Integument and Barries to Infections Flashcards
What is the largest organ in the body?
integument
What are the two components of the integumentary system?
skin and epidermal derivatives (skin, hair, sweat glands, sebaceous glands, and mammary glands)
What are the three layers of the integumentary system?
epidermis (ectoderm) , dermis (mesoderm), and hypodermis
What is thick skin?
it is thick
>5mm
-palms of head and soles of feet
What is thin skin?
thinner
1-2 mm
General functions of integumentary system?
-protection
-water barrier
-thermoregulation
-metabolic function
-sensation
What makes finger prints?
epidermal ridges and underlying dermal papillae
What causes tension lines?
arrangement of collagen fibers in the dermis
What is the epidermis?
outer layer of skin
-from the ectoderm
-have ability to regenerate
-stratified squamous, keratinized epithelium
What the five layers of epidermis form superficial to deep?
-stratum corneum
-stratum lucidum
-stratum granulosum
-stratum spinosum
-stratum basale
What allows the epidermis and dermis to be held together?
epidermal interpapillary peg and rete ridges interlock with the dermal ridge
What does the dermal papillae do?
project upward into the epidermal layer
-found in thick skin
what are the cells of the epidermis called?
keratinocytes
-keratinized, stratified squamous epithelium
Is there blood flow to the epidermis?
no
-the blood vessels do not penetrate the basement membrane
What supplies the epidermis? (blood)
blood vessels in the dermis
What are the two layers of the dermis?
papillary and reticular layer
characteristics of papillary layer of dermis:
-dense irregular CT
-damage to elastic fibers as you age
-pegs connect to the epidermis
-basal keratinocytes anchor to basement membrane
-add strength
-highly innervated and vascularized
What is in the reticular layer of dermis?
collagen bundles and coarse reticular fibers for support
Where are hair follicles, sweat and sebaceous glands?
in reticular layer of dermis
What are the thick collagen bundles and elastic fibers in reticular layer?
langer lines
What type of incisions have less scarring?
incisions parallel to langer lines
What is Bullous pemphigoid?
acute or chronic autoimmune skin disease involving the formation of blisters at the space between the dermis and epidermis
What is attacked in Bullous pemphigoid?
dystonin and/or type XVII collagen
-both associated with hemidesmosomes
What is the subpapillary plexus?
blood supply in skin at the junction of papillary and reticular layers
What is the cutaneous plexus?
blood supply in skin and the junction of reticular layer and hypodermis
What is the subcutaneous plexus?
blood supply in skin located deep in the hypodermis
Characteristics of stratum basale:
cuboidal or columnar
-rest on basement membrane
-lots of hemidesmosomes
-mitotic figures
Characteristics of stratum spinosum:
flattened polygons
-oval nuclei
-lots of desmosomes
-spine like cell processed (prickle cells)
Characteristics of stratum granulosum:
-flattened cells, flattened nuclei
-basophilic keratohyaline granules
-granules have involucin that interaction with cytokeratin and produce protein keratin
-increased tight functions
What initiates keratinization?
release of lysosomal enzymes that come from rupture of keratohyaline granules and polymerization of their contents
What does lyozyme do to cells?
kill them
Where are keratinosomes?
cells of granular layer that have membrane bound lamellar structures
What do keratinosomes do?
contain glycolipids and provide waterproofing coat for skin cells
Characteristics of stratum lucidum:
keratinocytes have no nuclei
-intermediate layer between granulocytes and stratum corneum
-form barrier to water
-found in thick skin
Characteristics of stratum corneum:
-keratinocyte are flattened, no nuclei (squames)
-contain keratin filaments
-aid in permeability barrier, prevents desiccation
-continuously exfoliated
What are melanocytes?
neuroectodermal dendritic cells in epidermis
-usually restricted to basal layers
What do melanocytes make?
melanin (skin pigment)
Where is melanin released from?
melanosomes inside melanocytes
Steps melanocytes take during sun exposure:
-when skin is exposed to UV radiation, melanocytes send more melanin to the surface of the skin
-melanin directly absorbs UV rays and attempts to prevent the skin from burning
-as more melanin accumulates, the skin tans or freckles
When does a sunburn occur?
when the skin cannot produce melanin quickly enough to prevent the UV rays from injuring blood vessels close to the skin’s surface
What is eumelanin?
(dark brown/black pigment)
-present in dark haired individuals
What is pheomelanin?
