somatosensory physiology Flashcards
What are the main types of sensation
pain- inside and outside propriception- vital for movement. Temperature- inside and outside Pressure- inside and outside Vibrations-different from pressure- different from pressure dorsal column.
where are sensory receptors located
throughout the body
what are the main types of sensory receptors.
tactile (innocuous), nociceptive, proprioceptive, thermal.
what receptors stimulates tactical (innocuous) sensations
mediated by low threshold mechanoreceptors, merkel, ruffini, messier and pacianian types.
what stimulates proprioception
mediated by muscle (spindle) and joint (Golgi tendon) receptors, some inputs from cutaneous mechanoreceptors.
what stimulates thermal sensations
mediated by thermo receptors localized to discrete zones that exhibit hot an cold sensitivity.
what stimulates noiceptive sensations
mediated by mechanical, thermal & polymodal nociceptors.
where are ruffini’s corpuscle located
deep in the dermis
where are pacinian corpuscles located
encapsulated endings in the subcutaneous tissue
where are merkel’s and meissners located
beneath the epidermis.
which receptor type is commonly used in braille
merkel’ s recepetors
what is the structure of meissner’s corpuscles
looping axonal terminals that inter-twine supporting cells
what is the structure of merkel’s receptors
dome structure atop axon terminals
what is the structure of pacinian corpuscles
sensory axon surrounded by fluid filled capsule
what is the structure ruffini endings
nerve terminals intertwined with collagen fibrils
what is the structure of nociceptors
free nerve endings that penetrate epithelial cells, no morphological specialization.
how are the receptive fields of cutaneous sensory receptors tested
a) Testing the receptive field of sensory receptors using a stimulus probe on the hand, and recording action potentials from a single median nerve axon.
b) Results for main types of cutaneous sensory receptors.
which receptors are slow adapting and which receptors are fast adapting
slow receptors- merkel and ruffini
fast receptors- meissner and pacinian corpuscle
which areas of the body have high sensory innervation and can distinguish 2 points
fingertips, face
which 2 types of receptors are involved in 2 point touch
merkel’s and meissner’s
what receptor activated by the hot
Capsaicin activates Trpv1
what receipts is activated by the cold
Menthol activates Trpm8
what natural substance is capsaicin found in
chilli pepper.
capsaicin belongs to which group of family
vanilloids
what type of receptor does capsaicin work on
thermal receptor
heat and for hot food.
what is the function of a muscle spindle fibre
Provide sensory feedback from muscle fibres on body position and movement
what is the function of the golgi tendon organ
Golgi tendon organs regulate muscle tension or force of contraction and prevent muscle overload.
what types of receptors are large in diameter and rapidly conduct afferents
mechanorecpetors and proprioceptors.
what types of receptors are small in diameter and slow conducting
nociceptors and thermoreceptors.
define dermatome
a region of the skin which is up plied by a single myotome.
do dermatomes have definite boundaries
no-overlap occurs.
what condition/ infection commonly has a dermatome specific presentation
herpes zoster.
where is the primary somatosensory cortex and what is it’s function
post central gyrus
Areas are specialized e.g processes information from skin on texture, shape & size.
what is the secondary somatosensory cortex and what is it’s function
adjacent to primary somatosensory cortex.
Plays a key role in sensory and motor integration
Receives corpus callosum inputs to form ‘joined -up’ body image
Build info from multiple body areas, body image
where does the secondary somatosensory cortex receive information from
corpus callosum
where are the association centres and what are it’s function.
Localized to posterior parietal cortex
Plays role in integration of multimodal senses
what did penfield discover
each part of the body is represented on two strips of the brain’s cerebral cortex, the somatosensory cortex (“sensory homunculus” ), which receives sensations of touch, and the motor cortex (“motor homunculus”) which controls movements.
what did broadman discover
devised Brain into 47 areas, which had subserved different physiological functions.
Damage to posterior parietal cortex produces unusual neurological disorders: which include.
Astereoagnosia, the inability to identify objects on basis of touch alone.
Neglect syndrome, body part or visual field is disregarded.
