Exam I | Integument Flashcards
What percentage of body weight is the integumentary system, and what does it include?
- 15%
- hair, skin, nails, and glands
What are the 7 functions of the integumentary system?
- protection (trauma, pathogens, radiation, chemicals)
- excretion
- water retention
- thermoregulation
- energy storage (lipids)
- vitamin D production
- tactile sensation
what are two other names for the subcutaneous layer? What are the components of this layer?
- superficial fascia, hypodermis
- adipose tissue and blood vessels
State the components of the epidermis.
- 4-5 cell layers
- primary cell types are keratinocytes, melanocytes, Lanhgerhan’s cells, and Merkel cells
What are the general characteristics of the epidermis?
- avascular
- thinner than dermis
- 50-100 cell layers, approximately the width of one sheet of paper
What does the fibrous matrix of the dermis include?
- dense irregular connective tissue
- collagen fibers
- elastic fibers
- glycosaminoglycans
what are the cells of the dermis?
- fibroblasts
- adipocytes
- macrophages
What are the general characteristics of the dermis?
- thicker than the dermis
- vascular, blood supply also diffuses nutrients into epidermis
what is the function of the dermis?
provide foundational structural support.
Briefly describe the different layers of the dermis.
- papillary dermis (most superficial)
- reticular dermis (80% of dermis)
- both are separated by the subpapillary network (rete subpapillare)
Describe the components of the papillary layer of the dermis.
- chiefly areolar tissue
- dermal papillae extend towards dermis and have capillary loops in them
- sensory structures such as free nerve endings, Meisner’s corpuscles)
Describe the components of the reticular layer of the dermis.
- irregular, dense connective tissue with extensive collagen
- abundance of fibers (collagen, elastic, reticular) generally oriented to form Langer’s lines
what is the function of the reticular layer?
confers strength (collagen) and flexibility (elastic fibers)
what is the difference between thin and thick skin?
thick skin (palms and soles) has the stratum lucidum
what is the thickest region of the skin?
reticular layer
What are 3 other names for Langer’s lines?
1) Tension lines
2) Cleavage lines
3) Kraissl’s lines
What are tension lines?
- refer to the orientation of collagen and other connective tissue fibers throughout the body
- fibers act to draw the skin “taut”
Why are Langer’s lines important?
-cutting with tension lines during surgery minimizes scarring
What are two other names for stretch marks?
stria rubra
stria distensae
Define and describe stretchmarks.
- disruption of fibrous infrastructure of connective tissue fibers
- generally perpendicular to tension lines
- may cause temporary discoloration of skin, followed by permanent (if fading) lines
- reddish coloration turns white over time
What causes stretch marks?
prolonged distension of skin. May follow growth, pregnancy, or endocrine disorders
What are the two types of melanin?
pheomelanin (pink-red)
eumelanin (yellowish to black)
What is a nevus?
dense concentration of melanocytes
Describe where and how melanin is produced.
- produced in stratum basale of epidermis, in melanosomes of melanocytes
- melanin is synthesized by tyrosine via tyrosinase
- once produced, melanosomes carries melanin into adjacent cells
What affects the production of melanin?
- uv radiation (increases)
- hormones
- skin injury
what is another name for melanosomes?
melanin granules
What are non-pigment contributors to skin color?
- hemoglobin in blood vessels (confers reddish or pinkish color)
- carotene (confers orange or yellow color)
what are the neurological/ vision consequences associated with albinism?
- nystagmus
- strabismus
- undeveloped macula
- transillumination of the eye (retina develops abnormally)
- altered optical pathway
what is the prevalence of albinism?
1 in 17,000
What are the 5 types of skin discoloration?
1) hyperpigmentation
2) jaundice
3) cyanosis
4) carotenemia
5) metallic discoloration
what is carotenemia, and what causes it?
- unusual deposition of carotene in skin
- may result from elevated intake or altered metabolism of carotene (as in diabetes or myxedema)
What causes hyperpigmentation?
