NEUR531 - Somatosensory Sensations Flashcards
Describe the different types of mechanoreceptors and the
type of touch information each is tuned to detect.
LEARN THESE
Describe the receptive fields and adaptation rates of the
different mechanoreceptors.
Describe the different mechanical forces that lead to
changes in ionic current in mechanosensitive ion channels.
Give a detailed account of the process by which peripheral
chemical mediators lead to sensitisation of nociceptors
Describe the difference between fast (first) and slow (secondary) pain.
Explain how thermoreceptors adapt in response to hot
and cold stimuli
Describe the mechanism of how lateral inhibition of the
somatic sensory system leads to contrast enhancement
What is somatic sensation?
- Enables the body to feel, ache, sense pressure and temperature
- TOuch and pain
What receptors are touch associated with?
mechanoreceptors
What are the predominant receptors within the somatosensory system?
Mechanoreceptors
What’s the pacinian corpuscle associated with?
- Dermal layer
- Pressure
What do ruffinis ending associate with?
Stretch of the skin
what are Meissner’s corpuscles associated with?
- Finger tips
- Fine touch receptors
What are * Merkel’s disks associated with?
- Small receptor field
- Highly sensitive
- Lips/fingertips
- Superficial
Adaptation of pacinian corpuscles
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Do mechanoreceptors have unmyelinated or myelinated axon terminals?
unmyelinated
What primary AFFERENT FIBERS/AXONS mediate pain, temperature and itch?
C axons
Free nerve endings
What primary afferent axons mediate TOUCH sensations?
A beta
Fastest
Myelinated
Learn the primary afferent axons
wwat are 3 types of receptors that can cause pain?
- Chemical
- Thermal
- Mechanical
wwat are 3 types of receptors that can cause pain?
- Chemical
- Thermal
- Mechanical
Is fast/first pain myelinated or unmyelinated?
Myelinated
What fibers does first pain use?
A delta
Is second pain using myelinated or unmyelinated fibers?
Unmyelinated
what fibers do second pain use?
C fibers
LEARN THIS FOR EXAM
What pain sensation are associated with fast nociceptor pathway?
- Sharp
- Pricking pain
- Mechanical and thermal nociceptors
What fibres does fast pain travel ?
A delta fibers
Where do the fast pain A delta fibers travel to in the spinal cord?
SUPERFICIAL dorsal horn
What does fast nociceptor pain produce in the brain?
Well-localised painful stimuli
What neurotransmitter does fast pain use for transmission?
Glutamate
What types of sensation does the slow nocipceptor pathway produce?
Dull
Burning
Aching
What fibers does the slow nociceptor of pain travel?
C fibers
Where does the SLOW nociceptor pathway travel to the spinal cord?
DEEPER dorsal horn
What type of pain does SLOW pathway produce in the brain?
- Poorly localised
- Distressing
Where in the BRAIN does SLOW nociceptor pathway go?
- Reticular formation
- Increased alertness/arousal
Where in the brain does FAST nociceptor pathway go?
- Somatosensory cortex
- Highly localised sensations
PAIN AFFERENT REGULATION FALLS UNDER WHAT THEORY?
- Melzack and wall theory
- When you first hurt yourself
- Gate control theory
Pain regulation pathway
What is the endogenous neurotransmitter to inhibit pain?
Enkephalins
What interneurons does the higher brain activate to modulate pain?
Enkephalin-containing interneurons
What neurons STIMULATE enkephalin-containing interneurons?
5-HT sertonergic neurons
What is the most pain inducing thermoreceptor?
TRPV2
Hot receptor
DRAW THESE PATHWAYS OUT
- Variations in spinal cord injuries
Review the somatosensory areas of the cortex
The somatosensory system is at least how many senses?
4
