Somatosensory systems Flashcards
What are the somatosensory systems?
touch, proprioception, pain ,itch, visceral
What are the 2 classes of somatic sensory neurons?
dorsal root ganglion and trigeminal
What is the order of neuron fibre speed from slowest to fastest?
c < Ad < Ab
What are the properties of a stimulus?
modality
intensity
duration
location
What are slowly adapting receptors?
- fire for duration of stimulus
- larger stimulus = increased frequency
What are rapidly adapting receptors?
only fire when there is a change in intensity of a stimulus
What is the receptive field?
the spatial domain where a stimulus will excite/inhibit a neuron
What is the two-point threshold?
the ability to distinguish two stimuli as separate
What are the 4 types of mechanoreceptors?
- meissner corpuscle (superficial, small field, rapid adapting)
- Merkel cells (superficial, small field, slow)
- pacinian corpuscle (deep, large field, fast)
- ruffini endings (deep, large field, slow)
What do proprioceptors do?
report on limb position
What do joint proprioceptors do?
transduce tension in the joint capsule
What are the 2 types of muscle receptors?
muscle spindles and golgi tendons
What are the features of muscle spindles?
in parallel with fibres
sense change in length
What are the features of golgi tendon bodies?
in series with fibres
sense tension changes
What type of fibres are cold fibres?
A delta
What type of fibres are hot fibres?
C fibres
Why can high temperatures feel cold?
the cold receptors can become activated
What receptors sense dangerous temperatures?
nocieptors
What are the 4 main modalities of nocieptors?
thermal, mechanical, polymodal, silent (in inflammation)
How is diversity of nocieptors determined?
expression of transduction molecules
Is the dorsal column/ medial lemnisal system contralateral or ipsilateral?
ipsilateral
What does the ascending dorsal column convey?
mechanosensory info from limbs and trunk
is the anterolateral tract contralateral or ipsilateral?
ipsilateral (crosses midline in spinal cord)
What does the ascending anterolateral tract convey?
itch, temperature, visceral ifno
What are the 3 main divisions of the somatosemsory cortex?
primary cortex
secondary cortex
posterior parietal cortex
What are the Broadmann’s areas?
subdivisions of the primary somatosensory cortex
- 1,2, 3a and 3b
Which broadmann area gets the majority of input?
3b