- endocrine or metabolic diseases
- Addison’s or Cushing’s
What causes hyperbilirubinemia?
failure of liver and spleen to effectively recycle RBCs
What causes cyanosis?
hypoxia
What is another name for stratum basale, and why is it called that?
stratum germinativum, because highly mitotic
State the layers of the epidermis, from most superior to most inferior.
stratum corneum stratum lucidum stratum granulosum stratum spinosuum stratum basale (germinativum)
what is the structure and location of the stratum germinativum, and what cells does it contain?
- simple cuboidal layer
- rests on basement membrane
- keratinocytes, melanocytes, and stem cells
what is the function of the stratum germinativum?
serves as the source of new epidermal cells which migrate superficially
What is the stratum spinosum made up of, and what cells/structures does it contain?
- made up of layers of keratinocytes extensively linked by desmosomes
- melanosomes
- Langerhan’s cells
- dendritic cells
what is the stratum granulosum made up of?
- layers of mature keratinocytes.
- cells die as they move farther away from capillaries in dermis
what is the function of the stratum graulosum?
produces keratin and hydrophobic glycolipids that “waterproof” skin
What is the stratum lucidum made up of?
layers of squamous, dead, keratinocytes
What is the most superior layer of the epidermis in which keratinocytes are still alive?
stratum granulosum
what is the stratum corneum made up of?
- layers of defunct keratinocytes
- glycolipid layers limit water loss
what seperates the stratum basale from the dermis?
basement membrane
What determines growth rate of the epidermis?
- epidermal growth factors
- rate at which corneal cells are lost
- migration from basal layer to stratum corneum requires about 1 month
What is the most abundant cell type in the epidermis?
keratinocytes (90%)
What is the second most abundant cell type in the epidermis?
melanocytes (8%)
What is the function of keratinocytes?
- release the fibrous protein keratin
- release hydrophopic glyocolipids from lamellar granules (waterproofing skin)
How do keratinocyte layers change as they migrate to the skin surface?
go from cuboidal to squamous
Where are Merkel cells located and what do they do?
- reside near the dermis
- act as slow-adapting tactile receptors
Describe the characteristics of thin skin.
- hairy
- has sparse dermal papillae, this lower density of epidermal ridges
- relatively fewer sudoriferous glands or sensory receptors
- lack stratum lucidum
Describe the characteristics of thick skin.
- hairless
- up to 3 mm thick
- abundant sweat glands and sensory receptors, but lacks oil glands
What does the hair follicle consist of?
- external root sheath (ERS)
- internal root sheath (IRS)
- connective tissue root sheath
what is the purpose of the hair follicle?
shapes hair
how many hair follicles are on a typical human?
5 million
How do hair follicles change with age?
- cease forming after birth
- follicle density declines with age, especially on scalp
Caucasians have what kind of hair follicle shape?
round, oval
Africans have what kind of hair follicle shape?
elliptical, flat
Asians have what kind of hair follicle shape?
round, large
What is the arrector pili muscle?
smooth muscle subject to autonomic regulation
What are the 3 stages of hair growth?
1) growth (anagen) stage
2) regression (catagen) stage
3) resting (telogen) stage
Describe the anagen stage of hair growth.
- 80-90% of hairs are in this stage
- 2-7 years for scalp hair
- cell division in matrix, forcing other cells to surface
- cells progressively acquire keratin and expire
Describe the catagen stage of hair growth.
- takes 2-3 weeks
- cell division ceases
- follicle regresses
Describe the telogen stage of hair growth
- takes 3 months
- loss of hair
What is the condition of excessive hair growth on the body (including the eyelids)?
hypertrichosis
Name the sweat glands of the integumentary system.
- sebaceous (oil)
- sudoriferous (sweat): apocrine and eccrine
What are the characteristics of sebaceous glands?
- release sebum which is chiefly oil
- usually associated with hair follicles, but secrete onto skin in tarsal glands of eyes and lips as well
- absent on soles and palms
what is the purpose of sebaceous glands?
-protects hair and skin (waterproofing and prevents desiccation)
Where is carotene found?
in the stratum corneum, dermis, and hypodermis (chiefly fatty areas)
What are Langerhan’s cells?
- a type of epidermal macrophage
- immunological scavengers, provide immune protection
- is a “fixed” macrophage
- migrate from bone marrow to dermis
what happens to epidermal cells as they progressively move away from dermal capillaries?
