the anatomy, physiological functions, layering, pigmentation, and repair processes of the human integumentary system based on lecture slides.

What percentage of total body weight does the integumentary system represent?

$$16\%$$

What is the estimated surface area of the integumentary system?

$$1.5\text{ to }2\,m^2$$

What are the two main parts that make up the integument?

Cutaneous membrane (skin) and accessory structures.

Which two components form the cutaneous membrane?

The outer epidermis (superficial epithelium) and the inner dermis (connective tissues).

Where do accessory structures, such as hair, nails, and multicellular exocrine glands, originate?

In the dermis.

What is the hypodermis and where is it located?

Also known as the superficial fascia or subcutaneous layer, it is loose connective tissue located below the dermis.

List the primary functions of the skin.

Protection of underlying tissues, excretion of salts/wastes, maintenance of body temperature, production of melanin and keratin, synthesis of vitamin $D_3$, storage of lipids, detection of touch/pressure/pain, and coordination of immune response.

What type of epithelium makes up the epidermis?

Avascular stratified squamous epithelium.

Which epidermal cells are the most abundant and contain large amounts of keratin?

Keratinocytes.

Compare the number of keratinocyte layers in thin skin versus thick skin.

Thin skin covers most of the body and has four layers; thick skin covers the palms and soles and has five layers.

What are the five strata of the epidermis in thick skin, ordered from the basement membrane to the surface?

Stratum basale, Stratum spinosum, Stratum granulosum, Stratum lucidum, and Stratum corneum.

How is the stratum basale attached to the basement membrane?

By hemidesmosomes.

What structures are responsible for fingerprints?

Epidermal ridges.

What is the function of Merkel cells (tactile cells)?

Found in hairless skin, they respond to touch and release chemicals that trigger the nervous system.

What are the characteristic cells of the stratum spinosum that are active in the immune response?

Dendritic (Langerhans) cells.

Which layer of the epidermis is known as the "grainy layer" where cells stop dividing and start producing keratin?

Stratum granulosum.

Which layer of the epidermis is found only in thick skin?

Stratum lucidum (the "clear layer").

How many layers of keratinized cells are typically found in the stratum corneum?

$15\text{ to }30$ layers.

How long does it take for a cell to move from the stratum basale to the stratum corneum?

$7-10$ days.

Define insensible perspiration versus sensible perspiration.

Insensible perspiration is interstitial fluid lost by evaporation through the stratum corneum; sensible perspiration is water excreted by sweat glands.

What causes the skin on fingertips to wrinkle after a long soak in water?

The constriction of underlying blood vessels caused by the autonomic nervous system.

What are the two layers of the dermis?

The outer papillary layer and the deep reticular layer.

Which dermal layer consists of dense irregular connective tissue and contains collagen and elastic fibers?

Reticular layer.

What is dermatitis?

An inflammation of the papillary layer caused by infection, radiation, mechanical irritation, or chemicals.

Compare the properties of collagen fibers and elastic fibers in the dermis.

Collagen fibers are very strong and resist stretching but bend easily; elastic fibers permit stretching and recoil to their original length.

What are cleavage (tension) lines?

Parallel bundles of collagen and elastic fibers in the dermis that resist force in a specific direction.

Distinguish between tactile corpuscles and lamellated corpuscles.

Tactile corpuscles (in dermal papillae) detect light touch; lamellated corpuscles (in the reticular layer) detect deep pressure and vibration.

What are the two primary pigments influencing skin color?

Carotene (orange-yellow) and melanin (red-yellow or brown-black).

What is cyanosis?

A bluish skin tint caused by a severe reduction in blood flow or oxygenation.

Which condition results from the liver's inability to excrete bile, leading to a yellow skin tint?

Jaundice.

How is vitamin $D_3$ (cholecalciferol) processed by the body?

Epidermal cells produce it in the presence of UV radiation; the liver and kidneys then convert it into calcitriol to aid calcium and phosphorus absorption.

What clinical condition can result from insufficient vitamin $D_3$?

Rickets.

What is the function of the arrector pili muscle?

It is the muscle associated with hair follicles that causes hair to stand up (goosebumps).

Identify the two types of sweat glands in the skin.

Apocrine glands (odorous secretions in armpits/groin) and merocrine or eccrine glands (watery secretions for cooling).

What is sebum and which gland secretes it?

Sebum is a lipid-based secretion that lubricates the skin and inhibits bacteria; it is secreted by sebaceous glands.

Describe the four phases of integument repair following an injury.

1. Inflammatory phase (bleeding/mast cells); 2. Migratory phase (scab/stratum basale migration); 3. Proliferation phase (fibroblast activity); 4. Scarring phase (scar tissue/keloid formation).

What is the Rule of Nines for an adult?

A method to estimate burn area: Head $9\%$, each upper limb $9\%$, trunk $36\%$, genitalia $1\%$, and each lower limb $18\%$.

List common effects of aging on the integumentary system.

Epidermal thinning, decreased dendritic cells, reduced vitamin $D_3$ production, decreased melanocyte and glandular activity, reduced blood supply, and slower repair rate.