Module 1: Skin Flashcards
How much percent of body is skin?
16%
Skin covers how much surface area?
1.5-2m^2
Functions of skin include
protection, excretion, thermoregulation, producing melanin and keratin, storing lipids, synthesising vitamin D and detecting aspects of touch
Layers of the skin from outermost to innermost
epidermis, dermis and hypodermis
Four layers of epidermis from outermost to innermost
stratum corneum, stratum granulosum, stratum spinosum and stratum basale
is the epidermis shed
Yes
is there circulation to the epidermis
no
the epidermis can be described as a
keratinocyte conveyor
the protein fibres in the dermis are
collagen and elastin
is the dermis shed
no
does the dermis nourish the epidermis
yes
the function of the hypodermis is
insulation
the hypodermis is made from
adipose tissue
thick skin contains an extra layer of
epidermis
thick skin is found in places
like the palms of hands and soles of feet, places with no hair
a thin dermis leads to
sagging and wrinkling
sagging and wrinkling is due to a lack of
collagen
as the skin ages there is a
slower skin repair
drier epidermis is due to
less sebum
less pigmentation results in
pale skin and grey hair
accessory structures of skin include
hair, acne, sweat glands, receptors and nails
the structure of hair is
hair shaft, hair follicle, arrector pili muscle and sebaceous gland
increased acne risk is caused by
increased sebum
function of nails
protect fingertips and enhance sensation
melanin absorbs
UV light
What is the function of melanin absorbing UV light
protects cells against UV damage
where is melanin produced
melanocytes
melanocytes are transferred to epidermal cells by
melanosomes
a mole is
a cluster of melanocytes
sun exposure can cause
over proliferation
freckles are caused by
melanocytes overproducing melanosomes
overproduction of melanosomes is caused by
sun exposure
melanocytes are only found in the
stratum basale
melanosomes are found in
epidermis
density of melanocytes varies throughout the ___ but not between ___
body; races
Vitamin D is essential for
normal calcium metabolism and strong bones
Vitamin D deficiency affects
bone strength and moods
what type of pigmented people are more susceptible to vitamin D deficiency
highly pigmented in extreme latitudes
What country has one of the highest rates of skin cancer in the world
NZ
Basal cell cacinoma originates in the
stratum basale
metastasis is rare in which skin disease
basal cell cacinoma
malignant melanoma originates in the
melanocytes
metastasis is highly common in which skin disease
malignant melanomma
Tattoo
artificial pigmentation deposited deep within the skin
tattoos are in which layer of the skin
dermal
immune cells can do what to pigment
capture it but not break it down
types of tattoo include
trauma, decorative and cosmetic
receptors of the skin are
free nerve endings, tactile discs, tactile corpuscles, lamella corpuscles and bulbous corpuscles
the most common receptor in the skin is
free nerve endings
structure of free nerve endings
mostly unmyleinated small diameter fibres but also some small diameter myelinated fibres which usually have small swellings at distal ends
the small swellings on the distal ends of free nerve endings are called
sensory terminals
function of sensory terminals
cation channels–> depolarization–> APs
free nerve endings respond to
temperature, painful stimuli, some movement/ pressure/ itch.
tactile discs are
free nerve endings located in deepest layer of epidermis
tactile discs are associated with
large disc shaped epidermal (merkel) cells
the communication between merkel cells and nerve ending is due to
serotonin (5HT)
tactile discs are abundant where
fingertips and very small receptive fields
tactile discs respond to
objects physical features ie. texture, shape and edges. fine touch and light pressure
tactile corpuscles are located
in papillary layer of dermis
tactile corpuscles are found mainly in
thick skin
are tactile corpuscles encapsulated
yes
tactile corpuscles sense
fine and discriminative touch, light pressure and low frequency vibration.
