Pain

Pain is perhaps the most common human fear. A knowledge of the nature of pain can inform good nursing practice.
How is pain detected?
The skin is sensitive to touch, temperature, pressure and pain, each stimuli being detected by specific peripheral receptors. Pain is detected by a type of receptor called a nociceptor. Two basic types of pain receptor exist, they are mechano-nociceptors and polymodal nociceptors. The mechano type are activated by heavy pressure or pinching. Polymodal receptors respond to a wide range of noxious stimuli such as heat or cold and pain producing chemicals. The intensity of the stimulus determines the frequency of action potentials. This is termed frequency coding and is a major factor in how severe the pain feels.
How are painful stimuli transmitted to the brain?
Nociceptors are afferent sensory neurones. The dendrites of such fibres come together in the spinal nerves and enter the spinal cord via the dorsal horn. Their cell bodies are collected in the dorsal root ganglia. The dorsal horn is the first site of modulation. This process can effect the likelihood of an in-coming impulse being transmitted on to the brain.
From the dorsal horn some sensory impulses cross over the spinal cord to the anterior horn from where they ascend towards the thalmic region of the brain via the spinothalamic tract. Other impulses travel upwards in the dorsal column pathway on the same side of the cord. Pain may be generated in the thalamus, and pathways between the thalamus and the sensory cortex facilitate the localisation of the pain to a particular part of the body.
What types of pain exist?
Pain is commonly classified as fast or slow. Fast pain is immediate, sharp and well localised. This may occur after a needle prick and is also referred to as the first pain. Slightly later a duller or second pain is experienced, this tends to be less well localised. Fast pain is transmitted via rapid saltatory conduction in myelinated A fibres, (5 -36 ms-1) while slow pain is transmitted slowly in unmyelinated C fibres, (0.2 - 1 ms-1). Fast A fibres may initiate withdrawal reflexes while C fibres promote "guarding" and immobilising of injured parts of the body. Both mechanism therefore are designed to prevent further tissue damage.
How is pain generated?
Pain is usually classified according to its cause. These causes may include inflammation, spasm, ischaemia and irritation of serous membranes.
Inflammation
This causes pain via the mechanism of hyperalgesia which occurs as a result of nociceptor sensitization. This lowers the firing threshold of the receptors and causes previously non painful stimuli to cause pain. Insulted tissue releases so called inflammatory agents and two of these, prostaglandins and bradykinin, are known to increase nociceptor sensitivity.

[@lucindakerrigan3273]

Thank you doctor for explaining pain in such great detail. I have right now tears going down my face and may have to go to the ER. I’m traumatized from a fall and have tissue damage and my boyfriend still doesn’t understand what I’m going through. I have a pinched nerve on the SI Joint next to my right hip. I’ve had to do house chores that have caused the sciatica to now come back because I’ve surpassed my pain tolerance and threshold of pain. I’ve been diagnosed last year with more back issues in results of my last fall. Spinal stenosis, lumbar nerve root pain disorder, acute excuberation of lower back pain etc. I am also type 2 diabetic. This June I went to see a neurosurgeon in St Louis but all they want to have me do is physical therapy which doesn’t help. I was told by the ER doctor last year that I need back surgery. The past week my sciatica pain has returned possibly the radicular pain as well. My boyfriend doesn’t understand about when I get flats ups I can’t have sex or I will not only hurt worse but end up in the ER from the inflammation. I need a narcotic drug but my family doctor won’t prescribe it. I see a pain management doctor but all he gives me is gabapentin and a muscle relaxer. Tylenol and NSAIDs help very little. What do you suggest I do? I can’t just lie here another day still because I get yelled at by my boyfriend for that too. Sorry if my comments are so personal but I need help, thank you. Oh I have herniated and bulging discs too and in the past five years have fell twice and used to work in retail. Now I’m at least on SSDI thank God.

[@lixiaona]

thank you for explaining those key terms related to PAIN，　ｖｅｒｙ　ｅｄｕｃａｔｉｏｎａｌ

[@Roxy-gn8dj]

Thank you very much. I would never get board or tired of watching your awesome helpful videos. I appreciate it.

[@robertopontes9642]

Thank you for making this class. It's really great!!

[@PrabhjotKaur-rg2rn]

You made it so simple to understand! Thank you very much!

[@faridbennani1066]

Thank you sir for the precious knowledge.

[@karenjenner2470]

Excellent job.very helpful, Thank you

[@Sarahlizify]

Thanks for posting!

[@CAnon-mg1xm]

Thank you very very much.

[@Nidhi-ll3yq]

that was really good and very helpful !!! Thank you so much :)

[@maximoslowpez]

i really like your vids mate. cheers

[@elainesmyth68]

thanks john for doing your videos, it will help me with my studies ;o)

[@graviton9191]

that was useful thanks !

[@Kayce3Crush]

can you please do a video on ARDS

[@ruanpretorius9813]

hyperalgesia or hyperaglesia as spelt in video?? Thanks for the vid :D

[@Campbellteaching]

Correct, it is spelt wrong on the video, well spotted. Are you skilled in video editing per chance? I am in need of technical support.

[@lolita82288]

In the meantime, you could just note the spelling error in the video description (where you have the four questions and answers about pain) :) Thank you very much for the easy to understand explanations!

[@Kayce3Crush]

im still confused about pain modulation.

[@onegreenfly]

we hope there are subtitle on your video :\