Integumentary System

integumentary system characteristics

largest organ we have, includes skin, hair, glands, nails, and subcutaneous tissue

integumentary system functions

protection (regulates barrier between internal and external environment, protects against UV, bacteria, and fluid loss), sensation, temperature regulation, vitamin D production, excretion

epidermis

outermost layer, made up of epithelial tissue that is avascular and innervated

dermis

fibrous connective tissue that is vascular, used for protection and structural strength, sits above subcutaneous tissue

hypodermis/subcutaneous tissue

made up of loose, adipose tissue, protective

cell types in epidermis

keratinocytes, melanocytes, epidermal dendritic cells (Langerhan’s), Merkel/tactile cells

keratinocytes

cell that produces keratin, primary cell of epidermis

melanocytes

produce melanin that gives us pigment, in stratum basale, transfers melanin to keratinocytes

epidermal dendritic cells/langerhans

function as macrophages for immune function, form continuous network

tactile/merkel cells

in epidermis, used for touch with sensory nerve endings

layers of epidermis

stratum basale, stratum spinosum, stratum granulosum, stratum lucid, stratum corneum

stratum basale

deepest layer made up of single layer of cuboidal or columnar cells, anchored to hemidesmosome, incredibly fast mitosis rate, gives rise to keratinocytes

stratum spinosum

second deepest layer made of weblike network of keratinocytes and formation of lamellar bodies

lamellar body

little sac of fat

stratum granulosum

3-5 cell layers thick where cells begin to flatten out and keratohyaline and lamellar bodies release lipid to reduce water loss

stratum lucidum

fourth layer that is clear and made up of flattened, dead keratinocytes; layer only occurs in thick skin

stratum corneum

final layer 20-30 cells thick filled with keratin and glycoproteins protect against abrasion and loss of water

melanocyte

produces melanin and despots it into a mnelanosome, found in basal layer, stimulated by sunlight, protects DNA from UV

laters of dermis

papillary and reticular

cells of dermis

fibroblasts, macrophages, mast cells, white blood cells

structures of dermis

nerves, blood vessels, hair follicles, lymphatic vessels, smooth muscle

papillary layer

thin, superficial layer of dermis containing blood vessels and meissner’s corpuscles with papillae that project into epidermal layer

reticular layer

layers that makes up most of dermis, made of dense irregular connective tissue and made up of collagen and elastin fibers to withstand much tensile force and recoil in all directions

cleavage layers

map of elastic and collagen fibers oriented in specific patterns

intradermal tissue

injection though epidermis

subcutaneous tissue

injection into subcutaneous layer

intramuscular injection

injection into muscle

lanugo hair

sheds quickly, delicate and unpigmented, found in newborns/fetuses

terminal hair

adult hair, long, coarse, pigmented on scalp, eyelids, facial, pubic

vellus hair

hair everywhere else, fine and short

hair shaft

hair that sticks out of root, above skin surface

hair root

part of hair structure below skin surface

hair papilla/dermal papilla

finger-like projection at very base of hair follicle with tiny artery and vein that supplies blood and nutrients for hair growth

glands of the skin

sebaceous gland, aprocrine sweat gland, eccrine gland

sebaceous gland

creates oil (sebum) that is secreted to moisturize and waterproof hair and skin

eccrine sweat gland

type of merocrine gland that is coiled, tubular, but penetrates to surface; found in places with not much hair (palms and feet), used for temperature regulation

apocrine sweat gland

coiled and tubular, produces sweat, has large ducts that empty into hair follicle, found in hair, genitalia, becomes active during puberty and turned on by sex hormones