- lose metabolic capabilities and nuclei
- become progressively more keratinized in stratum granulosum as keratin protein is assimilated into keratin intermediate filaments
What is another name for Langerhan’s cells?
Dendritic cells
Vitamin D synthesis
begins in skin, and is completed in liver and kidney
What happens in the skin in hyperthermia?
- blood flow to skin increases as capillaries dilate
- sudoriferous glands are stimulated by blood flow which leads to increased perspiration
What happens in the skin in hypothermia?
- blood flow to skin decreases as capillaries constrict
- arrector pili muscles contract
- skeletal muscles contract (shivering) to generate heat
- BMR elevated via release of adrenergics and thyroid hormone
What do eccrine and apocrine glands secrete?
- eccrine secrete water, electrolytes, and nitrogenous wastes
- apocrine glands secretions have high fat content, which is metabolized by bacteria causing B.O.
where are eccrine and apocrine glands located?
- eccrine glands are abundant, especially on palms and soles
- apocrine glands are chiefly in axillary and urogenital regions
What is the difference in eccrine and apocrine method of secretion?
- eccrine glands secrete directly onto skin
- apocrine glands extend form the dermis through a duct near the hair follicle
What stimulates eccrine and apocrine gland secretion?
- eccrine respond to sympathetic activation to lower skin temperature, or as a response to stress
- apocrine respond chiefly to stress
NMSC
non-melanoma skin cancer
What skin cancers are caused by UV radiation?
- basal cell carcinoma (BCC)
- squamous cell carcinoma (SCC)
What is the relationship between wavelength (frequency) of a sun ray and energy?
inverse
uVA
- photoaging
- oncogenic (as it reaches basal layers of dermis)
- tanning beds
- 95% of total uV radiation reaching surface
- deepest penetrating ray (long wave)
uVB
- erythema and sunburn
- intensity varies with season and time
- oncogenic
- 2nd deepest penetrating ray (medium wavelength)
uVC
- short wavelength
- largely reduced by ozone layer
What 4 things can cause a burn?
- heat
- extreme cold
- chemicals
- radiation
How are burns classified?
- by depth of skin affected
- depth of skin determines what degree burn is
partial thickness burns
- painful
- 2nd degree burns
full thickness burns
- -3rd degree burn
- epidermis and dermis destroyed, damages hypodermis
- tend to destroy nerve fibers
- do not heal, usually necessitate skin grafts
4th degree burn
involves hypodermis, muscle, and bone
2nd degree burns
- aka partial thickness burns
- epidermis destroyed, dermis damaged
- can be superficial or deep
Rule of Nines
- burn of anterior and posterior lower limbs is 36%
- burn of anterior and posterior trunk is 36%
- anterior and posterior upper limbs is 18%
- anterior and posterior head and neck is 9%
- perineum is 1%
When are burns considered critical?
- if over 25% of the body has 2nd degree burbs
- if over 10% of the body has 3rd degree burns
- if there are 3rd degree burns on face, hands, or feet
Utricharia
hives (red, itchy eruptions)
what is another name for spider veins?
telangiaectasis
What contributes to spider vein formation?
-genetics and aging
acne vulgaris
- affects 80% of adolescents
- generally associated with blocked release of sebum
- bacterial action on sebum tends to aggravate inflammation
psoriasis
- chronic inflammatory condition
- epidermal plaques form as cells rapidly proliferate
- highly diverse variable presentation
- aggravated by environmental “triggers”
Warts
- infection by HPV, a DNA virus
- contagious- by direct contact or surface contamination
- tend to regress without treatment over several months or years
BCC
- cells of stratum basale proliferate into hypodermis and dermis
- most common type of skin CA, least malignant (treated surgically with 99% success)
- tends to grow slowly. May appear as “shiny dome” or as ulcerating nodules
SCC
- chiefly involve spiny layer (stratum spinosum) cells
- kills 5,000 Americans annually
- typically on scalp, ears, or lower lip
- can rapidly spread to lymph nodes
- scaly red patches or sores that may crust or bleed
melanoma
- most lethal, but rarest skin CA
- tend to appear spontaneously. 1/3 develop from pigmented moles
- highly metastatic, resistant to chemotherapy
