Anatomy & Physiology : The Intergumentary System

function of the dermis

basis of epidermis and makes up most of skin , flexibility

functions of the hypodermis

- loosely anchors skin to underying structures, mostly muscles
- shock absorption and insulation

the epidermis consists mostly of _____ _____ _____ _____

keratinized stratified squamous epithelium

the four ( 4 ) cell types of the epidermis :

- keratinocytes
- melanocytes
- dendritic cells
- tactile epithelial cells

four or five distinct layers of the epidermis :

deep to surface order :

- stratum basale
- stratum spinosum
|----------------------|
- stratum granulosum
- ( stratum lucidum )
- stratum corneum

thick skin is located where?

the palms, fingertips and soles (foot)

the thickest skin on the body is?

upper back skin

stratum basale

deepest layer of epidermis where new skin cells are produced
- active mitosis , attached to the dermis

stratum spinosum

prickly layer where cells start to produce keratin
- mutiple layers , attached to desmosomes
- resists tension and pulling
- keratinocytes in the layer appear spikey, so they're called prickle cells

stratum granulosum

a layer where cells further develop keratin and flatten.
- 4 to 6 cells thick but still thin layer
- where keratinization begins , helps form keratin fibers in upper layers
- cells above this layer die , cant survive

stratum lucidum ( only in thick skin )

a thin and clear layer present only in thick skin like the palms and feet
- 2 to 3 rows of clear, flat, dead keratinocytes
- superficial to the stratum granulosum

stratum corneum ( horny layer )

the outermost layer composed of dead, keratinized cells that are constantly shedding
- 20 to 30 rows of flat dead cells
- three-quarters of epidermal thickness

dead cells still function by

- protecting deeper cells from the environment
- prevent water loss
- protecting from abrasion and penetration
- acting as a barrier against biological, chemical and physical assaults

dermis

strong, flexible connective tissue
- fibroblasts, macrophages and occasionally mast cells and WBCs
- contains nerves, blood vessels, lymphatic vessels, epidermal hair follicles, oil glands and sweat glands

the two layers of the dermis

papillary dermis and reticular dermis

papillary dermis

the thin, superficial layer of areolar connective tissue ,
- contains loose, interlacing collagen and elastic fibers and blood vessels
- loose fibers allow phagocytes to patrol for microogranisms

The Integumentary system consists of :

- skin
- sweat glands
- oil glands
- hair
- nails
- subcataneous tissue

the skin consists of 2 layers ..

epidermis and dermis

epidermis

outermost protective shield of body
- epithelial tissue and avascular

dermis

underlies epidermis and makes up bulk of skin
- dense connective tissue and vascular

avascular

having a few or none blood cells

vascular

consisting of blood cells or blood vessels

hypodermis (subcataneous tissue )

not apart of the skin but shares some functions
- adipose tissue with some areolar connective tissue

function of the epidermis

protection

keratinocytes

produces fibrous keratin ( protective properties )

melanocytes

- spider-shaped cells in the deepest epidermis
- produces pigment melanin, which is then packaged into melanosomes

melanin protects keratinocyte nucleus from __ ______

UV damage

dendritic cells

- star-shaped macrophages ( WBCs ) that patrol the deep epidermis
- immune system

tactile epithelial cells

function in the sensation of touch at the epidermal-dermal junction

thick skin contains _ layers

5

thin skin contains _ layers

4

dermal papillae

superficial region of dermis that sends fingerlike projections up into epidermis
- contains capillary loops, free nerve endings
( pain and touch , tactile corpuscles )

friction ridges

the markings on the fingertips that leave oily fingerprints on surfaces we touch

dermal ridges

surface ridges of the epidermis of the palms and feet, where the sweat pores open

epidermal ridges

downward waves of epidermis

the functions of friction ridges

- enhances gripping ability
- contribute to sense of touch by enhancing vibrations detecting by receptors ( lamellar corpuscles )

friction ridges determined by :

genetics and womb environment

reticular dermis

80 - 85% of dermal thickness
- made up of coarse, dense irregular connective tissue
- tons of elastic fibers & collagen fibers help with stretching
- keeps skin hydrated by binding with water

dermal vascular plexus

network of blood vessels between reticular layer and hypodermis

what are cleavage ( tension ) lines ?

