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What are the 7 functions of the skin?
protect underlying tissues and organs against impact, abrasion, fluid loss and chemical attack
excrete salts, water and organic wastes
maintain normal body temp
produce melanin and keratin
synthesis vitamin D3
store lipids in adipocytes in the dermis
detect touch, pressure, pain and temp and relay the info to the nervous system
what does melanin do?
protects underlying tissue from ultraviolet radiation
what does keratin do?
protects against abrasion and serves as water repellent
what are the 3 layers of the skin? and describe each layer?
Epidermis
barrier
mostly keratinocytes
no blood circulation
dermis
protein fibres for strength
vascular
hypodermis
adipose tissue
What layer of the skin is the subcutaneous layer?
hypodermis
what tissue type is epidermis made of?
epithelial tissue
what two layers is the dermis made of and describe them?
papillary layer - consists of highly vasularised tissues (for nourishment)
reticular layer - mesh like structure made of collagen and elastin fibres (for strenght)
What are the 2 plexuses of the dermis? describe them
cutaneous pelxus
network of bood vessels
supplies hypodermis, deeper dermis, capillaries for hair follicles and sweat glands
subpapillary plexus
branches from cutaneous plexus
lies deep to the papillary layer of dermis '
network of blood vessels for upper dermis and epidermis
What is they hypodermis made of and what is its function?
adipocytes
stores energy and provides insulation.
Where is hair found and what is it made of?
all over the body except palms, soles and lips
made of dead keratinized cells
What three things does a hair follicle consist of? describe them
Arrector pilli muscle - contraction that produces goose bumps to improve insulation
root hair plexus - collection of sensory nerves at the base of each hair follicle
Sebaceous glands - produce sebum, naturally moisturises skin and water repellent
what are the two types of sweat glands in the skin? where are they found? what are they important for?
eccrine - most areas of the skin - thermoregulation and excretion
apocrine - armpit, groin, nipple - influenced by hormones
what is the 3 functions of nails?
protect fingers / toes
enhance sensation
sensory receptors require deformation
what are the signs of aging skin?
thin dermis and epidermis (reduced collagen)
slower skin repair
drier epidermis
imparied cooling
less pigmentation
describe the effect tobacco has on skin aging?
damages collage and elastin
describe the effect vaping has on skin aging?
nicotine reduces blood ciruclation in the dermis
where is melanin produced? and where are they found?
melanocytes
in the stratum basale
how are melanocytes transferred to epidermal cells? and where are they found?
by melanososmes - throughout the epidermis
what is the difference between a mole and a freckle?
mole - cluster of melanocytes - caused by sun exposure
freckle - melanocytes overprocuding melanososmes
What is vitamin D good for? what does vitamin d deficiency cause?
essential for calcium metabolism and strong bones
effects mood
UV exposure in the skin is required for the synthesis of vitamin d
rickets
What are the two types of skin cancer and describe them
basal cell carcinoma
common
originates in stratum basale
metatstasis (spread) is rare
malignant melanoma
rare but deadly if not treated
originated in melanocytes
highly metastatic
what layer does a tattoo get inserted into? Why is there so much pain during a tattoo?
dermal layer
dermal layer contains free nerve endings and pain receptors
Describe the process of reducing skin blood flow
Noradrenaline acts on a1 adrenergic receptors on this vascular smooth muscle in the skin
GPCRs coupled to intracellualr 2nd messengers = increased intracellualr ca2+ = constriction = reduced skin bloodflow
describe the process of increasing skin blood flow
reducing SNS activation of a1 receptors therefore causes relaxation of arteries to skin —> increases blood flow
Activation of A1 receptors = ?
Reduced activation of A1 receptors = ?
Vasoconstriction
Vasodilation
what are the 4 primary mechanisms of heat transfer?
radiation
evaporation
convection
conduction
describe the structure and function of eccrine glands
innervated by the SNS
they release Ach
causes sweat when we are hot
what does the preoptic area of the hypothalamus contain?
heat and cold sensitive neurons
describe vasodilation
decrease SNS activation of a1 on skin blood vessels
describe sweating
increase SNS cholinergic activation of mAChRs on sweat glands
what receptors detect temperature below set point?
central thermoreceptors
what are 3 examples of heat generating mechanisms? and describe them
shivering - contractions of agonist and antagonist muscle
non shivering thermogenesis - circulating adrenaline
increased thyroxine - in response to TSH and TRH
How do goosebumps work?
Arrector pilli muscles contracts and pulls the hairs upright. Creates a air bubble and seals the heat so you don’t lose any.
if you have bruns what is a resut of this?
capillaries may leak
What complications can severe bruns lead to?
dehydration
hypothermia
infection / sepsis
renal failure