A & P - Sensory Nervous System

Question 1

which receptor is responsible for awareness of limb position?

Answer 1

proprioceptors

Question 2

what are chemoreceptors responsible for?

Answer 2

detection of chemicals

Question 3

which receptor detects physical distortion?

Answer 3

mechanoreceptors

Question 4

describe the steps in the somatosensory pathway I

Answer 4

1. Activation of sensory receptors
2. Transmission of sensory input to spinal cord or brainstem(1st order neuron)
3. transmission of signal via ascending pathways through thalamus (2nd order) to primary cortex (3rd order)
4. conscious perception

Question 5

when sensory signals reach the primary cortex what is the signal checked for?

Answer 5

defection
size
modality (type of specific sense. eg. touch, pain, vision)
frequency
quality
pattern

Question 6

what are sensory receptors?

Answer 6

pseudo-unipolar cells

Question 7

what is the name for a sensory receptor who’s endings are not in the connective tissue?

Answer 7

un-encapsulated - free nerve ending (eg. special senses)

Question 8

where are the nerve endings of encapsulated sensory receptor found?

Answer 8

wrapped in glia or connective tissue

Question 9

what is increased in encapsulated sensory receptors?

Answer 9

sensitivity

selectivity in respect to modality

Question 10

how many pairs of spinal nerves are there? list the segments

Answer 10

31 pairs

8 cervical
12 thoracic
5 lumbar
5 sacral
1 coxygeal

Question 11

spinal nerves carry impulses via sensory or motor axons?

Answer 11

both - they are mixed

Question 12

what does white matter in the spinal cord consist of?

Answer 12

mostly myelinated and unmylinated axons in ascending and descending tracts

Question 13

what does grey matter in the spinal cord consist of?

Answer 13

mostly cell bodies of motor neurones and neuroglia

Question 14

what information do the descending tracts of the spinal cord carry?

Answer 14

motor commands

Question 15

what information do the ascending tracts of the spinal cord carry?

Answer 15

sensory input

Question 16

what sensory information does the dorsal white column carry?

Answer 16

fine touch

properioception

Question 17

what sensory information does the spinothalamic tract carry?

Answer 17

anterior- crude touch & pressure

posterior - temperature & pain

Question 18

what sensory fibres does the dorsal column pathway use?

Answer 18

large diameter myelinated

Question 19

describe the dorsal column pathway

Answer 19

bilateral
generates contralateral signals
fast

Question 20

describe the locations of the dendrites, cell bodies and axons of the 1st, 2nd and 3rd order neurones in the dorsal column pathway

Answer 20

1st order
dendrites - periphery, cell body - DRG, axon - terminals in brain stem
2nd order
dendrite & cell body - brainstem, axon - decussates, projects into thalamus
3rd order
dendrites & cell body - thalamus
axon - projects into sensory cortex

Question 21

what sensory fibres does the spinothalamic pathway use?

Answer 21

small unmyelinated axons

Question 22

describe the spinothalamic pathway

Answer 22

bilateral
contralateral signals
slow

Question 23

what is caused by a disturbance in the spinothalamic pathway?

Answer 23

phantom limb pain

referred pain

Question 24

describe the locations of the dendrites, cell bodies and axons of the 1st, 2nd and 3rd order neurones in the spinothalamic pathway

Answer 24

1st order
dendrites - periphery, cell body - DRG, axon - terminates in spinal cord
2nd order
dendrites & cell body - spinal cord
axon - decussates, projects into thalamus
3rd order
dendrites & cell body - thalamus, axon - projects into sensory cortex

Question 25

how would pain in the head travel to the cerebral cortex via the pain signalling pathway?

Answer 25

from cranial nerves - CNV, VII, IX, X brainstem (1st order) thalamus (2nd order) cerebral cortex (3rd order)

Question 26

in the pain signalling pathway which tracts carry which information?

Answer 26

spinothalamic tract - most somatic pain signals to cortex - perception spinorecticular tract - visceral, emotional, behavioural posterior column - visceral pain

Question 27

which nerves make up the sciatic nerve?

Answer 27

L4 - S3

Question 28

where is the primary motor cortex located?

Answer 28

parietal lobe in post central gyrus

Question 29

what are nociceptors activated by?

Answer 29

chemical release from injured tissue

Question 30

when tissue is injured what chemicals are released?

Answer 30

``` bradikins prostaglandins histamine ATP K+ ```

Question 31

what is 1st pain?

Answer 31

myelinated axon fast conduction sharp, localised, stabbing pain

Question 32

what is 2nd pain?

Answer 32

unmyelinated axons slow conduction speed long lasting dull pain

Question 33

what are dermatones?

Answer 33

areas of skin innervated by sensory branch of single nerve

Question 34

how can dermatones be used as a diagnostic tool?

Answer 34

to pin point pain associated with spinal nerves

Question 35

what role does pain play in homeostasis?

Answer 35

protects and preserves body

Question 36

what is referred pain?

Answer 36

pain perceived at predictable site away from actual injury

Question 37

what is chronic pain?

Answer 37

no disease or injury no biological purpose psychological

Question 38

what is acute pain?

Answer 38

provoked by disease or injury biological purpose to protect SNS activation

Question 39

what would cause a lack of pain perception?

Answer 39

genetic diabetes drugs

Question 40

why do we feel referred pain?

Answer 40

skin and visceral nociceptive neurons on 1 interneuron brain can't distinguish source of pain pain felt at surface of skin