Somatosensation-Touch

Question 1

where does somatic sensation originate from?

Answer 1

the activity of afferent nerve fibres whose peripheral processes ramify within the skin

Question 2

where do cell bodies of afferent fibres reside?

Answer 2

in the dorsal root ganglia

Question 3

where do the dorsal root ganglia lie?

Answer 3

alongside the spinal cord and brain stem in the PNS

Question 4

what is sensory transduction?

Answer 4

the process of converting the energy of a stimulus into an electrical signal so our brain can understand it

Question 5

what is the AP firing rate proportional to?

Answer 5

the magnitude of the stimulus

Question 6

what are the 2 types of afferent nerves?

Answer 6

free nerve endings (pain)
encapsulated endings (non painful sensation)

Question 7

what are encapsulated endings surrounded by?

Answer 7

specialized receptor cells-> mechanoreceptors

Question 8

what are discriminative (fine touch) mechanoreceptors?

Answer 8

Meissners corpuscles
Pacinians corpuscles
Ruffini organs
Merkel disks

Question 9

what are free nerve endings for?

Answer 9

crude touch, temp, pain

Question 10

what are common properties of mechanoreceptors?

Answer 10

1:transduction (if there is an adequate stimulus -> depolarization occurs)
2:no spontaneous activity (APs only produced when adequate stimulus is present)

Question 11

what are the distinct functional properties of mechanoreceptors?

Answer 11

1: axon diameter
2:receptive field size
3:temporal dynamics of response
4:quality of somatic stimulation

Question 12

what does axon diameter determine?

Answer 12

conduction speed

Question 13

what is the receptive field size?

Answer 13

the area of skin surface over which stimulation results in a significant rate of action potentials

Question 14

what is the functional property of the receptive field size?

Answer 14

it allows your brain to determine the location of the stimulus

Question 15

does every sensory neuron have a receptive field?

Answer 15

yes. its the region of the skin that influences that neuron

Question 16

what does size of the receptive field depend on?

Answer 16

how widespread the branching of its terminals are

Question 17

what is the con of a large receptive field?

Answer 17

can’t give accurate information about where the stimulus is within this field

Question 18

what is the pro of a small receptive field?

Answer 18

more precise information about location of stimulus

Question 19

what is spatial acuity?

Answer 19

ability to distinguish different points on the skin

Question 20

what is spatial acuity dependent on?

Answer 20

innervation density (how many receptors in an area)

receptive field size of the receptor

Question 21

what is temporal dynamics of response?

Answer 21

some afferents fire rapidly; others generate sustained charge

Question 22

are Merkel disks and Ruffini organs slow or rapidly adapting?

Answer 22

slow (static)

Question 23

are meissner and pacinian corpuscles slow or rapidly adapting?

Answer 23

rapidly (dynamic)

Question 24

what is quality of somatic stimulation?

Answer 24

respond to mechanical change vs temperature change

Question 25

using the braille example, what does the merkel,meissner, pacinian, and Ruffini mechanoreceptors detect?

Answer 25

Merkel- details
meissner- coarser representation
pacinian and Ruffini- no detail but rather tracking of finger movement and position

Question 26

which direction is the post central gyrus organized?

Answer 26

medial to lateral

Question 27

what is the amount of brain devoted to a body part related to?

Answer 27

tactile acuity