Sensory Receptors And CNS Pathways Flashcards
What does the viscerosensory system respond to?!
Internal environment
What does the somatosensory system respond to?!
External environment
Through which root do sensory afferents enter the spinal cord?!
Dorsal
Through which root do motor efferents leave the spinal cord?!
Ventral
What are the three classes of somatosensory receptors?!
Thermoreceptors
Nociceptors
Mechanoreceptors
What are poly modal receptors?!
Can respond to all forms of stimuli - mechanical, chemical and thermal
What does the dorsal root ganglion contain?!
Cell bodies
What are the sensory receptors in the skin?!
Pacinian corpuscle Merkels disks Free nerve endings Ruffini's corpuscle Meissner corpuscle
Which sensory receptors in the skin detect vibrations?!
Pacinian corpuscle and ruffinins corpuscle
Both are located deeper in the dermis
Which sensory receptors detect light touch?!
Merkels discs
Free never endings
Meissner corpuscle
What is pacinian corpuscle composed of?!
Single sensory neurone surrounded by fluid filled sacs forming an onion shape
What are the meissner corpuscles composed off?!
Looping axon terminals intertwined with supporting cells
What is Ruffini’s corpuscle composed of?!
Nerve terminals intertwined with collagen fibres
What are merkels discs composed of?!
Dome like structure of axon terminals and merkel cells
What do the free nerve endings penetrate?!
Epithelial cells
What is the process of sensory transduction?!
Stimulus deforms the nerve ending
Alters the membrane potentials = action potential
Travels along the axon to the CNS
Which are the faster conducting and larger diameter sensory afferents?!
Alpha groups or C fibres
Alpha groups
Where does nociceptive information synapse?!
Dorsal horn
Where does information regarding pressure synapse?!
Neurones in the dorsal column nuclei (brain stem)
Which follows the anterolateral pathway?!
Mechanoreceptor - information carries up the same side it arose from
What is the second order neurone in the mechanosensory pathway?!
Central neurone (to thalamus)
What is the primary neurone in the mechanosensory pathway?!
Primary afferents (into dorsal horn)
What is the 3rd order neurone in the mechanosensory pathway?!
Central neurone (to cortex)
Where does transduction of painful stimuli occur?!
Free nerve endings of unmyelinated C fibres and thinly myelinated Ad fibres
What do chemical nociceptors respond to?!
Histamine or other chemicals
Where are nociceptors found?!
The periphery as simple free nerve endings
Where do peripheral nerve fibres for nociceptors end?!
In the dermis (unmyelinated)
What type of neurotransmitter do pain afferents release?!
Excitatory - glutamate
What type of pathway does pain undergo?!
Contralateral
