unit 6 pt 2 Flashcards
Type A𝛽 (A-beta) fibers
Large diameter myelinated neurons (fast conductance)
Carry sensory information for cutaneous mechanical stimuli.
Type A𝛿 (A-delta) fibers:
Small myelinated neurons
Carry sensory information for cold, fast pain (nociceptors)
Type C fibers
Small diameter, unmyelinated neurons (slow conductance)
Carry sensory information for slow pain (nociceptors)
Mechanoreception (what, where, how is it stimulated)
most abundant receptor type
touch, pressure/stretch
Mostly found in skin and in some internal organs
Stimulated by different types of physical contact/deformation
-Stretch
- Steady pressure
- Fluttering/stroking movements
- Vibrations
where does Mechanoreception occur
occurs through opening of mechanically gated ion channels.
Deformation of the receptor membrane in response to the stimulus opens the ion channel
and allows
ions (usually Na+) to move into or out of the receptor cell causing a graded potential.
Thermoreception (what, contains?)
temperature
are free nerve endings in the skin,
liver, skeletal muscles, and hypothalamus
transient receptor potential (TRP) channels. These can be classified as cold receptors and warm/heat receptors
depends on trp
Thermoreception: which channels open/close when cold
open Na+ and Ca++
close K+ leakage channels, which
would also lead to a depolarizing graded potential
how are Thermoreceptors stimulated by chemicals
mint = cold
chilly= hot
signal transduction is likely to occur via GPCR second messenger pathways.
Nociception
pain/itch
Free nerve ending in the skin, muscles, joints, bones and some internal organs (viscera)
what lacks Nociception
cns
brain can perceive pain anywhere in body except itself
how is Nociception activated
Activated by strong noxious (harmful) stimuli that may damage tissue.
ex: extremely cold/hot temps, extreme pressure
Nociception: slow vs fast pain
fast:
transmits rapidly to CNS through type A𝛿 fibers
ex: stubbing toe
slow:
transmits more slowly to CNS through type C fibers
ex: pain after stubbing toe
Olfaction
Form of chemoreception
bipolar neurons in the roof of the nasal cavity.
These synapse with secondary neurons in the olfactory bulb
Olfactory in limbic system
smell can be linked to
emotions/memory
For olfaction- If the stimulus is strong enough and the
graded potential large enough
an action
potential occurs on the axon of the olfactory receptor, which will release neurotransmitter
onto the secondary sensory neuron in the olfactory bulb
Gustation form of and linked to… what does it include
chemoreception, olfaction
Taste buds are composed of up to 150 taste receptor cells TRCs.
TRCs regenerate themselves ~
every 10-14 days
Gustation: The different taste sensations use
different signal transduction pathways
Sweet, bitter, and umami use GPCR second messenger pathways that activate a G-protein
called gustducin
