Chapter 4- Integumentary System Flashcards
2 components of the integumentary system
- cutaneous membrane
2. accessory structures
Cutaneous membrane divided into..
epidermis
dermis
Ex. of accessory structures
- hair
- nails
- glands
Functions of Integumentary system
- protects deeper tissues from damage (mechanical, chemical, bacterial, desiccation, etc)
- aids in heat regulation
- airds in excretion of urea and uric acid
- synthesizes Vitamin D
Epidermis Characteristics
- stratified squamous epitherlium
- lacks blood vessels but can divide
- as new cells divide, push older ones to surface
- outer most layers are dead
Epidermal cell types
keratinocytes
melanocytes
langerhan cells
merkel cells
Keratinocytes
- epidermal
- 90% of cells
- produce keratin
- provide protection
melanocytes
~8% of cells
- produces melanin pigments which protect against UV radiation
- melanin transferred to other cells with long cell processes
langerhan cells
- from bone marrow
- part of immune response
merkel cells
- in deepest layer
- form touch receptor with sensory neuron
What cells are produced at the basal lamina
keratinocytes by stem cells
what happens after keratinocytes are made
they are pushed towards surface
- fill with keratin and oils
- slowly die
- 4 week journey
layers of epidermis
- stratum germinativum
- stratum spinosum
- stratum granulosum
- stratum lucidum
- stratum corneum
Stratum germinativum
- deepest single layer of cells
- combination of merkel cells, melanocytes, keratinocytes and stem cells
How do stratum germinativum attach to basal lamina
desmosomes and hemidesmosomes
stratum spinosum
- 8-10 cell layers held together by desmosomes
- melanin taken in by phagocytosis from nearby melanocytes
- during slide prep, cells shrink and look spiny
stratum granulosum
3-5 layers of flat dying cells
-show nuclear degeneration
what does stratum granulosum contain that are important for dessication?
contains dark staining keratohyalin granules
-release lipid that repels water
stratun lucidum
- seen in thick skin on soles and palms of feet only
- three to 5 layers of clear flat dead cells
stratum corneum
25-30 layers of flat dead cells filled with keratin and surrounded by lipids
- continuously shed
- barrier to heat, light, water, chemicals and bacteria
what layer do callus’s form on and what causes them?
stratum corneum
-friction
Thick skin
- palmer and planter surface
- about 30 layers of S. corneum
- all 5 layers
thin skin
rest of body surfaces
- fewer layers of S. Corneum
- no S. lucidum
epidermal ridges
- stratum germinativum forms ridges that extend into the dermis
- increases area of contact for better grip
where is melanin produced
epidermis by melanoctes
melanin
same number of melanocytes in everyone but varying amounts of pigment
- melanin production is in response to melanin stimulation hormone
- UV in sunlight increases melanin production
what gets converted to melanin
melanocytes convert tyrosine
different types of melanin
- eumelanin-brown or black melanin
- pheomelanin-red brown version
What are freckles or liver spots
melanocytes in a patch
mole
benign localized overgrowth of melanocytes (nevus)
albinism
inherited lack of tyrosinase; no pigment
2 other skin pigments
- carotene
- hemoglobin
carotene
- dermis
- yellow-orange pigment (precursor of vit A)
- found in stratum corneum and subcutaneous
Hemoglobin
- red, oxygen carrying pigment in blood cells
- no other pigments present, epidermis is translucent so pinkness evident
how many layers in dermis
2 layers
- papillary layer
- reticular layer
papillary layer
areolar CT
- capillaries and neurons
- dermal papillae
reticular layer
- anchoring layer
- large vessels, nerves, adipocytes, arrector pili muscle
- dense irregular CT
- ->collagen; strength
- ->elastic: strength, flexibility
2 things that supply blood to the skin
- cutaneous plexus
- papillary plexus
cutaneous plexus
- network of arteries and veins supplying skin
- in subcutaneous layer
papillary plexus
- follows epidermal/dermal boundary
- helps nourish epidermal layer
stretch marks
- weight gain causes fibers to stretch (break)
- form due to decrease in fiber elasticity and tear
Hypodermis
- superficial fascia/subcutaneous layer
- made of areolar and adipose CT
- collagen and elastic fibers
- no distinct boudary in dermis
- adipose=insulator
- stabilizes skin
accessory structures: hair
- on most surfaces except plantar/palmer, parts of digits, lips, eyelids
- hair number fixed at birth
3 types of hair
- vellus-peach fuzz
- terminal-thicker with darker pigment
- intermediate-arms
Hair consists externally of..
- shaft (above skin)
- root(deep into dermis)
- bulb(base of follicle)
hair consists internally of..
- cuticle (outermost portion)
- cortex (middle portion)
- medulla (innermost portion)
Functions of Hair
- protection
- reduction of heat loss (eh)
- sensing light touch (YES)
Root hair plexus
- sensory nerves surrounding follicle
- detect light touch
- detect hair movement
Arrector Pili
- smooth muscle
- moves hair
- causes goose bumps
3 stages of hair growth
- anagen stage
- catagen stage
- telogen stage
anagen stage
- lasts from 2 to 6 years depending on body part
- matrix cells at base of hair root producing length
catagen stage
- lasts up to 2 weeks
- matrix cells inactive & follicle atrophies
telogen stage
- hair follicle remains dormant
- hair is eventually pushed out by new hair as cycle renews
hair color is result of..
melanin produced in melanocytes in hair bulb
2 types of hair color melanin
eumelanin-brown/black (large amounts, blonde is little)
-pheomelanin-red hair
4 exocrine glands of skin
- sebaceous (oil)
- sudoriferous (sweat)
- ceruminous (wax)
- mammary (milk)
oil gland
sebaceous
sweat gland
sudoriferous
wax gland
ceruminous
milk gland
mammary
sebaceous gland
- secretes sebum by holocrine secretion
- sebum decreases evap and decreases bacterial growth
2 types of sebaceous gland
- with hair: sebum into follicle
- w/o hair: sebum into epidermis
sudoriferous glands
- coiled tubular gland
- sweat released by merocrine secretion
- neural control
2 types of sedoriferous gland
- apocrine
- eccrine
Eccrine sweat gland
- greatest on palm
- not associated with hair follicle
- sensible persperation (water, NaCl, urea)
- cooling, excretion, protection
Apocrine sweat glands
- not actually apocrine
- assoc. w/hair follicles
- located in axillae/groin
- viscous secretion from puberty
- reduce friction, cooling, secrete phermones
modified apocrine sweat glands
- mammary-milk
- ceruminous-external ear (secretion mixes with sebum=ear wax)
Nail structure
- nail body
- nail bed
- nail root
- lunula
nail body
keratinized, plate-like structure
nail bed
-surface of skin that covers nail body
nail root
source of nail production
lunula
whitish, half moon region at base of nail plate
what are burns
tissue damage & cell death caused by heat, electricity, UV radiation or chemicals
associated dangers of Burns
- dehydration
- electrolyte imbalance
- circulatory shock
first degree burn
skin red and swollen, only damaged epidermis
second degree burn
skin red with blisters; epidermis and upper dermis damaged
third degree burn
gray-white or black; destroys entire layer
critical burns
- 25% of body has 2nd degree
- 10% of body has 3rd
effects of aging
- less hair
- reduced blood supply
- dermis thins
- drying of epidermis
- fewer melanocytes
