Sensory Systems : Touch + Pain

Question 1

Receptors

Answer 1

Allows us to perceive range of different touch and pain sensations

Question 2

Sensory pathways - pathway 1

Answer 2

• carries info of touch and position of body
• axons a send and cross to other side of brain
• most neurones project to primary somatosensory cortex

Question 3

Sensory pathways - pathway 2

Answer 3

• carries info of pain and temperature
• most neurons cross over to contralateral slide when they enter spinal cord, part of pathway continues to thalamus, other part terminates in brain stem

Question 4

Cortical Areas - S1

Answer 4

• somatopic organised according to map of body surface
• input mainly from contralateral side of body
• S1 sends output to secondary somatosensory areas + associated cortex

Question 5

SII (secondary somatosensory cortex)

Answer 5

• input from contralateral S1
• output to association cortex

Question 6

Association cortex

Answer 6

• posterior partial lobe
• input from SI and SII
• damage to right posterior lobe= asomatognosia (failure to recognise part of ones own body)

Question 7

Axons carrying pain release what 2 neurotransmitters at ther synapse ?

Answer 7

Mild pain= glutamate
String pain= glutamate + substance P

Question 8

The 2 pathways for pain, to the brain

Answer 8

1. Thalamus- somatosensory cortex pathway (sensory aspects of pain)
2. Limbic system-prefrontal cortex pathway (reacts to emotional quality associated with pain) (activity of this can be reduced in pain relief, placebos)

Question 9

What happens in pain relief (morphine)

Answer 9

• opiates bring to opiate receptors in CNS
• opiate receptors block release of substance P —> alleviates pain
• endorphins inhibit release of substance p in spinal cord from neurons that carry pain message

Question 10

Endorphines

Answer 10

• endorphins released by pleasant + unpleasant stimuli —> pain, sex, thrilling music
• endorphins release decreased if someone depressed
• explains why some injury hurts worse some times than others