Lecture 3 Flashcards
What are the 5 different types of receptors?
Free nerve endings, tactile (Merkel) discs, tactile (meissner) corpuscles, lamellar (pacinian) corpuscles, bulbous corpuscles
What are free nerve endings?
Most common receptor in skin, terminal branches extend up into layers of the epidermis, most cation channels
What are tactile (Merkel) discs?
Deepest layer of dermis, detect stimuli in tactile epithelial cells and relays it to sensory nerve terminals itself via serotonin, abundant in fingertips (small receptive field)
What are tactile (meissner) corpuscles?
Located in papillary layer of dermis, beaching unmyelinated sensory terminals surrounded by modified Schwann cells and enclosed in a thin oval fibrous connective tissue capsule, senses delicate touch
What are lamellar (pacinian) corpuscles?
Scattered deep in dermis and hypodermis, single dendrite within layers of collagen fibres and specialised fibroblasts, jelly fluid in between, deformation of capsule opens na channels in axon, rests quickly
What are bulbous corpuscles?
In dermis and subcutaneous tissue, network of nerve endings intertwined with a core of collagen fibres continuous with collagen in dermis, heavy / prolonged force on dermis transmits to bulbous corpuscles
How is skin blood flow controlled?
Sympathetic nervous system - noradrenaline binds to alpha 1 receptor in skin, GPCR coupled to produce second messenger, more calcium, more cross bridge formation, contraction, constriction
Eccrine sweat gland role in thermoregulation?
SNS - ACh released onto mAChRs produce watery salty sweat
What is radiation?
Heat loss by infrared rays
What is conduction?
Loose heat to air surrounding body (down gradient)
What is convection?
Hot air rises and replaced with cool air around body restoring gradient
What is evaporation?
Takes heat energy to cause water to evaporate which is taken from the body
What is core body temperature?
Temperature of blood around organs like heart, brain, lungs (most efficient at 36.5-37.5)
Mechanisms for heat loss?
Heat loss centre activated, decrease SNS activity for vasodilation, increase SNS cholinergic activation of mAChRs on sweat glands for more sweating, increase respiratory rate, behavioural changes
Where is core body temperature regulated?
Pre-optic area of hypothalamus containing central thermoreceptors
Mechanisms for heat generation?
Heat gain centre activated, heat transfer from arteries to veins, shivering (increased tone of muscles), non-shivering thermogenesis (glucagon beak down of brown fat into heat instead of ATP), increase thyroxine (TSH and TRH increase basal metabolic rate)
What are arrector pili muscles?
Attach to hair follicle on underside of dermis, contraction pulls hair follicle so stands upright, simple / goosebumps, compressed sebaceous glands
What is physiological feed forward in humans?
Peripheral thermoreceptors in skin telling you CBT will drop so can start taking action before this occurs
Consequences of severe second and third degree burns?
Lost water proofing layer of epidermis, loose fluid, make capillaries leaky into burn area causing loss of water
Fluid replacement for burn patients rules?
Rule of 9s
Need to know percentage of total body surface of area involved
Potential complications of severe second and third degree burns?
Skin function - dehydration and hypovolemic shock (very low blood pressure), infection/sepsis and hypothermia
