Chapter 5: The Integumentary System

onset of puberty

onset of puberty

It is most common along with the ________ due to associated hormonal changes, but can also occur in infants and continue into adulthood.

excrete sebum

They generate and ________, a mixture of lipids, onto the skin surface, thereby naturally lubricating the dry and dead layer of keratinized cells of the stratum corneum, keeping it pliable.

skin cancers

It is the most fatal of all ________, as it is highly metastatic and can be difficult to detect before it has spread to other organs.

pale skin

Dark- skinned individuals produce more melanin than those with ________.

Skin

________ and its underlying tissue can be affected by excessive pressure.

Mutations

________ can lead to uncontrolled cell proliferation and malignancies.

fourth degree burn

A(n) ________ is even more severe, affecting the underlying muscle and bone.

second degree burn

A(n) ________ goes deeper and affects both the epidermis and a portion of the dermis.

keratinocyte

is a cell that manufactures and stores the protein keratin.

Keratin

is an intracellular fibrous protein that gives hair, nails, and skin their hardness and water-resistant properties.

absence of sun exposure

The ________ can lead to a lack of vitamin D in the body, leading to a condition called rickets, a painful condition in children where the bones are misshapen due to a lack of calcium, causing bowleggedness.

stratum basale

(also called the stratum germinativum) is the deepest epidermal layer and attaches the epidermis to the basal lamina, below which lie the layers of the dermis.

dermal papilla

(plural = dermal papillae) is found in the superficial portion of the dermis.

The skin is composed of two main layers

the epidermis, made of closely packed epithelial cells, and the dermis, made of dense, irregular connective tissue that houses blood vessels, hair follicles, sweat glands, and other structures

basal cell

is a cuboidal-shaped stem cell that is a precursor of the keratinocytes of the epidermis.

melanocyte

a cell that produces the pigment melanin.

Melanin

gives hair and skin its color, and also helps protect the living cells of the epidermis from ultraviolet (UV) radiation damage.

stratum spinosum

is spiny in appearance due to the protruding cell processes that join the cells via a structure called a desmosome.

Langerhans cell

Interspersed among the keratinocytes of this layer is a type of dendritic cell called the

stratum granulosum

has a grainy appearance due to further changes to the keratinocytes as they are pushed from the stratum spinosum.

keratohyalin

which accumulates as lamellar granules within the cells.

stratum lucidum

is a smooth, seemingly translucent layer of the epidermis located just above the stratum granulosum and below the stratum corneum.

eleiden

a clear protein rich in lipids, derived from keratohyalin, which gives these cells their transparent (i.e., lucid) appearance and provides a barrier to water.

stratum corneum

is the most superficial layer of the epidermis and is the layer exposed to the outside environment.

dermis

might be considered the “core” of the integumentary system (derma- = “skin”), as distinct from the epidermis (epi- = “upon” or “over”) and hypodermis (hypo- = “below”).

papillary layer

is made of loose, areolar connective tissue, which means the collagen and elastin fibers of this layer form a loose mesh.

Elastin fibers

provide some elasticity to the skin, enabling movement.

hypodermis

(also called the subcutaneous layer or superficial fascia) is a layer directly below the dermis and serves to connect the skin to the underlying fascia (fibrous tissue) of the bones and muscles.

melanosome

The melanin is transferred into the keratinocytes via a cellular vesicle called a

hair follicle

Strands of hair originate in an epidermal penetration of the dermis called the

hair shaft

is the part of the hair not anchored to the follicle, and much of this is exposed at the skin’s surface.

hair root

The rest of the hair, which is anchored in the follicle, lies below the surface of the skin and is referred to as the

hair matrix

The hair root ends deep in the dermis at the hair bulb, and includes a layer of mitotically active basal cells called the

hair papilla

which is made of connective tissue and contains blood capillaries and nerve endings from the dermis

internal root sheath

The cells of the ___ surround the root of the growing hair and extend just up to the hair shaft.

external root sheath

The ___, which is an extension of the epidermis, encloses the hair root.

glassy membrane

is a thick, clear connective tissue sheath covering the hair root, connecting it to the tissue of the dermis.

arrector pili

Each hair root is connected to a smooth muscle called the

anagen phase

, during which cells divide rapidly at the root of the hair, pushing the hair shaft up and out.

catagen phase

lasts only 2 to 3 weeks, and marks a transition from the hair follicle’s active growth.

telogen phase

, the hair follicle is at rest and no new growth occurs.

nail body

The is formed on the nail bed

eponychium

The nail fold that meets the proximal end of the nail body forms the nail cuticle, also called the

lunula

The nail bed is rich in blood vessels, making it appear pink, except at the base, where a thick layer of epithelium over the nail matrix forms a crescent-shaped region called the___(the “little moon”).

hyponychium

The area beneath the free edge of the nail, furthest from the cuticle, is called the

eccrine sweat gland

is a type of gland that produces a hypotonic sweat for thermoregulation.

apocrine sweat gland

is usually associated with hair follicles in densely hairy areas, such as armpits and genital regions.

sebaceous gland

is a type of oil gland that is found all over the body and helps to lubricate and waterproof the skin and hair.

cholecalciferol

In the presence of sunlight, a form of vitamin D3 called *__*is synthesized from a derivative of the steroid cholesterol in the skin.

rickets

a painful condition in children where the bones are misshapen due to a lack of calcium, causing bowleggedness.

Basal cell carcinoma

is a form of cancer that affects the mitotically active stem cells in the stratum basale of the epidermis.

melanoma

is a cancer characterized by the uncontrolled growth of melanocytes, the pigment-producing cells in the epidermis.

Eczema

is an allergic reaction that manifests as dry, itchy patches of skin that resemble rashes.

Acne

is a skin disturbance that typically occurs on areas of the skin that are rich in sebaceous glands (face and back).

first-degree

is a superficial burn that affects only the epidermis.

second-degree

burn goes deeper and affects both the epidermis and a portion of the dermis.

third-degree

burn fully extends into the epidermis and dermis, destroying the tissue and affecting the nerve endings and sensory function

fourth-degree

burn is even more severe, affecting the underlying muscle and bone.

scar

is collagen-rich skin formed after the process of wound healing that differs from normal skin.

stretch mark

results when the dermis is stretched beyond its limits of elasticity, as the skin stretches to accommodate the excess pressure.

corn

is a specialized form of callus.