integumentary Flashcards
where do the cells of the epidermis origniate
in the basal layer
what is the basal layer made up of
cuboidal, nucleated, highly active epithelial cells
as new cells are formed, they are pushed upwards, away from the basal layer and change their shape and structure. by the time they have reached the skin surface, what has been re[;aced withn the cells and what has it been exchanged with
cytoplasms is replaces with a proteoin called keratin
how long does complete replacement of the epidermis usauslly take
around a month
hairs, secretions from sebaceous glans and ducts of sweat galnds pass through the what to reacj the skin surface
pass through the skin surface
what anchers the dermis securely to the epidermis
the dermal papillae
when trauma separates the dermis what develops
blisters
by the dermis being securely attached to the epidermis what does this allow for
for the passage and echange of nutrients and wastes to the lower part of the epidermis
where the skin is subject to greater tear, will the epidermis be thinner or thicker
thicket
in areas of a thicker epidermis, what gives the skin surface an riged appearance
dermal papo;;ae arranged in parallel lines, giving the skin surface a rigid appearance
what are the various factprs that affect skin colour
melanin
normal saturation of haemoglobin and amount of blood circulating
excessive levels of bile pigment in blood
melanin is a dark pigment dervived from where
from the amino acid tyrosine
what secretes melanin
melanocytes
where is leamin secreted into
the depp germinative layer
when melanin is secreted, what is it absorbed by
the epithelial cells
exposure to what promotes synthesis of melanin
sunlight
what does melanin protect the skin from
harmful effects of ultraviolet rays in the sunlight
what gives whin skin its pink colour
normal saturation of haemoglobin and the amount of bloof circulating in the dermis
if there are excessive levels of bile pigments in blood and carotenes in subcutaneous fat, what colour will the skin appear
yellowish colour
what are the different sensory receptors in the skin
meissners sorpuscle
Pacinian corpuscle
free nerve ending
the dermis is formed from what
connective tissue and the matric contains collagen fibres interlaces with elastic fibres
premanent striae or stretch marks is the result from what
repture of elastic fibres from overstretching of skin
what gives skin its tensile strength
collagen fibres bind water
what are the main cells found in the dermis
fibroblasts, macrophages and mast cells
what are the structures that are found in the dermis
small blood and lymph vessels
what forms a fine network with capillary branches supplying sweat glands, sebaceous glands, hair follivles and the dermis
arterioles
what are the things that the sensory factors are sensitive to
touch, temperature, pressure and pain
what is the Pacinian corpuscle sensitive to
deep pressure
what is the free nerve ending sensitive to
pain
what is the meissners corpuscle sensitive to
light pressure
what are sweat glands formed from
epithelial cells
how many types of sweat glands are there
two
what is the more common type of sweat gland
the eccrine sweat glands
when do the apocrine sweat glands become active
during puberty
where are the apocrine sweat glands ususally found
in the axilla and genital area
what is the most important function of sweat
regulation of body temperature
excessive sweating can lead to what
dehydration and serious depletion of sodium chloride
what cause the unpleasant smell of sweat glands
bacterial decomposition of the secretions of the apocrine sweat glands
what are the different types of sweat glands
the eccrine sweat glands, the apocrine sweat glands
at the base of of the hair follicle is a cluster of cells called what
called the hair papilla or bulb
how is hair colour determined
genetically determined and depends on the amount and type of melanin present
why does hair turn white
melanon production by the follicule stops
the little bundles of smooth muscle fibres attached to the hair follicles are called whaat
arrector pili
the sebaceous glands consist of what
secretory epithelial cells derived from the same tissue as the hair follicules
what is the name of the oily antimicrobial substance which the secaceous glands secrete
the sebum
what keeps the hair soft and pliable
sebum
what waterproofs the skin and acts as a bactericidial and fungicidial agent.
