Skin 3 - Physiology Flashcards
What are the 5 skin receptors?
Free nerve endings, tactile discs, tactile corpuscles, lamellar corpuscles, bulbous corpuscles
These receptors are mostly unmyelinated small diameter fibres, but some small diameter myelinated fibres that have small swellings at distal ends. It is the most common receptor in skin
Free nerve endings
These are small swellings at distal ends that have receptors that correspond to various stimuli (nociceptive, thermal, chemical)
Sensory terminals
TRPV1 receptors are an example of?
Cation channels that may be found in the sensory terminals
H1 receptors are an example of?
Chemical receptors that may be found in the sensory terminals
These are free nerve endings located in the deepest/basal layer of the epidermis. (it doesn’t extend all the way down to the dermis)
Tactile/Merkel discs
What is the hormone responsible for communication between tactile epithelial cell and nerve ending?
Serotonin
What kind of receptors are usually found abundant in finger tips (with small receptive fields?)
Tactile discs
This is a receptor sensitive to an objects physical features like fine touch and light pressure as well as texture, shape and edges
Tactile discs
This is located in papillary layer of the dermis and are spiraling, branching unmyelinated sensory terminals surrounded by modified Schwann cells and a thin oval connective tissue capsule.
Tactile corpuscles
This is a receptor commonly found in finger pads, lips, eyelids, external genitalia, soles of feet or nipples.
Tactile corpuscles
These receptors are sensitive to shape and textural changes in exploratory touch like reading Braille text; as well as low frequency vibrations.
Tactile corpuscles
These are scattered deep in the dermis and hypodermis. It is a single dendrite lying within concentric layers of collagen fibres and specialised fibroblasts.
Lamellar corpuscles
How are the layers of lamellar corpuscle separated from each other?
Through gelatinous interstitial fluid
How does lamellar corpuscle trigger an AP?
If deep and sustained pressure is applied, the capsule that surrounds the corpuscle is deformed and forms a pressure wave that goes to the middle to open pressure sensitive Na+ channels in sensory axon.
This receptor relaxes quickly and so APs are rapidly adapting.
Lamellar corpuscle
This receptor is stimulated by deep pressure and vibration.
Lamellar corpuscle
This is located in the dermis and subcutaneous tissue. It is a network of nerve endings intertwined with a core of collagen fibres that are continuous with those of surrounding dermis. A capsule surrounds the entire structure.
Bulbous corpuscle
This receptor is sensitive to sustained deep pressure and stretching or distortion of the skin.
It plays a role for signaling continuous states of ddeformation of the tissues.
Bulbous corpuscle
What kind of receptors are usually found in joint capsule?
Bulbous corpuscle
What does the bulbous corpuscle help with in the joint capsule?
Proprioception/degree of joint rotation
What does the bulbous corpuscle help with in fingers?
To modulate grip (monitor slippage of objects)
This is the reduced activation of a1 receptors on vascular smooth muscle and so increases blood flow to the skin
Vasodilation
This is the activation of a1 receptors on vascular smooth muscle to decrease blood flow to the skin
Vasoconstriction
During vasoconstriction there is?
a) increased extracellular calcium and GPCR couples to intracellular 2nd messengers
b) decrease extracellular calcium and GPCR couples to intracellular 2nd messengers
c) increased intracellular calcium and GPCR couples to intracellular 2nd messengers
d) increased intracellular calcium and GPCR couples to intracellular 2nd messengers
C) increased calcium and GPCR couples to intracellular 2nd messengers
- increased calcium means more actin-myosin interactions
This happens during heat stress and exercise. Where the body responds to an increase in core temperature with large amounts of blood flow to the skin.
Active vasodilation
What are the primary mechanisms of heat transfer?
Convection, conduction, evaporation, radiation
These are glands innervated by sympathetic cholinergic nerves. It may also be stimulated by adrenalin in response to stressful stimuli.
Eccrine sweat glands
What does it sympathetic cholinergic mean?
These specific sympathetic nerves release Ach instead of norepinephrine
This is the area of the hypothalamus that contains heat and cold sensitive neurons.
Preoptic area
What are 3 potential complications of severe burns?
Dehydration + hypovolemic shock
Infection/sepsis
Hypothermia
These are muscles innervated by a1 receptors and attach the hair follicle to the upper dermis. The contractions pulls hairs upright in response to cold stimuli.
Arrector pili muscles
What receptors are found on arrector pili muscles?
a1 receptors
What are the heat generating mechanisms?
Thermogenesis (heat generation)
- shivering - ATP turning into ADP + Pi + movement + heat
- non-shivering - increased SNS activation - increases adrenalin production in adrenal medulla - increases amount of intracellular Ca2+ - which leads to vasoconstriction of blood vessels.
- increased cellular metabolism (glycogenolysis AKA formation of energy/glucose/ATP in the liver and the muscle)
- uncoupling of Oxidative Phosphorylation to produce heat rather than ATP
- Increased Thryoxine production to increase BMR
- arrector pili muscle - traps heat in to conserve heat
