pain

Question 1

pain vs nociception

Answer 1

Nociception is sensory detection of noxious stimuli (harmful)
Pain is a subjective experience that occurs if and when neurological signals reach the brain

Question 2

what is nociception

Answer 2

Nociception
Free nerve endings
Noxious stimuli release chemical mediators which trigger nociceptors and instigate inflammation

Question 3

what is the process of nociception

Answer 3

Primary nociceptive (sensory) neuron that goes into the spinal cord from the tissues (cutaneous and somatic neurons). There are two types
1. A delta fibers- sharp, fast pain sensation (first pain)- myelinated
2. C fibers- dull/ achey, slow pain sensation (second pain)- unmyelated
The secondary sensory neuron cross over to the other side of the spinal cord and then goes up the white matter tract called the lateral spinothelamic tract. It goes into the brain and synapses with the third neuron in the thalamus (the relay station for all sensory information). The thalamus relays the information to multiple parts of the brain;
1. The primary somatosensory cortex which gets signals for the location, intensity and type
2. The pre-frontal cortex where there is a rationalisation and understanding of the pain
3. Limbic system which is involved in the emotional response
Referred pain is the pain felt in body region/ tissue different to location of noxious stimuli because visceral primary nociceptors synapse with secondary neurons from somatic body areas

Question 4

neuropathic pain

Answer 4

This occurs due to nerve damage
lesion/ disease of somatosensory pathway (neurons)
- Alters neuronal signalling with pathway which can lead to;
- Pain in absence of nociception
- Pain unrelated to tissue damage but associated with other sensations

Question 5

pain perception

Answer 5

• Occurs once signals reach the cerebrum
• Pain threshold- the intensity of the stimulus required to fire action potentials at a particular rate. Very similar between individuals.
• Pain tolerance- the subjective unpleasantness of how we perceive it to hurt

Question 6

Pain modulation systems- try help and alleviate pain sensations
There are 3 main modulation systems; gate control, descending and endorphins

Answer 6

1. Gate control
   In spinal cord the nociceptive neuron comes in and synapses with the secondary sensory neuson which goes up to the brain. There is another branch that comes out of the nociceptive neuron that synapses with an interneuron- lots of neurons synapse with the internueron such as pain and somatic sensory neuron. The interneuron goes to the secondary neuron and inhibits the pain signals from going to the brain. When you stimulate pain sensations such as touch or pressure on a neuron near the pain then it decreases the pain e.g. rubbing a sore elbow when you bang it. It sends touch sensations to the brain to inhibit the pain neuron
2. Descending
   The nociceptive neuron comes into the spinal cord which synapses with the seconday nociceptive neuron and goes to the brain. Coming down from the brainstem are signals that will work with another integrated neuron near the primary neuron synapsing with the secondary neuron. The neuron coming down gets pain signals and goes to inhibit the transmission of signals between the primary and secondary nociceptive neuron
3. Endorphins (endogenous opioids)
   - Chemicals released within the pain pathway
   - They inhibit neurotransmitter release from primary neuron like the descending pathway
   - They hyperpolarize the secondary nociceptive neuron