5.0 Somatic Sensation Flashcards
What skin layers are mechanoreceptors found?
Epidermis + Dermis
Slowly adapting vs rapidly adapting receptors?
Rapidly adapting receptors respond only to onset of stimulus<br></br><br></br>Slowly adapting fibres respond to steady stimulus
Define accessory structure:
A structural component that is not involved in transduction directly however plays a role in other aspects such as protection, sensitivity, conduction etc
What are the four different mechanoreceptors?
1) Merkel cell (Slow adapting type I)<br></br>2) Ruffini endings (Slow adapting type II)<br></br>3) Meissner’s corpuscles (Rapid adapting type I)<br></br>4) Pacinian corpuscules (Rapid adapting type II)
What is tactile acuity?
Being able to differentiate 2 points (hands + feet > back)<br></br><br></br>Areas with high tactile acuity have small receptive fields
Define two-point limen:
Smallest discriminable distance between two points of contact (different in different areas smaller in more mobile parts of body - e.g. hands)
What thermoreceptors respond to warm?
1) TRPV1<br></br><br></br>2) TRPV2
What thermoreceptors respond to cold?
1) TRPM8<br></br><br></br>2) Anktm1
What does the TRPV1 receptor respond to?
1) Capsaicin (in chillis)<br></br>2) Painfully hot temp (>45 degrees)
What does the TRPM8 receptor respond to?
1) Menthol<br></br>2) Non-painful temp <25 degrees
What receptor responds to Horseradish (Isothiocyanates)?
TRPA1
Define labelled line coding:
Activity in a particular fibre will always be experienced as the modality it encodes irrespective of actual stimulus.<br></br><br></br>E.g. Activity in cold fibre will always be experienced as cold (even if activity is due to hot stimulus)
What are the nociceptive fibres?
<b>1) Aδ fibre</b><br></br>Thinly myelinated<br></br>‘First’ pain<br></br><br></br><b>2) C fibre</b><br></br>Unmyelinated<br></br>‘Second’ pain<br></br>Polymodal (respond to temp, mechanical and chemical)
Arrange axons in order of their diameter:
Aα > Aβ > Aδ > C
What fibres are most affected by anoxia?
Aβ
What fibres are most affected by anaesthetic?
C + Aδ