Somatosensory

Question 1

Somatosensory system

Answer 1

-Used by the brain to understand the bodys sensations and movements

Question 2

Somatosensory senses

Answer 2

• Discriminitive touch
• Deep touch
• Itch and tickle
• Pain
• Cold and warmth
• Position and movement

Question 3

Cutaneous senses

Answer 3

-External (exogenous) touch, pain, temperature

Question 4

Organic senses

Answer 4

-Internal (endogenous) stimuli from internal organs etc.

Question 5

Cutaneous receptors

Answer 5

-Nerve endings (afferent neurones)

Question 6

Movement of sensory information

Answer 6

-Information from the PNS is sent to the CNS via the spinal nerves in the body then the cranial nerves in the head to be processed in the somatosensory cortex

Question 7

Detecting tactile stimuli

Answer 7

• Large amounts of pressure or vibration causes dendrites to signal reeptors to open ion channels allowing an action potential to be fired along the axon to the dorsal root or cranial nerve ganglia

Question 8

Pathways from receptors to the left hemisphere

Answer 8

• Dorsal column L - precise movement and fine touch
• Spinothalamic R - pain/temperature
• to medulla to midbrain to somatosensory

Question 9

Somatosensory representation changes with practice

Answer 9

-Violinist: Right somatosensory cortex (SSC) for four fingers of left hand enlarged

Question 10

Tactile agnosie

Answer 10

-Damage to somatosensory association cortex causes inability to recognise objects by touch (E.C. though pinecone was bruch etc.)

Question 11

Pain receptors (Noiceptors)

Answer 11

• Free nerve ending receptors (pain sensitisation)
• High threshold receptors (intense pressures)
• TRPV1 receptors (extreme heat, acid and capsaicin)
• Receptors sensitive to inflammation from chemicals

Question 12

Pain axons

Answer 12

• Little - no myelin transmits dull pain relatively slow (0.5-30m/s) vs motor response (35-120m/s)
• Thinly myelinated axon conveys sharp pain quickly

Question 13

Pain neurotrsnsmitters

Answer 13

• Released into spinal cord
• Glutamate: mild pain
• Substance P and glutamate: stronger pain

Question 14

Lack of substacnce P in mice

Answer 14

-React to severe injury as if it was a mild injury

Question 15

Emotional pain fMRI

Answer 15

-FMRi found that activity is seen in the somatosensory cortex when participant is given an electric shock. When a loved one receives, and electric shock activity is seen in the cingulate cortex (Empathy)

Question 16

Emotional pain hypnosis

Answer 16

-Half of participants were hypnotized; those hypnotizes were told they would put their hand in an ice bucket, and they wouldn’t feel anything. The hypnotized group showed less intensity in the cingulate cortex than the non-hypnotized group.

Question 17

Emotional pain as a basic need

Answer 17

-Infants feel emotional pain when separated from their caregiver, and caregivers experience emotional pain to drive them to care for infants, suggesting this pain is evolutionary necessary and the first basic need.

Question 18

Relieving emotional pain

Answer 18

-Paracetamol and Tylenol can relieve physical and emotional pain

Question 19

Dangers of insensitivity to pain

Answer 19

-People with a gene that inactivates pain axons suffer repeated injuries

Question 20

Endogenous vs exogenous

Answer 20

• Naturally occurring

- From outside the body

Question 21

Opiods and endorphins

Answer 21

• Opioids bind to the receptors in peri-aqueductal gray area of the midbrain to block release of substance P to mute the messages after pain is alerted
• Endorphins (bodies opiate) released during sex which can decrease pain

Question 22

Gate control of pain

Answer 22

-Spinal cord receives messages from pain receptors and touch receptors e.g. rubbing stubbed toe closes gate for pain

Question 23

Placebo

Answer 23

-Placebo drugs work on emotional pain by releasing endogenous opiates

Question 24

Capsaicin

Answer 24

-Releases substance P faster than it can be resynthesized inhibiting pain messages or damaging pain receptors (pain relief)