integumentary Flashcards
organs of integumentary system
- skin (epidermis, dermis, hypodermis)
- glands (sweat and sebaceous)
- hair
- nails
layers of the skin and their function
outer to inner
EPIDERMIS - gives the skin its colour by the pigment called melanin
- thin cellular layer
- keratinized stratified
squamous epithelium
DERMIS - has fibroblasts, connective tissue and responsible for secreting collagen 4 and elastic fibers
- thick fibrous layer
HYPODERMIS - aka subcutaneous layer. the fat layer (mainly adipose tissue) and insulation (another function)
- attaches the skin to underlying tissues and organs
- contain lamellated corpuscles which detect external pressure applied to skin
external factors that affect the skin
heat and cold
chemicals
infection
trauma or friction
internal factors that affect the skin
psychological genetic internal disease drugs infections
4 major types of cells in the EPIDERMIS
- Keratinocytes (largest population) produce keratin which is a tough fibrous protein that provides protection
- Melanocytes (have melanin granules): which produce the pigment melanin that protects against damage by ultraviolet radiation
- Langerhans cells: involved in immune responses, arise from red bone marrow
- Merkel cells: function in the sensation of touch along with the adjacent tactile discs
the 5 major layers of EPIDERMIS
thin skin has 4 layers, thick skin has all 5 layers - 5th layer only in thick is stratum lucidum
- Stratum basale (deepest layer) or stratum germinativum, where continuous cell division occurs which produces all the other layers
- Stratum spinosum, 8-10 layers of keratinocytes (little spines on the layer)
- Stratum granulosum, which includes keratohyalin and lamellar granules
- Stratum lucidum is present only in thick skin (the skin of the fingertips, palms, and soles) (quite pale)
- Stratum corneum: composed of many sublayers of flat, dead keratinocytes called corneocytes or squames that are continuously shed and replaced by cells from deeper strata; constant friction can stimulate formation of a callus.
keratinisation
the accumulation of more and more protective keratin, occurs as cells move from the deepest layer to the surface layer
describe the outer papillary region and deeper reticular region of the DERMIS
OUTER PAPILLARY REGION -
- areolar connective tissue containing thin collagen adn elastic fibers
- dermal papillae (includes capillary loops)
- corpuscles of touch
free nerve endings
DEEPER RETICULAR REGION -
- dense irregular connective tissue
- has adipose cells, hair follicles, nerves, sebaceous and sweat glands
which lines in the dermis layer indicate the direction of collagen fibers?
Langer’s lines
what are EPIDERMAL RIDGES in the dermis layer?
- reflect contours of underlying dermal papillae
- basis for fingerprints and footprints
- increase firmness of grip by increasing function
what is a nevus/mole?
A benign localized overgrowth of melanocytes
function of hair (Hair is composed of dead, keratinized epidermal cells)_
- protection
- reduction of heat loss
- sensing light touch
structure of hair (out to in)
- shaft which mostly projects above the surface of the skin
- root which penetrates into the dermis
- hair follicle
- epithelial root sheath
- dermal root sheath
muscle responsible for movt of hair
erector pili - located near the roots
name the 2 types of sweat (sudoriferous) glands
ECCRINE
- cool the body by evaporating
APOCRINE
- located in the skin of axilla, groin, areolae, bearded facial
- excretory ducts open into hair follicles
