Lecture 1: Cutaneous Sensation - Receptors And Primary Afferents Flashcards
What organ does cutaneous sensation refer to?
Skin.
Do Afferents sensory neurons enter the spinal cord via the dorsal or ventral root?
Dorsal root.
Which group of cutaneous receptors respond to distortion (touch and hair movement)?
Low threshold mechanoreceptors.
Which group of cutaneous receptors respond to non-damaging temperatures?
Thermoreceptors.
Which group of cutaneous receptors respond to stimuli that cause pain and potential tissue damage?
Nociceptors.
Which group of cutaneous receptors respond to itch-inducting stimuli?
Itch receptors.
Which group of cutaneous receptors may be a subset of nociceptors?
Itch receptors. Because they also respond to painful stimuli.
What are the specialised endings of low threshold mechanoreceptors?
Merkel’s disks
Ruffini endings
Meissner’s corpuscles
Pacinian corpuscles
Apart from specialised endings, there is another type of low threshold mechanoreceptor, what is it?
Hair follicle afferents.
Nociceptors, thermoreceptors and itch receptors all have what in common?
They all terminate as free nerve endings in the skin.
Which specialised ending of low threshold mechanoreceptors are fast with a small receptive field size?
Meissner’s corpuscles
Which specialised ending of low threshold mechanoreceptors are fast and have a large receptive field size?
Pacinian corpuscles.
Which specialised ending of low threshold mechanoreceptors are slow and have a small receptive field size?
Merkel’s disks.
Which specialised ending of low threshold mechanoreceptors are slow and have a large receptive field size?
Ruffini’s endings.
Do slowly adapting receptors detect displacement or movement?
Displacement. Rapidly adapting receptors detect movement.
Which specialised ending has “onion skin” of connective tissue surrounding the terminal part of the axon? And what property does it aid?
Pacinian corpuscle. It gives the receptor it’s rapidly adapting property.
What range of temperatures do thermoreceptors detect?
10 degrees C to 45 degrees C. Outside this range it gets painful and nociceptors are responsible for detection.
What are polymodal nociceptors?
Nociceptors that respond to different types of stimuli (mechanical thermal and chemical).
What are “silent nociceptors”?
Nociceptors that only respond when sensitised (e.g. after tissue injury).
Piezo2 is an example of what? Is it a small or large protein?
Mechanosensitive ion channel. It is a very large protein with >30 transmembrane domains.
Which channels are used in thermal transduction? Give an example.
Transient receptor potential channels that signal various temperatures. Eg. TRPV1 which responds to temps of >43 degrees C.
TRPM channels or TRPV channels are associated with hot or cold temperatures?
TRPM - cold
TRPV - hot
Where do primary afferents have their cell body?
In the dorsal root ganglion.
What are the two types of primary afferents?
Myelinated (A fibres - can be A beta or A delta) and Unmyelinated (C fibres).
