Integumentary System

Divisions of the integumentary system

skin and accessory organs

Skin

integument

• largest body organ

• two layers

  • epidermis: stratified epithelium tissue

  • dermis: connective tissue

    • hypodermis: below the dermis- not a part of the skin

Accessory organs

hair, nails, cutaneous glands

dermatology

treatment of the integumentary system

functions of the skin

• resistance to trauma and infection

• water retention- otherwise we would be drying up

• synthesis of vitamin D

• sensation: nerve endings- allow us to feel things that touch the skin

• thermoregulation

• nonverbal communication- facial expressions

epidermis

• outer layer of skin

• keratinized stratified squamous epithelium

• avascular

• nutrients received from the dermis

Cells of the epidermis

• stem cells

• keratinocytes

• melanocytes

• tactile (merkel) cells

• dendritic (langerhans) cells

stem cells

• divide and form mature cells

• only in deep layer of epidermis

• produce keratinocytes: keratin producing cells

keratinocytes

majority of visible epidermal cells

synthesize keratin

melanocytes

• in deep layer

• produce melanin pigment

• pigment picked up by melanocytes and incorporated into the nucleus to protect DNA from UV damage

tactile receptors

sense receptors; sense touch

dendritic cells

macrophage cells

layers of the epidermis

• stratum corneum

• stratum lucidum

• stratum granulosum

• stratum spinosum

• statum basale

five layers: superficial to deep

stratum corneum

up to 30 layers of dead cells mixed with keratin, lipids, and proteins

• forms layer resistant to abrasion, penetration, water loss

• the top layer- exfoliating

stratum lucidum

thin layer, only in thick skin of palms and soles

• only found here

stratum granulosum

3-5 layers of flat cells, dark staining granules that promote hydration, prevalent in thick skin

• thinner but not super thin

stratum spinosum

several layers of keratinocytes

• pretty big layer

stratum basale

basal layer of mainly cuboidal cells

How to memorize the layers

Can Lucy Give Some Blood

Dermis

• connective tissue

  • mainly collagen

• contains

  • blood vessels, neurons, cutaneous glands, hair follicles, piloerector muscles, and nail roots

• wavy boundary

• dermal and epidermal layers interdigitate

Hypodermis

• beneath areolar tissue of dermis, contains adipose tissue

  • below the dermis

• function-

  • support, bind to the dermis to deeper tissue and adipose storage

• also known as the subcutaneous layer

Skin color

melanin

melanin

produced by melanocytes located in stratum basale-found in the bottom layer, which is sb

• people of different ethnic groups have essentially the same number of melanocytes but express them differently

different expression of melanin, not number of cells

hemoglobin

red pigment of blood

-protein found in our blood

-greater hemoglobin production- pigment becomes red

carotene

yellow-orange pigment

concentrates in stratum corneum

it is found in carrots

why do we have different skin tones

melanin protects skin cells from UV

• clinical distribution - regions closer to the equator will be exposed to greater UV

cyanosis

blueness as a result of lack of oxygen

• better expressed in light colored peopl

erythema

redness as a result of increased blood flow

• maybe getting excited about something

pallor

pale or ashen as a result of reduced blood flow- anemia

albinism

genetic lack of melanin

jaundic

yellow skin

• indicates something is wrong in the liver (not breaking down a byproduct of metabolism)

bilirubin

hemoglobin waste excreted

hematoma

bruise

argyria

from colloidal silver

• whole body becomes blue

• people who work in an industry and are exposed to silver

pilus

filament or keratinized cells

grows from oblique tube called a hair follicle

grows almost everywhere, expect

• lips

• nipples

• palms and soles

torso and limb hair

sensory purpose

scalp hair

heat retention, protection from the sun

beard, pubic, and armpit hair

sexual maturity

dispersal of sexual scents

guard hairs

keep foreign objects out

eyebrows

enhance facial expression

reduce sun glare

help keep perspiration out of eyes

structure of hair and follicle

• bulb

• root

• shaft

hair bulb

swelling at base where hair originates in dermis

hair root

remainder of hair within follicle (dead cells)

hair shaft

portion above the skins surface (dead cells)

hair receptors

nerve fibers that sense movement of hair

pilorector muscle

they contact to give goosebumps

nails

derivatives of stratum corneum- most superficial layer

composed of very thin, dead, scaly cells with parallel rows of keratin

primates have nails rather than claws because it is easier to operate with nails

sweath glands (sudoriferous glands)

merocrine (eccrine) and apocrine

• apocrine- scent glands, groin, axilla

• merocrine- most abundant in palms, soles, forehead

  • cools the body

Sebaceous glands

secrete sebum, scalp, and face

• sebum is oily substance

ceruminous glands

only in the auditory canal (external ear)

• forms earwax or cerumen

mammary glands

milk producing glands; develop during pregnacy and lactation

Skin cancer

induced by UV rays (both natural and tanning beds)

common in elderly and fair-skinned

3 types

Basal cell carcinoma

arises in stratum basale

least dangerous

rarely metastasizes

squamous cell carcinoma

metastasizes

malignant melanoma

develops from damage to DNA of the cell from UV radiation

• most deadly

Burns

• causes of accidental death

• caused by hyperthermal damage to skin

  • UV radiation, spills, hot baths, electrical shock, strong chemicals

• death primarily from

  • fluid loss

  • infection

  • toxic effects of eschar-dead tissue