integumentary system

the integumentary system

comprised of the skin, hair, and nails

skin

largest organ of the body, made up of the epidermis, dermis, and hypodermis

epidermis

outer layer, made of stratified squamous epithelium, avascular (no direct blood flow), recieves nutrients from the basement membrane

four layers of the epidermis

stratum corneum, stratum granulosum, stratum spinosum, and stratum basale

stratum basale

bottom layer of the epidermis, adhered to the basement membrane, constantly dividing to rebuild the skin

epidermal ridges

formed by the stratum basale, also called fingerprints, are unique to each person and consistent through life

cells found in the epidermis

keratinocytes, Langerhans cells, fibroblast cells, melanocytes, and Merkel cells

langerhans cells

act as a first lie of defense, identifying microorganisms before reaching the bloodstream

merkel cells

sensory receptor that responds to light tough

fibroblast cells

produce collagen which adheres the epidermis cells together and give the skin elasticity, supports the tissue matrix of wounds until new cells are developed

dermis

middle layer, contains sweat glands, oil glands, and sensory organs, has a high water content

papillary region

superficial layer of the dermis, contains collagen fibers and elastic fibers

reticular region

deep layer of the dermis, contains collagen fibers and elastic fibers, contains the skins main blood supply

contusion

a bruise, damage of a blood vessel in the skin

hypodermis

inner layer, also called subcutaneous, made of mostly fat cells (adipocytes), anchors the dermis to a layer of fat cells

skin cells

absorb ultraviolet light to produce vitamin D, contains sensory receptors and glands for protection from pathogenic microorganisms and temp changes

lymphatic system

protects the body is foreign objects and microbes that get into the body due to integumentary system damage

merkels cells and meissners corpuscles

mechanoreceptors that detect sensory info by way of light touch and vibration

nociceptors

detect pain, like from a pin prick

pacinian corpuscles

detect mechanical sensory info based on pressure applied to the skin

thermoreceptors

detect hot and cold

exocrine glands

release secretions through a duct into an epithelial surface or lining

multicellular glands

set within epithelial tissue and release contents through a duct to the surface

sebaceous glands

(oil glands) produce sebum to keep the hair and skin from drying out and inhibits the growth of harmful microorganisms

sweat glands

(sudoriferous glands) produce sweat in almost every part of the skin

dermatome

a region of skin innervated by one sensory nerve, sends sensory nerves to the spinal nerve, then the spinal cord, then other the brain for processing

hair

made up of dead epidermal cells that have been converted to keratin

hair root

begins at the hair bulb which has a blood and nervous supply in the dermis

hair shaft

extends through the epidermis to the outside

arrector pili muscle

a smooth muscle on each hair follicle that contracts when the body is cold or experiences emotional responses

nails

composed of dead epidermal cells that have been converted to keratin

nail body

visible portion of the nail, covering the epidermis called the nail bed

cuticle

the stratum corneum of the epidermis that extends from the nail root, covering some of the visible portion of the nail

lunula

visible portion of the nail bed near the nail root

tissues

cells that come together, comprised of cells and a matrix

matrix

(extracellular material) made up of ground substance, protein, and collagen

clot

blood platelets accumulate at the damage site to form a mesh like substance and prevent blood loss

mast cells

release histamine to dilate blood vessels to bring more blood and nutrients to the damage site, initiate an inflammatory response

macrophages

engulf and destroy disease-causing pathogens

scar

an overgrowth of the fibrous connective tissue that cannot be fully replaced, caused when the wound is too deep, some of the original function is lost

first degree burn

only damage the epidermis, becomes dry, red, and painful, eg: sunburn

second degree burn

damages the epidermis and some of the dermis, turns red and forms blister, is painful and swollen due to damage to the sensory organs in the dermis

third degree burn

damage the epidermis, dermis, and possibly the subcutaneous layer, typically becomes white and possible “charred”, extremely painful

fourth degree burn

damages the epidermis, dermis, hypodermis, and some of the tissue such as a muscle or bone, no sensation due to destroyed nerve endings, may require a skin graft