Skin lecture 3 Flashcards
free nerve endings respond to?
Temperatrue painful stimuli movement and pressure itch (histamine response) light touch
Most common receptor in the skin?
Free nerve endings
Free nerve endings make ups?
Unmyelinated and some myelinated small diameter fibres
where are tactile (Merkel) discs?
Free nerve endings in the deepest layer of the epidermis
What do tactile (merkile) discs ?
texture, shape and edges
fine touch and light pressure
Tactile (merkel) discs are good for?
good for two point discrimination due abundance in fingertips and very small receptive fields
Where are tactile (Meissner) corpuscles located?
Papillary layer of dermis. particularly in hairless skin
Tactile (Meissner) corpuscles are good for?
delicate or discriminative touch (ie. braille text)
light pressure
low frequency vibration
Tactile (Meissner) corpuscles makeup?
Spiralling unmyelinateud sensory terminals surrounded by modified Schwann cells and encapsulated by a thin oval fibrous connective tissue capsule
Lamellar (pacinian) corpuscles are found?
scattered deep in dermis and hypodermis
Lamellar (pacinian) corpuscles are best at sensing?
deep pressure (only when first applied)
also vibration
*rapidly adapting
Lamellar (pacinian) corpuscles make up?
single dendrite lying within concentric layers of collagen fibres and specialised fibroblasts. the layers are separated by interstitial fluid
Bulbous corpuscles are located?
Dermis and subcutaneous tissue. Also found in joint capsules and high density around fingernails to monitor slippage of objects
what are bulbous corpuscles?
network of nerve endings intertwined with a core of collage fibres that are continuous with those of the surrounding dermis. surrounded by capsules
what are bulbous corpuscles sensitive to?
sustained deep pressure and stretching or distortion of the skin
Smooth muscle in walls of arteries and pre-capillary of sphincters are innervated by?
sympathetic nervous system
Noradrenaline acts on? To cause?
alpha1 adrenergic receptors on vascular smooth muscle in skin in order to reduce skin blood flow. Reducing SNS activity increases skin blood flow.
Primary mechanisms of heat transfer?
Radiation
Evaportation
convection
conduction
Eccrine sweat glands are innervated by?
sympathetic nervous system
The SNS releases what onto mAChRs (eccrine sweat glands)?
ACh, acetyl choline
Eccrine sweat glands also stimulated by?
Adrenaline in blood acting on Beta receptors
What area of the hypothalamus contains heat and cold sensitive neurons?
Preoptic area
Heat loss mechanisms?
Vasodilation of blood vessels
Sweating
Increased respiratory rate
behavioural changes
Heat generating mechanisms?
Shivering
Increased cellular metabolism like increased glyconeogenesis in liver and muscle
Thyroxine
What do arrestor pili muscles attach?
Hair follicle to upper dermis
What type of muscle is arrestor pili muscles?
smooth muscle
What do arrector pili do?
Contraction pulls hair upright and dimples skin which causes goosebumps. Also compresses sebaceous glands
How long do first degree burns take to heal?
3-10 days
What layer of skin do first degree burns affect?
Superficial so only involves outer Laye of the epidermis.
Symptoms of first degree burns?
Red/pink, dry, painful
no blisters, similar to a mild sunburn
How long does a 2nd degree burn take to heal?
approx 1-2 weeks
deeper burns can take up to a month
What layers of skin do 2nd degree burns affect?
Epidermis plus varying amounts of the dermis
Symptoms of 2nd degree burns?
Painful, moist, red and blistered, will require good dressings
What layers of the skin do 3rd degree burns affect?
Full thickness, they extend into subcutaneous tissue and may involve muscle or bone
Do people with 3rd degree burns feel pain?
No, the sensory nerve endings are destroyed.
How long do 3rd degree burns take to heal?
Weeks to regenerate plus a lot of scarring
