Somatic Sensory System

Question 1

What sensory receptors have encapsulated nerve endings?

Answer 1

meissner and pacinian corpuscles

Question 2

Where are meissner corpuscles found

Answer 2

palms, eyes, lips

Question 3

What do Meissner corpuscles detect

Answer 3

light touch, texture, movement

Question 4

Describe Meissner corpuscles

Answer 4

sensitive and rapidly adapting

Question 5

Where are Pacinian corpuscles located

Answer 5

deeper in the skin

Question 6

What do pacinian corpuscles detect

Answer 6

deep pressure, stretch

Question 7

Describe Pacinian corpuscles

Answer 7

sensitive, rapidly adapting

Question 8

Which sensory receptors have un-encapsulated nerve endings

Answer 8

Merkel discs, free nerve endings, Ruffini corpuscles

Question 9

Where are ruffini corpuscles located

Answer 9

dermis, subcutaneous tissue

Question 10

What do Ruffini corpuscles detect

Answer 10

heavy touch, pressure

Question 11

Describe Ruffini corpuscles

Answer 11

slow adapting, proprioreceptor

Question 12

Where are Merkel discs located

Answer 12

skin

Question 13

What do Merkel discs detect

Answer 13

light touch, texture

Question 14

Describe Merkel discs

Answer 14

slowly adapting

Question 15

Where are free nerve ending located

Answer 15

epithelia, connective tissues

Question 16

What do free nerve endings detect

Answer 16

pain, heat and cold

Question 17

Describe hair follicles

Answer 17

varied sensory receptors - rapid and slow

Question 18

Where are hair follicles located

Answer 18

epithelia

Question 19

What type of receptors are sensory receptors

Answer 19

CELLULAR

Question 20

How do rapidly adapting receptors respond

Answer 20

fire immediately - rapidly stop

Question 21

What do rapidly adapting receptors give information about

Answer 21

changes in the stimulus

Question 22

What do slowly adapting receptors give information about

Answer 22

persistence of stimulus

Question 23

How do slowly adapting receptors respond

Answer 23

fire slowly - continue to fire if stimulus present

Question 24

How are primary afferent axon subtypes classified

Answer 24

conduction velocity

Question 25

Where is sensory information organised

Answer 25

spinal cord dorsal horn

Question 26

Function of medial lemniscal tracts

Answer 26

carries mechanoreceptive, proprioceptive signals to the thalamus

Question 27

function of spinothalamic tract

Answer 27

carries pain, temperature signals to thalamus

Question 28

What are the two main somatosensory routes

Answer 28

medial lemniscal tracts, spinothalamic tract

Question 29

How many neurons does sensory information travel through

Answer 29

3

Question 30

Function of first order neurons

Answer 30

detect stimulus, transmit it to spinal cord

Question 31

Function of second order neurons

Answer 31

relay signal to the thalamus, gateway to the cortex

Question 32

Which order neurons are commissural?

Answer 32

second order

Question 33

Function of third order neurons

Answer 33

relay from thalamus to cortex

Question 34

How are axons of the medial lemniscal pathway organised?

Answer 34

Topologically

Question 35

Describe the pathways of first order neurons from the upper and lower body in the Medial Lemniscal system

Answer 35

upper body - lateral | lower body - medial

Question 36

What do first order axons from the lower body in the MSL synapse onto

Answer 36

neurons in gracile nucleus

Question 37

What do first order neurons from upper body in MLS synapse onto

Answer 37

neurons in cuneate nucleus

Question 38

What happens to second order neurons in the MLS

Answer 38

cross the midline

Question 39

What do second order neurons in the MLS ascend in to

Answer 39

medial lemniscus

Question 40

What is the lower body pathway

Answer 40

medial

Question 41

What is the upper body pathway

Answer 41

lateral

Question 42

What is a dermatome

Answer 42

specific domain of the body

Question 43

What are somites

Answer 43

iterated structures

Question 44

What do somites give rise to

Answer 44

musculature and skeleton

Question 45

What do sensory ganglions associate with in the embryo

Answer 45

specific somite

Question 46

What is the area of the cortex dedicated to each area of the body proportional to

Answer 46

density of innervation in that area

Question 47

Describe the cortical map

Answer 47

highly plastic - change overtime depending on usage