ex 2

16 percent body weight and covers an area of 1.5 to 2msquared

How much does the skin make up in the adult human body?

True

The skin and accessory structures are the largest organ system in the human body

T or F

Integumentary system

-the skin and its accessory structures

-provides the body with overall protection

multiple layers of cells and tissues

What is the skin made of?

connective tissue

The skin's layers of cells and tissues are held to underlying structures by?

False, it is well vascularized (has numerous blood vessels)

The deepest layer of the skin is not vascularized

T or F

sensory, autonomic, and sympathetic fibers

What does the integumentary system have that ensures communication to and from the brain?

Epidermis

composed of keratinized, stratified squamous epithelium

True

The epidermis is avascular

T or F

thin skin

Skin that

has four layers of cells is referred to as:

-stratum corneum

-stratum lucidum

-stratum granulosum

-stratum spinosum

-stratum basale

what are the layers of the epidermis?

True

Most of the body is classified as thin skin

T or F

Thick Skin

is found

only on the palms of the hands and the soles of the feet

Keratinocyte

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

Stratum Basale

is the deepest epidermal layer and attaches the epidermis to the

basal lamina, below which lie the layers of the dermis

basement membrane

what do the cells in the stratum basale bond to?

Dermal Papilla

-is found in the superficial portion of the dermis

-increase the strength of the

connection between the epidermis and dermis; the greater the folding, the stronger the connections made

basal cell

a cuboidal-shaped stem cell that

is a precursor of the keratinocytes of the epidermis

Merkel Cell

functions as a receptor and is responsible for stimulating sensory nerves that

the brain perceives as touch

surfaces of the hands and feet

where is the merkel cell abundant?

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

In a growing fetus, fingerprints form where the cells of the stratum basale meet the papillae of the underlying dermal layer

(papillary layer), resulting in the formation of the ridges on your fingers

How do fingerprints form?

False, they do not change

patterns change with the growth and aging process

T or F

stratum spinosum

-spiny in appearance because of desmosome

-composed of eight to 10 layers of keratinocytes,

formed as a result of cell division in the stratum basale

desmosome

the protruding cell processes that join the cells

via a structure

the staining process

The spiny structure of the stratum spinosum is due to:

True

Unstained epidermis samples do not exhibit the spiny nature

T or F

Langerhans cell

-interspersed among the keratinocytes

-functions as a macrophage by engulfing bacteria, foreign particles,

and damaged cells that occur in this layer

-begin w/ synthesis of keratin

-release glycolipid that helps prevent water loss from the body (waterproof)

-as new keratinocytes are produced atop the stratum basale, the keratinocytes of the stratum spinosum are pushed into the stratum granulosum

How does the keratinocytes in the stratum spinosum begin?

Stratum Granulosum

-has a grainy appearance due to further changes to the keratinocytes as they are pushed from the

stratum spinosum

keratohyalin

accumulates as lamellar granules within the

cells

proteins keratin and keratohyalin

2 proteins that make up the bulk of the keratinocyte mass in the stratum granulosum and give

the layer its grainy appearance

keratin and keratohyalin

2 proteins that make up the bulk of the keratinocyte mass in the stratum granulosum and give

the layer its grainy appearance

stratum lucidum

smooth, seemingly translucent layer of the epidermis located just above the stratum granulosum

and below the stratum corneum

only in the thick skin of the palms, soles, and digits

where is the stratum lucidum found?

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

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

increased keratinization

what gives the stratum corneum its name?

15 to 30 layers

How many layers of cells are in the stratum corneum?

-helps prevent the penetration of microbes and the

dehydration of underlying tissues,

-provides a mechanical protection against abrasion for the more delicate, underlying

layers

What is the function of the stratum corneum?