lamellar corpuscles are scattered
deep in with dermis and hypodermis
structure of lamellar corpuscles
single dendrite lying with concentric layers of collagen fibres and specialised fibroblasts
collagen layers of lamella corpuscles are separated by
gelatinous interstitial fluid
lamellar corpuscles are sensitive to
deep pressure
bulbous corpuscles are also known as
ruffinis endings
bulbous corpuscles are located in
dermis and subcutaneous tissue
structure of bulbous corpuscles
network of nerve endings intertwined with a core of collagen fibres that are continuous with those of the surrounding dermis. capsule surrounds the entire structure,
bulbous corpuscles are sensitive to
sustained deep pressure, stretching and distortion of skin
bulbous corpuscles can be commonly found in
joint capsules
a high density of bulbous corpuscles can be found
around fingertips
why is there is a high density of bulbous corpuscles around fingertips
to allow for modulation of grip
the sympathetic nervous system does what to smooth muscle to regulate temperature in skin
smooth muscle in walls of arteries and pre-capillary sphincters innervated by SNS
noradrenaline acts on ___ on this vascular smooth muscle in the skin
alpha 1 adrenergic receptor
noradrenaline acting on alpha 1 adrenergic allows
GPCRs coupled to the intercellular 2nd messengers
GPCRs coupled to the intercellular 2nd messengers allows for
an increased intracellular Ca++ and therefore constriction of skin blood vessels.
eccrine sweat glands are innervate
by the sympathetic nervous system
sympathetic chollinergic
release ACh into mAChRs (GPCRs)
some eccrine sweat glands can also be stimulate by ___ when nervous
adrenaline in blood acting on beta receptors
when body temp increases a ___ on skin blood vessels results in ___
decrease SNS activation of alpha 1; vasodilation
when body temp increase an ___ on sweat glands results in ___
increase SNS cholinergic activation of mAChRs; sweating
what area of the hypothalamus contains heat and cold sensitive neurons
preoptic area
heat and cold sensitive neurons are also known as
central thermoreceptors
heat generating mechanisms include
shivering, non-shivering thermogenesis, increase in thyoxine
method of shivering
increased tone skeletal muscle, when tone rises above critical level, shivering begins due to oscillatory contractions of agonist and antagonist muscles mediated by muscle spindles (stretch receptors)
method of non-shivering thermogeneis
increase sympathetic nerve activity and increase circulating adrenaline/noradrenaline from adrenal medulla
an example of increased cellular metabolism is
increased glycogenolysis in liver and muscle
heat production instead of ATP occurs in what fat
brown
heat production instead of ATP is the result of
uncoupling of oxidative phosphorylation
an increase in thyroxine is the result of
a response to TRH and TSH
an increase in thyroxine increases
basal metabolic rate
arrector pili muscles are
smooth muscle innervated by SNS alpha 1 receptors
arrector pili muscles attach
hair follicle to upper dermis
function of arrector pili muscle
contraction pulls hair upright and dimples skin ie. goosebumps and also compressesd sebaceous glands which lubricate skin
first degree burns are
superficial and only involve the outer layers of epidermis
first degree burns look
red, pink, dry and painful
are there blisters in first degree burns
no
how long do first degree burns take to heal
3-10 days
second degree burns involve what layers of skin
epidermis and varying amounts of dermis
second degree burns look
painful, moist, red and blistered
how long do second degree burns take to heal
1-2 weeks
third degree burns involve what tissue
full thickness ie. into the subcutaneous tissue and may involve muscle and bone.
third degree burns look
varied in colour from waxy white through to deep red or black. hard dry and leathery
are third degree burns painful
no, as these areas do not contain any working sensory nerve endings
how long do third degree burns take to heal
weeks to regenerate plus scarring
rule of 9s
helps us work out % of total body surface area involved.
in an adult TBSA of head is
9%
in an adult TBSA of upper limb is
9%
in an adult TBSA of trunk is
36%
in an adult TBSA of lower limb is
18%
in an adult TBSA of genitalia is
1%
in an child TBSA of head is
15%
in an child TBSA of trunk is
32%
in an child TBSA of upper limb is
9%
in an child TBSA of lower limb is
17%
in an child TBSA of genitalia is
1%
