Ch 6 The Integumentary System Flashcards
What does the integumentary system consist of?
skin + sweat and oil glands, arrector pili muscles, hairs, and nails
What is the main function of the integumentary system?
barrier between us and the outside world
What are the 5 other functions of the integumentary system?
1) regulation of body temperature
2) retards water loss from tissues
3) houses sensory receptors
4) synthesizes biochemicals
5) excretes small amounts of wastes
What are the 2 main regions of skin?
epidermis and dermis
What is the “extra” layer that lies near the skin but is not part of the skin?
hypodermis
What is the epidermis?
- made of keratinized stratified squamous epithelium
- outermost shield of body
- avascular (no blood)
- 4 or 5 distinct layers + 4 cell types
What is the dermis?
- underlying tissue
- tough, made of fibrous connective tissue
- separated from epidermis by basement membrane
- second skin region, dense irregular tissue
- strong, flexible connective tissue
- binds body together
- rich blood supply transfers nutrients to epidermis
- lymphatic and nerve supply, has muscle
What is the hypodermis?
- subcutaneous tissue just below the skin
- not really skin, but closely related
- adipose and areolar connective tissue
- acts as shock absorber and insulator
- contains blood vessels to help supply skin and underlying adipose
What are the 4 epidermis cell types and their functions?
1) keratinocytes - make keratin, protective
2) melanocytes - make melanin for skin color
3) Langerhans’ cells - macrophages vs. microbes that invade skin; damaged by UV
4) merkel cells - sensory reception for touch in conjunction with sensory neuron
What are the 5 layers of epidermis and their characteristics?
1) stratum corneum - made of about 30 layers of tightly packed dead cells = keratin for protection
2) stratum lucidum - only in thick skin, clear
3) stratum granulosum - thin, middle layer, flattened keratinocytes + lamellar granules - secrete lipid rich waterproofing
4) stratum spinosum - mostly keratinocytes
5) stratum basale - attached to underlying dermis, melanocytes = 25% of cells here, nourished by blood vessels of dermis, single layer of cuboidal/columnar cells, connected to each other and stratum spinosum by desmosomes (cellular “staples”), divide readily
What is the difference between thin and thick skin?
thick - palms, fingertips, soles of feet; has all 5 layers (strata), including stratum lucidum
thin - everywhere else; 4 layers - no stratum lucidum
What are 4 functions of the epidermis?
- prevents water loss
- prevents mechanical injury
- shields against harmful chemicals
- melanin absorbs UV radiation in sunlight to prevent DNA mutations
What is melanin?
the pigment largely responsible for skin color
What is melanin controlled by?
genetics - genetic code tells melanocytes how much and what color melanin to produce
What does more melanin do?
makes skin darker
What does less melanin do?
makes skin lighter
True or False: The number of melanocytes is the same in everyone.
True
What are 4 other factors that affect skin color?
- exposure to sunlight, sunlamps, x rays
- blood in vessels (seen in light skin people only)
- diet - lots of orange veggies contain carotene which turns skin orange
- metabolic problems - jaundice turns skin yellow
What does high and low oxygen blood do?
high = pink skin
low = blue skin - cyanosis
What are newborns with jaundice treated with?
bili lights
What is psoriasis?
- keratinocytes divide more quickly than normal
- move from basale to corneum too rapidly
- cells shed in 7-10 days and are filled with abnormal keratin
- appear as silvery scales on knees and elbows
What are the 2 layers of the dermis?
papillary and reticular
What is the papillary layer?
- Meissner’s corpuscles (touch receptors)
- dermal ridges due to papilla (little cone shaped projections)
- soles and palms
- create ridges in epidermis
- form fingerprints due to sweat collecting there
What is the reticular layer?
- thick collagen fibers
- Pacinian corpuscles (deep pressure receptors)
- sweat glands, hair follicles
