somatosensory physiology

Question 1

What are the main types of sensation

Answer 1

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.

Question 2

where are sensory receptors located

Answer 2

throughout the body

Question 3

what are the main types of sensory receptors.

Answer 3

tactile (innocuous), nociceptive, proprioceptive, thermal.

Question 4

what receptors stimulates tactical (innocuous) sensations

Answer 4

mediated by low threshold mechanoreceptors, merkel, ruffini, messier and pacianian types.

Question 5

what stimulates proprioception

Answer 5

mediated by muscle (spindle) and joint (Golgi tendon) receptors, some inputs from cutaneous mechanoreceptors.

Question 6

what stimulates thermal sensations

Answer 6

mediated by thermo receptors localized to discrete zones that exhibit hot an cold sensitivity.

Question 7

what stimulates noiceptive sensations

Answer 7

mediated by mechanical, thermal & polymodal nociceptors.

Question 8

where are ruffini’s corpuscle located

Answer 8

deep in the dermis

Question 9

where are pacinian corpuscles located

Answer 9

encapsulated endings in the subcutaneous tissue

Question 10

where are merkel’s and meissners located

Answer 10

beneath the epidermis.

Question 11

which receptor type is commonly used in braille

Answer 11

merkel’ s recepetors

Question 12

what is the structure of meissner’s corpuscles

Answer 12

looping axonal terminals that inter-twine supporting cells

Question 13

what is the structure of merkel’s receptors

Answer 13

dome structure atop axon terminals

Question 14

what is the structure of pacinian corpuscles

Answer 14

sensory axon surrounded by fluid filled capsule

Question 15

what is the structure ruffini endings

Answer 15

nerve terminals intertwined with collagen fibrils

Question 16

what is the structure of nociceptors

Answer 16

free nerve endings that penetrate epithelial cells, no morphological specialization.

Question 17

how are the receptive fields of cutaneous sensory receptors tested

Answer 17

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.

Question 18

which receptors are slow adapting and which receptors are fast adapting

Answer 18

slow receptors- merkel and ruffini

fast receptors- meissner and pacinian corpuscle

Question 19

which areas of the body have high sensory innervation and can distinguish 2 points

Answer 19

fingertips, face

Question 20

which 2 types of receptors are involved in 2 point touch

Answer 20

merkel’s and meissner’s

Question 21

what receptor activated by the hot

Answer 21

Capsaicin activates Trpv1

Question 22

what receipts is activated by the cold

Answer 22

Menthol activates Trpm8

Question 23

what natural substance is capsaicin found in

Answer 23

chilli pepper.

Question 24

capsaicin belongs to which group of family

Answer 24

vanilloids

Question 25

what type of receptor does capsaicin work on

Answer 25

thermal receptor

heat and for hot food.

Question 26

what is the function of a muscle spindle fibre

Answer 26

Provide sensory feedback from muscle fibres on body position and movement

Question 27

what is the function of the golgi tendon organ

Answer 27

Golgi tendon organs regulate muscle tension or force of contraction and prevent muscle overload.

Question 28

what types of receptors are large in diameter and rapidly conduct afferents

Answer 28

mechanorecpetors and proprioceptors.

Question 29

what types of receptors are small in diameter and slow conducting

Answer 29

nociceptors and thermoreceptors.

Question 30

define dermatome

Answer 30

a region of the skin which is up plied by a single myotome.

Question 31

do dermatomes have definite boundaries

Answer 31

no-overlap occurs.

Question 32

what condition/ infection commonly has a dermatome specific presentation

Answer 32

herpes zoster.

Question 33

where is the primary somatosensory cortex and what is it’s function

Answer 33

post central gyrus

Areas are specialized e.g processes information from skin on texture, shape & size.

Question 34

what is the secondary somatosensory cortex and what is it’s function

Answer 34

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

Question 35

where does the secondary somatosensory cortex receive information from

Answer 35

corpus callosum

Question 36

where are the association centres and what are it’s function.

Answer 36

Localized to posterior parietal cortex

Plays role in integration of multimodal senses

Question 37

what did penfield discover

Answer 37

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.

Question 38

what did broadman discover

Answer 38

devised Brain into 47 areas, which had subserved different physiological functions.

Question 39

Damage to posterior parietal cortex produces unusual neurological disorders: which include.

Answer 39

Astereoagnosia, the inability to identify objects on basis of touch alone.

Neglect syndrome, body part or visual field is disregarded.