sebum
the nails are keratin platess that protect what
the tips of the fingers and toes
the hemispherical pale area of your cuticle is called what
lunula
what is the pigment which protects againts harmful ultraviolent rays in sunlight
melalin
what system is in place which regulates the balance between heat produced in the body and heat lost to the environment
the negative feedback system
what are the principle organs which produce the most heat
skeletal muscle contraction
the liver- very active metabolically
the digestive organs-generate heat during the chemical reactions in digestion
most heat loss in the body occurs through the what
through the skin
what are the four mechanisms of heat loss
radiation
evaporation
conduction
convection
how does radiotion generate in heat loss
when exposed parts of the body radiate heat away from the body
how does evaporation generate in heat loss
when the body is cooled as body heat converts the water in sweat to water vapour
how does conduction generate in heat loss
when clothes and other objects in direct contact with the skin take up heat
how does convection generate in heat loss
when air passing over exposed parts of the body is heated and rises, and cool air replaces it, setting up convection currents. convection also cools the body when clothes are worn
when the hypothalamus responds to decreasing temperature, it sends nerve impulses where and how do these places respond
arterioles in the dermis, which constrcit, decreasing blood flow to the skin
skeletal muscles, stimulating shivering
as heat is conserved, body temperature rises, when it turns back to normal, what is switched of
the negative feedback loop
when temperature rises how is heat loss increased
dilation of arterioles in the dermis- increasing blood flow to the skin
stimulation of the sweat glands-causing sweating
when body temperature is increased the sweat glands secrete sweat on to the skin surface. what mechanism of heat loss causing the body to cool down in this instance
evaporation
what is insensible water
loss of heat from the body by evaporation of water through the skin and expired air occurring even when the temperature is low
as body temperature rises what dilates
the arterioles
due to the arterioles dilating will more or less blood enter the capillaries
more
when the temperature is warm, in addition to increasing the amount of sweat produced, what else will the body do
increase the temperature of the skin and therefore more heat is lost by radiation, conduction and convection
if the environmental temperature is low or if heat production is decreased will the arterioles in the dermis contrstric or dilate
constrict
by the arterioles constricting due to low temperature of environment, what will this reduce
reduce blood flow to the body surface, conserving heat
fever is often the result of infection and is caused by what
caused by release of chemical from inflammatory cells and invading bacteria
fever is caused from an infection, caused by the release of chemical, what are these chemicals called
pyrogens
the pyrogens act on the hypothalamus during a fever, this releases what
releases prostaglandins
by the release of prostaglandins from the hypothalamus, what does this do
resets the hypothalamic thermostat to a higher temperature.
how does the body respond to prostaglandins resetting the hypothalamic thermosets to a higher temperature
body responds by shivering, activating heat promotion mechanisms
during a fever when the thermostat has been reset to the normal level what is activated
heat loss mechanisms
profuse sweating and profuse sweating during a fever is know as what
known as rigor
when the body core temperature is below 35 degrees Celsius, what is this defined as
hypothermia
at what temperature will the compensatory mechanisms that normally restore body temperature fail
32 degrees celcius
a lipid based substance presnt in the skin is converted to what, and what is it converted by
converted to vitamin D by sunlight
vitamin d is used with what other minerals in the formation and maintance of what
vitamin d along with calcium and phosphate in the formation and maintance of bone
sensory receptors in the dermis can be sensitive to what
touch, pressure, temperature or pain
stimulation of the sensory receptors generates impulses in sensory nerves, these are then transmitted where
to the cerebrall cortex
absorption of substance into the skin is limited, what are the substances that can be absorbed
some drugs when applied as transdermal patches
some toxic chemicals
the skin is a minor excretory organs for which substances
sodium chloride in sweat
urea
aromatic substances
why is a good blood supply an important factor when facilitating wound healing
a good blood supply will provide oxygen and nutiretns and remoce waste products
what are the local factors that faciliate wound healing
good blood supply
freedom from contamination e.g microbes
this type of healing follows minimal destrcution of tissue when the damaged edges of a wound are in close apposition, what type of healing is this
primary healing
what are the three stages of primary healing
inflammation
proliferation
maturation
in the first few hours of a cut, it will become inflamed and blood clot and what eles will fill the gap between them
blood clot and cell debris
in the first few hours of a cut, what will migrate into the blood clot
phagocites and fibroblasts migrate to the blood clot
during the inflamtion stage of primary healing, after the phagocytes have mirated to the blood clot. what do they next begin to do
the phagocytes begin to remove the clot and cell debris, stimulating fibroblast activity
during the inflammation stage of primary healing, after the fibroblasts have migrated to the blood clot, what do they then begin to do
fibroblasts secrete collagen fibres, which begin to bind the wound margins togther
during the proflieration stage in the primary wound healing. what type of cells increase across the wound
epithelial cells
during the prolieartion phase pf primary wound healing, what does the pidermis do in this phase
epidermis will meet and grow upwards until full thickness is restored
what does granulation tissue consist of
new capillary buds, phagocytes and fibroblasts.
