A&P 201 unit 2 skin

• skin
• hair
• nails
• glands

found in the dermis of the skin which is composed of connective tissue

• dermis
• epidermis

• glands
• arrector pili muscles
• and hairs

• Meissner's corpuscles
• pacinian corpuscles
• and free nerve endings

kerartinazed stratified squamous epithelium

• 1. found in the deepest layers of the epidermis
• 2. keratin

• 1. found in the stratum basale (basal layer) of the epidermis
• 2. produce melanin,a dark skin pigment, it helps protect skin cells from cancerous uv rays

• found in the stratum basale
• come in contact with sensory neurons
• involved in touch sensation

• they are macrophage like cells that provide a immune response against foreign cells that invade the body surface
• they migrate from the red bone marrow to the stratum spinosum

• outter most layer of the epidermis
• composed of a tightly packed layer of dead cells heavily kertanized
• layer is very thick in thick skin(palms,or soles of feet)

• layer of epidermis appears somwhat clear
• most cells are dead
• its greatly reduced in thin skin
• easily seen in thick skin

• layer of epidermis
• appears granular
• composed of living cells

• layer of epidermis
• composed of spiny shaped cells
• contains Langerhans's cells
• composed of living cells

• innermost layer of the epidermis
• a single cell thick
• the most active cell division occurs here
• contains melanocytes and Merkel cells
• composed of living cells

from the bottom up (like all epithelial tissue)

• mitosis occurs in the stratum basale
• living cells pushed towards the surface
• living cells kertanized flatten and die as they get closer to the surface
• dead cells are sloughed off at the surface

dense irregular connective tissue richly supplied with blood vessels and nerves

• layer of the dermis
• contains the dermal papillae

• helps hold the epidermis to the dermis
• increases surface area for exchange of nutrients with the epidermis
• contributes to fingerprints

• 80% of the thickness of the dermis
• found below the papillary layer
• contains most of the structure of the dermis

• 1. found in the dermal papillae involved in light touch sensation
• 2. deep in the dermis sensative to deep pressure
• 3. involved in the sensation of the warmth, coolness, pain, tickling and itching

• "below the skin" also called the superfical fascia
• 1. site for storage of fat
• 2. helps to loosely anchor the skin to mostly muscles
• 3. helps to insulate the body to prevent heat loss

• melanin
• carotene
• hemoglobin

they are all eithelial in orgin but are found in the underlying connective tissue

• have a duct
• make an external secretion
• examples are oil and sweat glands of the skin

• do not have a duct
• make an internal secretion
• secrete hormones into the blood to be carries elsewhere in the body
• collectively form the endocrine system

distrubuted over almost the entire body surface

• most numerous type of sweat gland
• produce true sweat in response to:
• elevated temp. nervousness spicy foods,
• composed of simple cubodial epithelium

• found in the axillary anal and genital areas
• produce a milky or yellowish colored sweat

• found in the ears
• produce ear wax

• found in all skin except palms and soles of feet.
• produce an oily substance called seabumwhich collects dirt softens and lubricates hair keeps epidermis from crcking kills bacteria and slows water loss

• dead kertanized epithelial cells
• sense things that lightly touch the head
• protects the head from direct sunlightin the summer and heatloss in the cold
• eyelashes shield the eyes
• nse hairs filter particles from incoming hair

• shaft is the part coming out of the skins surface
• the root is below

hair is enclosed in a hair follicle

• central core of hair
• surrounds the medulla of the hair
• outtermost layer of the hair
• surrounds the hair

• region of high cell divison growing region of hair
• produce pigment of hair
• stimulates hair growth and supplies nutrients to growing hair
• surrounds hair
• expanded end of the hair follicle

• attaches to the hair follicle
• contraction of muscle in response to cold or fear causes the hair to stand erect (goose bumps)
• useful in animals to provide warmth and look dangerous to ememies

• like the hair is composed of dead keratinized epithelial cells
• and hard keratin

the most distal part of the nail

the area below the free edge of the nail

the visable attached part

the proximal part (embedd in the skin)

the cuticle

• the actively growing part of thr nail
• also where the highest mitosis occurs

the white cresent area

• cushions and insulates deeper organs
• protects body from bumps scrapes and cuts
• protects body from chemicals and changes in temp.
• retards water loss
• acts as a mini excretory system
• screens out uv rays from the sun
• contains sensory receptors associated with nerve endings
• makes vitamin D in the presence of sunlight

• blood is shunted to the bodies surface in order to cool the body
• blood is shunted away from the skin therefore maintaining a warmer temp.

by sweating also called evaporative cooling

in both epithelial and connective tissue of the skin

• bleeding occurs at the injury site there is an inflammatory response
• blood clot formedand scab produce macrophages remove debri in the scab fibroblasts invade deeper areas of the injury
• the injury is surrounded by epithelial cells by a week, phagocytes disenagrate the scab
• scab is shed epidermis is complete, fibroblasts continue to create scar tissue

caused byshort term but acute trauma resukts in the seperation of teh epidermal and dermal layers by a fluid filled pocket

local accumulations of melanin

melancytes increase their activity when the skin is exposed to sunlight.

reveals where blood escaped from the circulation and clotted beneath the skin

a malignent tumor of the skin caused by over exposure to uv rays

• most common skin cancer
• grows very slow
• seldom metastasizes
• occurs in the stratum basale

• arises in the stratum spinosum
• if caught early and removed the overall cure rate is 99%

• the most dangerous type of skin cancer
• a cancer of melanocytes often arises from existing moles
• can metastasize very quickly
• early detection is vital

• assymetry:the 2 sides do not match
• border: the borders have indentations
• color: contains several colors (blk. brown tan blue red.
• diameter: larger than 6mm in diameter the size of a pencil eraser
• elevation: elevated above the skin surface

a benign tumor of the skin

an uncontrolled rapid growth of cells

• only the epidermis is damaged
• symptoms are redness swelling pain
• example sunburn

• injury to the epidermis and upper dermis
• symptoms like 1st degree but aslo blisters

• most serious type
• consumes the entire thickness of the skin
• a skin graft is usually needed

• temp. tattoo's only color the epidermis
• perm. tattoo color the dermis. the dermis doesnt slough off so it makes it permanent

caused by blocked sebaceous glands that have been infected by bacteria

• epidermis thins making injury happen more
• melanocytes producton declines leaving eldery pale
• sebaceous gland activity declines leaving skin dry and flaky
• sweat glands less active leaving the elderly prone to overheating
• hair follicels decline causing gray dry hair
• dermis becomes thin less collegan leads to wrinkles
• low blood supply takes longer to repair