Microdermabrasion

helps remove some of the dry, upper layer and aim to keep skin looking "fresh" and healthy

True

cells in the stratum corneum layer are shed periodically and are replaced by cells pushed up from the stratum granulosum

T or F

4 weeks

How long until the stratum corneum is replaced?

dermis

considered the "core" of the integumentary system (derma- = "skin"), as distinct from the epidermis

(epi- = "upon" or "over") and hypodermis (hypo- = "below").

blood and lymph vessels, nerves, and other

structures, such as hair follicles and sweat glands

What does the dermis contain

two layers of connective tissue that compose an

interconnected mesh of elastin and collagenous fibers, produced by fibroblasts

What is the dermis made of

Papillary Layer

made of loose, areolar connective tissue, which means the collagen and elastin fibers of this layer

form a loose mesh

fibroblasts, adipocytes, and an abundance of small blood vessels

What is within the papillary layer?

-phagocytes to help fight bacteria/infections

-lymphatic capillaries

-nerve fibers

-Meissner corpuscles

In addition, what does the papillary contain?

Meissner corpuscles

touch receptors found in the papillary layer

reticular layer

-underlies the papillary layer

-composed of dense irregular connective tissue

True

The reticular layer is vascularized and has a rich sensory and sympathetic nerve supply

T or F

Elastin fibers

provide some elasticity to the skin, enabling movement

Collagen fibers

-provide structure and tensile strength, with strands of collagen extending into both the papillary layer and the

hypodermis

-binds water to keep the skin hydrated

Collagen injections and Retin-A creams

help

restore skin turgor by either introducing collagen externally or stimulating blood flow and repair of the dermis, respectively

Hypodermis

-layer directly below the dermis and serves

to connect the skin to the underlying fascia of the bones and muscles

False, it is NOT strictly a part of then skin

The hypodermis is strictly a part of the skin

T or F

well-vascularized,

loose, areolar connective tissue and adipose tissue

What does the hypodermis consist of?

well vascularized,

loose, areolar connective tissue and adipose tissue

functions as a mode of fat storage and provides

insulation and cushioning for the integument

The nuclei and other cell organelles disintegrate as the cells die, leaving behind the keratin,

keratohyalin, and cell membranes

how does the stratum lucidum, stratum corneum, and the accessory structures of hair and nails form?

True

Most of the skin is classified as thin skin

T or F

4 or 5 epithelial cells depending on the location

how many layers of epithelial cells does the epidermis have?

melanosome

keratinocytes via a cellular vesicle

Eumelanin

exists as black and brown

pheomelanin

provides a red color

moles

larger masses of melanocytes

freckles

irregular accumulation of melanocytes in the skin

hair

a keratinous filament growing out of the epidermis

hair follicle

epidermal penetration of the dermis

hair shaft

the part of the hair not anchored

to the follicle, and much of this is exposed at the skin's surface

hair bulb

deep in the dermis where the hair root ends

hair matrix

a layer of mitotically active basal cells

hair papilla

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

medulla

forms the central core of the hair

cortex

a layer of compressed, keratinized cells

cuticle

very hard, keratinized cells

internal root sheath

surround the

root of the growing hair and extend just up to the hair shaft

external root sheath

an extension of the epidermis, encloses the hair root

glassy membrane

a thick, clear connective tissue

sheath covering the hair root, connecting it to the tissue of the dermis

arrector pili muscle

smooth muscle that contracts in response to nerve signals from the sympathetic nervous system, making

the external hair shaft "stand up."

anagen phase

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 bed

specialized structure of the epidermis that is found at the tips of our fingers and toes

nail body

protects the tips of our fingers and toes as they are the farthest extremities and the parts of

the body that experience the maximum mechanical stress

nail root

has a matrix of proliferating cells from the stratum basale that enables the nail to grow continuously

nail fold

overlaps the nail on the sides, helping to anchor the nail body

eponychium

The nail fold that meets the proximal end of the nail body forms the:

lunula

a thick layer of epithelium over the nail matrix forms a crescent-shaped region

hyponychium

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

sudoriferous glands

produce sweat to cool the body

eccrine sweat gland

type of gland that produces a hypotonic sweat for thermoregulation

apocrine sweat gland

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

sebaceous glands

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

sebum

a mixture of lipids

meissner corpuscle (tactile corpuscle)

responds to

light touch

pacinian corpuscle (lamellated corpuscle)

responds to vibration

vitamin D

what does the epidermal layer of the skin synthesize wen exposed to UV radiation?