Integumentary System (Chapter 6)

the skin

the skin and its accessory organs

the study of the integumentary system

• covers palms and soles
• epidermis is about 0.5mm thick
• sweat glands but no hair follicles or sebaceous glands

• epidermis is 0.1mm thick
• covers rest of the body
• has hair follicles, sweat glands and sebaceous glands

• resistant to trauma and infection
• barrier functions
• vitamin D production
• thermoregulation
• nonverbal communication

• keratinized stratified squamous epithelium
• above the dermis

• undifferentiated cells that divide and give rise to the keratinocytes
• only in the stratum basale

• majority of cells in epidermis
• synthesize keratin

• synthesize melanin
• only found in the stratum basale

• touch receptors
• few in number
• found in stratum basale
• associated with a dermal nerve fiber together making a tactile disc

• immune cells that originate from bone marrow
• found in the stratum spinosum and stratum granulosum

• 1. stratum basale
• 2. stratum spinosum
• 3. stratum granulosum
• 4. stratum lucidum
• 5. stratum corneum

• first layer of epidermis
• single layer of cuboidal to columnar cells and keratinocytes resting on the basement membrane
• contain stem cells

• second layer of epidermis (superficial to the stratum basale)
• several layers of keratinocytes
• thickest layer of thin skin
• deepest cells are capable of mitosis

• third layer of epidermis (superficial to the stratum spinosum)
• three to five layers of flat keratinocytes

• fourth layer of skin (superficial to the stratum granulosum)
• seen only in thick skin
• keratinocytes are densely packed
• pale, featureless with indistinct cell boundaries

• the fifth and most superficial layer of the epidermis
• up to 30 layers of dead, scaly, keratinized cells
• abrasion resistant
• water retention

connective tissue beneath the epidermis

• in the dermis
• upward waves
• fingerlike extensions into the epidermis
• tall papillae allow nerves close to skin surface

• in the dermis
• downward waves
• extension of epidermis into the dermis

thin zone of areolar connective tissue in and near dermal papillae

• deep to the papillary layer
• thick
• collagen forms thicker bundles with less room for ground substance

• also called subcutaneous layer
• below dermis
• boundary is indistinct
• pads the body and binds the skin to underlying tissue

• hypodermis composed of adipose tissue
• energy reservoir, thermal insulation
• absent in scalp
• abundant in breasts, hips, ect

• type of melanin
• brownish black pigment

• type of melanin
• reddish yellow pigment
• contains sulfer

• red pigment in blood
• imparts red/pink color to the skin when blood vessels are close to surface

• yellow pigment
• can become condensed in corneum layer and subcutaneous fat

turning blue

pale skin due to little blood flow through skin.

red or flushed look to the skin

lack of melanin

yellowing of the skin and sclera from high levels of bilirubin

bruise

finger prints

lines formed where skin folds during flexion of joints

flat melanized patches that very with heredity and exposure to sun

elevated patch of melanized skin

patched of skin discolored by benign tumors of capilaries

• plural pili
• hair

oblique tube in the skin where hair grows from

fine, downy, unpigmented hair that appears on the fetus in the last three months of development

• fine, pale hair
• two-thirds of hair on women
• one-tenth of hair on men
• all hair on children except eyelashes, eyebrows, and scalp hair

• long, coarse, more heavily pigmented hair than lanugo and vellus
• eyebrows, scalp hair, eyelashes
• after puberty pubic hair, axillary hair, facial hair, and some hair on trunk and limbs

a swelling at the base of that hair where it originated from the dermis

the hair within the follicle excluding the bulb

the portion of hair above the skin

• bulb of vascular connective tissue
• provide hair with nutrients

• mitotically active cells
• center of hair growth
• all cells above are dead

core of loosely arranged cells and air space found in a cross section of hair

• constitutes most of the bulk of hair
• several layers of elongated keratinized cells that appear cuboidal to flattened

composed of multiple layers of very thin, scaly cells overlapping each other like roof shigles

• an extension of the epidermis
• composed of stratified squamous epithelium
• lied immediately adjacent to the hair root

derived from the dermis and is somewhat denser than adjacent dermal tissue

• where the follicle widens
• source of stem cells and follicle growth

nerve fibers that entwine each follicle and respond to hair movement

• a bundle of smooth muscle cells extending from the dermal collagen fibers to the connective tissue root sheath of the follicle
• raises hair and create "goose bumps"

• consisting of three developmental stages
• anagen
• catagen
• telogen

• 90% of hair growth
• stem cells from the bulge multiply and travel downward, pushing dermal papilla deeper into the skin, forming the dermal epithelial root sheath

• mitosis in the hair matrix ceases
• sheath cells die

• hair with the base keratinized into a hard club
• can easily fall out or be pulled out

resting period

hair loss

excessive or undesirable hair growth

• guard hairs
• guard nostrils and inner ear canals
• eyelashes
• eyebrows

hard part of the nail

visible attached part of the nail

unattached overhanding portion of the nail

extends proximally under the overlying skin

surrounding skin raised above the nail

the margin of the nail

skin underlying the nail plate

epidermis of the nail bed

growth zone of the nail

white half moon at the proximal and of the nail

cuticle

swear glands

• occur in the groin, anal region, axilla, and areola
• use exocytosis
• respond to stress

• widely distributed over the body
• abundant in palms, sloes, and forehead

• found amid secretory cells at the deep end of merocrine and apocrine glands
• have properties similar to smooth muscle

perspiration that evaporates as it is excreted

• heavy sweating
• can loose up to on liter of water an hour

secret sebum

secrete cerumen or ear wax

• milk producing glands
• only active during pregnancy and lactation

• most common type of skin cancer
• seldom metastasized
• starts in the stratum basale and eventually invades the dermis
• lesions appear as a small shiny bump

• arises from keratinocytes in the stratum spinosum
• lesions usually appear on the scalp, a concaved ulcer with raised edges

• arises from melanocytes
• accounts for 5% of skin cancer
• extremely aggressive and drug resistant
• if metastasized is unresponsive to chemo

burned, dead tissue

• a burn only affecting the epidermis
• also called partial thickness burn
• edema and pain
• seldom leave scars

• affects the epidermis and part of the dermis
• also called partial thickness burns
• forms blisters

• also full thickness burns
• epidermis and all of the dermis is damaged
• takes a long time to heal and often requires skin grafts

removing dead skin and debris from burns

skin graft from the patient

skin graft taken from the patients identical twin

skin graft from another person

skin graft from a pig or other animal