CH 5: INTEGUMENTARY SYSTEM

consists of the skin and accessory structures, such as hair, glands, and nails

integumentary system

general functions of the integumentary system (5)

protection
sensation
temperature regulation
vitamin D production
excretion

an important regulator of calcium homeostasis

vitamin D

the skin's two major tissue layers

epidermis
dermis

is the superficial layer of the skin, consisting of stratified squamous epithelial tissue

epidermis

type of tissue found in the epidermis

stratified squamous epithelial tissue

the epidermis rests on a layer of this connective tissue

dermis

a layer of loose connective tissue that connects the skin to underlying muscle or bone

subcutaneous tissue or hypodermis

cells of the epidermis that produce keratin

keratinocytes

produce the pigment melanin, which contributes to skin color

melanocytes

are part of the immune system of the epidermis

Langerhans cells

are specialized epidermal cells associated with the nerve endings responsible for detecting light touch and superficial pressure

Merkel cells

a process where the cells accumulate keratin

keratinization

the many layers of cells in the epidermis are divided into regions

strata

5 strata of the epidermis (deepest to most superficial)

stratum basale
stratum spinosum
stratum granulosum
stratum lucidum
stratum corneum

is the deepest portion of the epidermis

stratum basale or stratum germinativum

Superficial to the stratum basale

stratum spinosum

keratin fibers and lipid-filled, membrane-bound organelles

lamellar bodies

consists of two to five layers of somewhat flattened, diamond-shaped cells

stratum granulosum

protein found in the stratum granulosum

keratohyalin

Three to five layers of dead cells; appears transparent;
present in thick skin, absent in most thin skin

stratum lucidum

Deepest stratum of the epidermis; single layer of
cuboidal or columnar cells

stratum basale

2 layers of the dermis

papillary layer
reticular layer

Not part of the skin; loose connective tissue with
abundant deposits of adipose tissue

subcutaneous tissue

how many layers of skin are the stratum corneum

25 or more layers

Prevents water loss and the entry of chemicals and microorganisms

epidermis

Provides structural strength due to keratin within cells; prevents water loss due to lipids surrounding cells; sloughing off of most superficial cells resists abrasion

stratum corneum

Disperses keratohyalin around keratin fibers

stratum lucidum

cells found in stratum lucidum

keratohyalin

thin, clear zone above the granulosum

stratum lucidum

are dead keratinocytes, with a hard protein envelope, filled with the protein keratin

cornified cells

Keratin is a mixture of

keratin fibers and keratohyalin

has all five epithelial strata

thick skin

when the stratum corneum of the epidermis increases in thickness

callus

factors that determine skin color [3]

pigments in the skin
blood circulating through the skin
thickness of stratum corneum

is the group of pigments primarily responsible for skin, hair, and eye color

melanin

melanin is produced by ____

melanocytes

Melanocytes produce and package melanin into vesicles called

melanosomes

an enzyme that converts the amino acid tyrosine to dopaquinone

tyrosinase

factors that determine melanin production [3]

genetic factors, exposure to light, and hormones

a recessive genetic trait that results from an inability to produce tyrosinase

albinism

a condition in which the skin turns a reddish hue when
the amount of blood flowing through the skin increases

erythema

a bluish skin color cause by decrease in blood flow and oxygen content

cyanosis

is a yellow pigment found in plants, such as carrots and corn

carotene

cells of the dermis [3]

fibroblasts
adipocytes
macrophages

nerve endings found in the dermis [5]

free nerve endings for pain, itch, tickle, temperature
hair follicle receptors
Pacinian corpuscles for deep pressure
Meissner corpuscles for simultaneous stimulation 
Ruffini end organs for continuous touch or pressure

loose connective tissue with thin fibers that are somewhat loosely arranged, contains blood vessels that supply the epidermis

papillary layer

improve the grip of the hands and feet

friction ridges

The orientation of collagen fibers

cleavage lines or tension lines

lines of scar tissue that can develop in the skin of individuals who have experienced rapid growth

stretch marks

other name for subscutaneous tissue

hypodermis

functions of the subcutaneous tissue [3]

insulation
padding
source of energy

type of tissue found in the subcutaneous layer

adipose tissue

3 types of injections

intradermal injection
subcutaneous injection
intramuscular injection

type of injection that goes into the dermis

intradermal injection

type of injection that extends into the subcutaneous tissue

subcutaneous injection

type of inejction that reaches a muscle deep to the subcutaneous tissue

intramuscular injection

types of structures that are embedded in or otherwise associated with the epidermis and dermis

accessory structures

delicate, unpigmented hair in fetuses

lanugo

long, coarse, and pigmented hairs near the time of birth

terminal hairs

are short, fine, and usually unpigmented, replace the lanugo on the rest of the body

vellus hairs

the hair is divided into (3) parts

shaft
hair root
hair bulb

hair part that protrudes above the surface of the skin

shaft

hair part that is located below the surface

hair root

The base of the root is expanded to form this

hair bulb

3 layers of the hair

medulla
cortex
cuticle

is the central axis of the hair, and it consists of two or three layers of cells containing soft keratin

medulla

surrounds the medulla and forms the bulk of the hair

cortex

the cortex is covered by a single layer of cells also containing hard keratin

cuticle

is a tubelike invagination of the epidermis that extends into the dermis

hair follicle

is the portion of the dermis that surrounds the epithelial root sheath

The dermal root sheath

a yellowish skin color, occurs when excess bile pigments accumulate in the blood

jaundice

where a mass of undifferentiated epithelial cells inside the hair bulb

hair matrix

where blood vessels are located that provide nourishment to the cells of the hair matrix

hair papilla

hair cycle [2]

growth stage and resting stage

at this stage, hair increases in length as new matrix cells are produced, differentiate, become keratinized, and die

growth stage

the stage where hair growth stops; the hair follicle shortens and holds the hair in place

resting stage

smooth muscle cells associated with each hair follicle

arrector pili

major glands of the skin [2]

sebaceous glands
sweat glands

shape of sebaceous glands

simple or compound alveolar glands

an oily, white substance rich in lipids

sebum

what type of secretion glands are sebaceous glands

holocrine glands

2 types of of sweat or sudoriferous glands

eccrine glands and apocrine glands

are the most common type of sweat gland; simple, coiled, tubular glands that open directly onto the surface of the skin through sweat pores

eccrine sweat glands

subdivisions of eccrine sweat glands

(1) the deep, coiled portion, which is located mostly in the dermis
(2) the duct, which passes to the skin surface

eccrine sweat glands are also called _____

merocrine sweat glands

what type of fluid is sweat

hyposmotic fluid

are simple, coiled, tubular glands that usually open into hair follicles superficial to the opening of the sebaceous glands

apocrine sweat glands

are modified eccrine sweat glands located in the ear canal

ceruminous glands

is composed of the combined secretions of ceruminous glands and sebaceous glands

cerumen or earwax

are modified apocrine sweat glands located in the breasts

mammary glands

is a thin plate consisting of layers of dead stratum corneum cells that contain a very hard type of keratin

nail

the skin covering the nail edges

nail fold

edges of the nail that are held in place

nail groove

another word for cuticle

eponychium

thickened region of stratum corneum beneath the free edge of the nail body

hyponychium

a whitish, crescent-shaped area at the base of the nail

lanula

what type of connective tissue is the reticular layer of the dermis made of

irregular dense connective tissue

the process in which blood vessels (1) dilate (2) constrict

vasodilation
vasoconstriction

why is vitamin d important

for calcium and phosphate homeostasis