(red to yellow pigment)
-present in individuals with red or blond hair
What causes the differing skin tone in people?
the rates of melanin production and degeneration by lysosomal enzymes
-NOT the number of melanocytes
What is vitiligo?
autoimmune disease
-destruction of melanocytes
-depigmentation
What controls melanin synthesis?
melanocyte stimulating hormone
What is the process of producing melanin?
tyrosin precursor first oxidized to DOPA by tyrosinase
-conversion of DOPA to melanin in melanosome
What do albinos not have?
tyrosinase
What is MITF?
microphthalemia associated transcription factor
-regulate the differentiation of melanocytes
-lack of MITF = ocular albinism type 1
-excess MITF associated with melanoma
What are langerhans cells?
phagocytic, involved in immune responses
-travel to lymph nodes and then interact with T cells
-antigen presenting cells
-monitor foreign antigen that contact epidermis
Where are langerhans cells?
in stratum spinosum
What is psoriasis?
inflammatory skin disorder
-initiated by Langerhans cells
-excess proliferation of epidermal keratinocytes from stratum basale to stratum corneum
-increased inflammatory cells
-angiogenesis occurs
-stratum corneum thickens and form plaques
What are retinoids?
steroid-free alternative in wide range of skin disorder including acne photoaging, post-inflammatory hyperpigmentation, and psoriasis
Where are the nerves and blood vessels of skin?
hypodermis
What is dermatitis?
eczema
-inflammation of the skin
-itchy, erythematous, vesicular, weeping, and crusting patches
What is the cause of dermatitis?
unclear
-possible dysfunctional interplay between the immune system and skin
Common skin tumors
-squamous cell carcinoma
-basal cell carcinoma
-melanoma
What type of skin tumors are from epithelial cells?
squamous and basal cell
What type of skin cells cause melanoma?
melanocytes
What is squamous cell carcinoma?
-nests in squamous epithelial cells arising from the epidermis and extending into the dermis
-eosinophilic cytoplasm and a large, often vesicular, nucleus
What is basal cell carcinoma?
aggregates of basal cells with a cytoplasm and large, hyperchromatic nuclei, apoptotic cells, and all included in a fibromyxoid stoma
What is melanoma?
pagetoid spread of melanocytes with variable size and shape, melanoctyes with lymphovascular spaces, deep and atypical mitosis and increased apoptosis
What is first intention healing?
from a clean (surgical) approximated incision
-incision immediately fill with blood and clots
What is the acute phase of wound healing?
3-24 hours
neutrophils infiltrate the clot
When does epithelial closure happen?
24-48 hours
-epithelial cells of stratum basal begin mitosis
What happens during day 3-7 of wound repair?
neutrophils being to be replaced by macrophages
What happens around day 5 of wound repair?
incision filled with granulation tissue
What happens in week 2 of wound repair?
continued fibroplasia and collagen accumulation
-mature granulation tissue
-progressive decrease in inflammation
-cause itch when healing
What happens in month 2 of wound repair?
connective tissue scare, without inflammation, covered by intact epithelium
collagen breaks down and old scars can reopen and bleed
What are keloids?
excess fibroplasia
-raised, thickened connective tissue scar
What is second intention healing?
occurs with more extensive loss of tissue, where wound edges do not approximate
What is the migration time of epithelial cells of stratum basale?
0.5 mm/day
How long does it take to fill a 1 cm wide cut?
3 weeks
How long does it take for cells to mature from stratum basal to stratum corneum?
25 days
How long does it take for scabs to lift from the periphery?
around 3 weeks
What causes wound contraction?
myofibroblasts
What type of burns require grafting?
third degree burns
What do 1st degree burns affect?
involve only epidermis
What do 2nd degree burns affect?
involve both epidermis and dermis
What do 3rd degree burns affect?
involve all three layers: epidermis, dermis, and hypodermis
What do exteroceptors sense?
external environment
What do proprioceptors sense?
position and movement of the body
What do interceptors sense?
internal organs
What do mechanoreceptors sense?
stretch, vibration, and mechanical deformation
What do thermoreceptors sense?
respond to cold or hot
What do nociceptors sense?
response to pain
What are Meissner corpusles?
present in dermal papilla
-tactile receptor
-cylindrical structures
-afferent nerve fibers associated with minimally modified Schwann cells
What are peritrichial nerve ending?
nerve fibers wrapped around the base of the hair follicle
-stimulated by hair movement
What are Merkel cells?
neural crest cell derived cell in basal layer of epidermis
-tactile receptor
-look like melanocyte
-store serotonin in dense core granules
-have pressure sensitive mechanoreceptors
What are free nerve endings?