what type of tissue in the proflieration stage of primary healing develops, invades the clot and then does what
granulation tissues develops, ivades the clot and resors blood supply to the wound
during the proliferation stage of primary healing, what do the fibroblasts secrete and what removes any bacteria
fibroblasts continue to secret collagen fibres as the clot
any bacteria is removed by phagocytosis
during the maturation phase of primary healing, the granulation tissue will be replaced by what
replaced by fibrous scar tissue
what makes the strenght of the wound increase during the maturation phase of primary healing
reaarngment of the collages fibres occurs and strenght of the wound increases
what type of tissue occurs when there is extensive tissue destruction or when the edges of a wound cannot be brought into apposition
secondary healing
what are the stages in secondary wound healing
inflammation
proliferation
maturation
during inflammation, in the secondary healing, what type of tissue separation happens
the separation of nectrotic tissue begins
during inflammation in the secondary healing, why does the separation of necrotic tissue occur
due to the action of phagocytes in the inflammatory exudate
how do the phagocytes reduce or prevent ingetion of the wound in the proflieartion stage of secondary healing
ingest bacteria after sepeartion of the necrotic tissue
sepeartioin of the nectrotic tissue is also called what
slough
microbroblastss develop what ability
limited abilty to contract
by microblasts contracting what does this therefore do to the wound
reducing the size of the wound and healing time
whe ngranulation tissue reaches the level of the dermis, what do the epithelial cells do
proliferate and grow towards the cetre
maturation occurs by what
fibrosis
what is fibrosis
scar tissue replaces granulation tissue until full thickness is restored
as what stage of secondary healing does granulation tissue develop
prolifeation stage
at what stage of secondary healing does sepeartion of slough tissue begin
inflammation stage
what is the process of fibrosis
granulation tissue forms, inflmmatory material is removed, leaving only the collagen fibres secreted by the fibroblasts
what type of tissue does adhesions consist of
fubrous tissue
what causes an infarction
bloackage of a blood vessel by a thrombus or an embolus
fibrosis of a large infarct can lead to what
varying degrees of organ dysfunction
as fibrous tissue ages what occurs
tissue shinkage
what effect can tissue shirinkage have on small tubular structures
may become narroe, obstructed and lose their elasticity
what affect can tissue shrinkage have on contractures
contractures may extend across joints
what is contractures
bands of shurunlen fibrous tissue
infection arises because of what
microbial contamination
what does ous consist of
dead phagocytes, other dead cells, cell debris, fibrin, inflammatory exudate and living and dead microbes
what are the most common pyogenuc pathogen
staphylococcus aurues and streptococcus pyogenes
small amounts of ppus form boils, what do larger collections form
Abscesses
s. aurens produce what enzyme
coagulase
what does the enzyme coagulase which is produced by s.aureuns do
converts fibrinogen to fibrin, localising the pus
s.pyogens produce what, this helps to do what
produce toxins that break down tissue, speading the infection
in skin ageing, as the basal layer becomes less active what thins
the epidermis thins
by the dermis thinning what does this mean there are fewer of
fewer elastic and collagen fibres
by there being fewer elastic and collagen fibres from the dermis thinning, what does this cause the skin to do
winkle and sag
changes to the skin can be accelerated by what
chronic and repeate exposure to string sunlight
why are older adults at greater risk in extreme tempearures
sweat galnd activity and temperture regaultion becomes less efficent and making olderr adults more prone to heat strokes and hypothermia
why does aging of the skin mean the skin is dry and susiptale to continual exposure to moister
less sebum is secreted
in older adults a production of what vitamin decreases and what does this result in