in reticular layer are caused by many collagen fibers running parallel to skin surface
- externally invisible
- important to surgeons because incisions parallel to cleavage - lines heal more readily

flexure lines

dermal folds at or near joints

flexure lines are visible on :

hands, wrists, fingers, soles ( feet ) and toes

striae

stretch marks

acute short-term traumas to the skin causes

blisters

three pigments contribute to skin color

melanin, carotene ( carrots ), hemoglobin

freckles and pigmented moles are local accumlations of what ?

melanin

excessive sun exposure damages skin and

causes alterations in DNA that may lead to skin cancer

UV light destroys

folic acid

blueness or cyanosis

low oxygen and hemoglobin , respiratory or cardiovascular issues

pallor or blanching

emotional stress, low blood pressure, anemia

redness or erythema

embarrassment, fever, inflammation or allergy

yellowness or jaundice

liver disorders

red/purple/green/yellow marks

blood leakage from damaged blood vessels under skin

brown or black patches

hyperpigmented, thickened skin in folds may be a sign of endocrine disorder

the more further away from the equator you are, the worse of a vitamin _ deficiency you'd get

D

repair can occur in two major ways:

regeneration: same kind of tissue replaces destroyed tissue, so original function is restored

fibrosis: connective tissue replaces destroyed tissue, and original function lost

tissue repair

repair starts very quickly, and inflammation is the function of repair

developmental aspects of tissues

- as the body ages, epithelia thin, so they are more easily breached
- tissue repair is less efficient
- bone, muscle tissues, and nervous tissues begin to atrophy
DNA mutations increase cancer risk

what does hair consist of?

dead keratinized cells

the functions of hair

- senses insects on skin before bite or stings
- hair on head guards against physical trauma
- protect from heat loss
- shield skin from sunlight
- eyelash shield eyes
- nose hairs filter particles from inhaled air

pili

hair

hair is produced by what

hair follicles

hair contains

hard keratin

root of the hair

the portion within the scalp, where keratinization is still going on

shaft

the portion that extends above scalp, where keratinization is complete

the three parts of the hair shaft include

- medulla : central core
- cortex : flattened cellls around the medulla
- cuticle : outer layer of single cells

red hair has an additional

pheomelanin pigment

how do gray hairs come about?

it happens when melanin production decreases and air bubbles replace melanin in the shaft

hair follicle

extends from epidermal surface to dermis

hair bulb

expanded area at deep end of follicle

hair is a sensory _____ receptor

touch

capillaries

smallest blood vessels that supply nutrients to growing hair

arrector pili

responsible for "goose bumps"

hair matrix

actively dividing area of the hair bulb that produces hair cells

vellus hair

pale, fine body hair of children and adult females

terminal hair

coarse, long hair

nutrition and hormones affect

hair growth

average _mm growth per week

2

terminal hair is replaced by vellus hair causing what?

wispy hair

testosterone

male sex hormone , helps body builders grow muscle and leads to hair loss

causes of thinning and texture change in hair :

- low thyroid hormone levels
- drugs
- severe dietary deficiencies of proteins or minerals

nails are

scale-like modifications of the epidermis with hard keratin

nails consist of

- root embedded in the skin
- nail plate or body visible attached portion
- free edge

nail bed

the epidermis underneath keratinized nail plate

nail matrix

thickened portion of bed responsible for nail growth

nail folds

skin folds that overlap border of nail

cuticle

nail fold that projects onto surface of the nail body

hyponychium

edge of nail that accumulates dirt

lunule

thickened nail matrix, appears white

sweat glands help control

body temperature

eccrine sweat glands

respond primarily to elevated body temperature

apocrine sweat glands

produce true sweat plus fatty substances and proteins; found in the axillary (armpit) and anogenital areas of the body

apocrine sweat glands begin to functioning at puberty ...

may act as a sexual gland

mammary glands

secrete milk

ceruminous glands

ear wax

oil glands secrete

sebum

acne

inflammation of the sebaceous glands, pimples, pustules, or cysts

the functions of skin

- protection
- body temp regulation
- cutaneous sensations
- metabolic functions
- blood
- excretion

skin has three barriers

- chemical
- physical
- biological

500 ml/day of unnoticeable sweat

insensible perspiration