Lack myelin or Schwann cells
-respond to pain and temperature
What are Ruffini end organs?
respond to stretching
-in skin and joint capsule
-dermal mechanoreceptors in soles of feet
What are Pacinian corpusle?
sensitive to pressure and vibration
-found in hypodermis and deep fascia tissues
-large ovoid structures
-in fingerprints and around joint
-affect nerve fibers with highly modified Schwann cells
-form concentric lamellae
Where are free nerve endings?
epidermis and papillary dermis
-surround most hair follicles
What glands are associated with hair?
sebaceous glands
What smooth muscle bundles are associated with?
arrector pili
What covers the shaft of hair?
thin cuticle of overlapping keratin plates
What do large hairs have?
central medulla
What is it called with the arrector pili muscles contract and cause goose bumps?
piloerection
What causes piloerection?
sympathetic stimulation
What is the function of hair in mammals?
thermoregulation
as well as a display of color and shape
What are the three phases of hair growth?
anagen (long phase of active growth)
catagen (short phase of involution)
telogen (short inactive involuted phase)
What is exogen?
shedding of old hair shaft
What is vellus hair?
thin body hair of children
What is terminal hair?
the hair that replaces vellus hair after puberty
Where does hair form?
in the stratum basale of epidermis
What must interact for hair formation?
hair germ cells and fibroblasts from dermal papilla
What makes up the hair shaft?
medulla and cortex surrounded by cuticle
What forms the internal root sheath?
hair bulb
What forms the external root sheath?
epidermis
What is a glassy membrane?
modified basement membrane
-separates hair bulb from surrounding dermis
Where is the hair follicle rooted?
in dermis
What is androgenic alopecia?
most common form of hair loss
30-40% of adults
-affected adults have high levels of 5 alpha reductase
What does 5-alpha reductase do?
convert testosterone to dihydroxytestosterone
What are cutaneous horns made of?
keratin
what covers the proximal nail bed?
epithelium
-eponychium
What is the cuticle of nail?
thick corneal layer of eponychium extending on the dorsal surface of nail plate
What is the hyponychium?
union between nail bed and the nail plate at the end of the fingertip
What is it called when the hyponychium is disrupted and fungus invade?
onychomycosis
What corneocytes?
cells that make up the nail plate and do not have nuclei or organelles
What causes the hardness of the nails?
high sulfur matrix proteins
What is the nail bed?
the ventral surface of the nail plate
What is the nail plate?
flattening of epidermal cells, nuclear fragmentation, and condensation of cytoplasm to form horny cells
What is normal nail growth length?
0.1 - 1.2 mm per day
What skin layer is missing in nail plate?
stratum granulosum
Do fingernails or toenails grow faster?
fingernails
What is the nail root?
the proximal end of nail
-extends into dermis and attached to periosteum of distal phalanx
Where does nail growth occur?
epithelium of nail root in germative zone of nail matrix
What are sebaceous glands?
associated with hair follicles
-produce sebum which is a lipid rich substance that is oily
-holocrine secretion
Where is sebum secreted?
pilosebaceous canal
What is seborrhea?
excessive secretion of sebum
What is a pilosebaceous unit?
each hair follicle and associated arrector pili muscle and subaceous gland
What are eccrine/merocrine sweat glands?
coiled tubular glands
-long ducts with cubodial epithelium that empties into a sweat pore
-merocrine secretion
What are apocrine sweat glands?
located in specialized areas and empty into a hair follicle
Merocrine glands secrete…
only product
Apocrine glands secrete…
product and some cytoplasm
(adrenergic)
location of merocrine glands
over most of the body except lips and genetalia
location of apocrine glands
axillae groin
(develop at puberty)
What do apocrine glands contain?
proteins, carbs, ammonia, lipids, and organic products
-odorless when secreted. when broken down cause odor
What type of glands secrete things that serve as sexual attractant?
apocrine
What is cerumen?
ear wax
Where are ceruminous glands?
external auditory meatus (these are modified apocrine glands)
On average, how much does the body lose a day due to evaporation from lungs, skin, and mucous memrbanes?
600 ml/day