decreas in production of vitamin D, predisposing older adults to deficincy and reduction in bone strength
why are older adults more sensitive to sunlight and more prone to sunburn
melanovytes are less active
in the human papiloma virus, what proliferates and a small girwth therefore develops
the epidermis prolifeerates and a small, firm growth develops
impetigo is a highly infectios conditions commonly caused by what
staphyloccuc aureus
cellulitis is a spreading infection caused by what
anaerobic bacteria
cellulitis is caused by anaerobic bacteria, how is their spread facilitated
spread is facilitated by the formation of enzymes which break down the connective tissue that noramlly isolates an area of inflammation
fungal infections are more likley in cool, dry areas of skin. true or false
false. they are more likley to be found in warm moist areas such as skin folds
what is ringworm
duperficial skin infection
outward spreading ring of inflammation with clear patch of apparently normal skinin the centre
how is ringworm and tinea pedis spread
by direct contact
is dermatitis an example of a infective or non-infective disease
non infective
children, who may suffer from hay dever or asthma are often affected by which non-infective inflammatory condition
atopic dermatisis
conact dermatits is caused by what
direct constact with irritants e.g soap, detergent ..
what are trigger factors which worsen the condition of psoriasos
trauma, infection, sunburn and some drugs, anxiety and stress
psoriasis is characterised as what
exacerbation’s and periods of remission
psoriasis is sometimes associated with which other disease
rheumatoid arthritis
in psoriasis there is an increase in cell division of the epidermis, what does this mean for new cells
the new cell are pushed more quickly towards the surface layers and when they arrive at the surface they have not had time to mature into keratinised squames
with acne vulgaris sebaceous glands become blocked and then infected, what does this leads to
inflammation and pustule formation
acne vulgaris most frequently affects who
adolescent males
when pressure ulcers occurs, blood flow to the affected area is impaired and what develops
ischaemia
how are burns clasifed
according to their depth
when only the epidermis is involved, what type of burn would this be classified as
superficial
with a partial thickness burn, what layers of the skin are involved
epidermis and dermis
with a full thickness burn, what layers of the skin are destroyed
epidermis and dermis
why are full thickness burns usually relatively painless,
the sensory nerve endings in the dermis are destroyed
the extent of burns in adults is roughly estimated using which rule
the rule of nines
in adults with burns, hypovaolaemic shock usually develops when what percentage of the surface area is affected
15%
what are the complications of burns
dehydration and hypovolaemia shock hypothermia infection kidney failure contractures
how does dehydration and hypovolaemia occur in extensive burns
when there is excessive leakage of water and plasma proteins from the damaged skin surface
why would hypothermia develop in a sever burn
develops when excessive heat is lost is leakage from burns
why would infections occur from a sever burn
when subcutaneous tissue is exposed to the environment, microbes can readily infect the wound, which may result in sepsis
why might kidney failure occur after a burn
acture tubular necrosis occurs in sever burns when the kidney tubules are damaged by the large amounts of waste from haemolysed erythocytes, and inflamed and degenerating burn tissue
what is the most common type of skin cancer
basal cell carcinoma
basal cell carcinoma is associated with what
long-term exposure to sunlight and therefore most likely to occur in older adults
malignant melanoma usually originates in a what
in a mole
laignat melanoma is the proliferation of what
melanocytes
what are predisposing factors of malignant melanoma
fair skin and recurrant episodes of intensive exposure to sunlight
ka[osis sarcoma is a malignant tumorur that usually arises from where
from the walls of blood and lymphatic vessels
