Process of Somatosensory input Flashcards
What does the somatosensory system do?
Mediates all sensation that are not visual, auditory, gustatory, olfactory or vestibular
What are exteroceptive sensations?
Sensation from the surface of the body
What are proprioceptive sensations?
Sensation from sensors in muscles, tendons and joints concerning posture and movement
What are visceral sensations?
Sensation from internal organs
What is modality?
Type of stimulus transduced into an electrical signal (i.e. pain, itch etc.)
What are deep sensations?
From fasciae, muscles and bone
What are low threshold units?
Respond to low intensity stimuli
What are high threshold units?
Respond to high intensity stimuli
What is a type of high threshold unit?
Nociceptor
What sort of stimuli induce a response from low threshold mechanoreceptors (LTM)?
Touch, vibration, pressure
What is adaption?
The ability of a receptor to display a rate of change in the firing of action potentials under stimuli
What is conduction velocity?
The speed at which a neuron is able to conduct
How does myelination effect conduction velocity?
The thicker the myelination, the faster the neuron can conduct
What is receptive field?
The region that when stimulated causes a response in a specific neuron
What do free nerve endings do?
Responsible for sensation of pain and temprature
What do Meissners corpuscles do?
Respond to stroking and flutter
What do Merkel’s discs do?
Detect pressure and texture
Where are meissner’s corpuscles found?
Often at areas where two-point discrimination is found. Very superficial
What do Ruffini endings do?
Respond to stretching of skin - (constant stimuli)
What do Pacinian corpuscles do?
Respond to vibrating stimuli - (rapidly changing stimuli)
Where are merkel cells found?
Superficially
Where are Pacinian corpuscles found?
Deep
Where are Ruffini endings found?
Deep
What are laminae of the spinal cord?
10 layers of grey matter within the spinal cord
What laminae do nociceptors terminate in?
1&2
What laminae do low threshold mechanoreceptors terminate in?
3-6
What laminae do proprioceptors terminate in?
7-9
What class of fibres transmit mechanical information
Ab
What class of fibres transmit proprioceptive information
Aa
What class of fibres transmit nociceptive information
Ac
Where do the proprioceptive and mechanical sensation pathways decussate?
Medulla
Where do the pain sensation pathways decussate?
spinal cord
Damage to one side of the spinal cord would result in loss of proprioceptive and mechanical sensation on what side?
The ipsilateral side
Damage to one side of the spinal cord would result in loss of pain sensation on what side?
The contralateral side
