PAIN! Physiology - The Ascending Pathway, Descending Pain Pathway and the Substantia Gelatinosa
ฝัง
- เผยแพร่เมื่อ 15 เม.ย. 2018
- Where do I get my information from: armandoh.org/resource
Facebook:
/ armandohasudungan
Support me:
/ armando
Instagram:
/ armandohasudungan
Twitter:
/ armando71021105
SPECIAL THANKS:
Patreon members
FaberCastell Australia - / fabercastellgroup
What markers do I use?
FaberCastellPITTartistpens1,5
FaberCastellPITTartistpensF
FaberCastellPermanentmarkers
FaberCastellPITTartistpensbrush
As an anesthesiologist Trainee, I've seen a lot of pain pathway explanations, but this one is by far the simplest and best
Same
True dat, helped me a lot while studying for the pain part of my anaesthesiology training!
My prof couldn't explain this in 1.5 hour. He deserves to go to jail for getting paid to do absolutely nothing.
One of the best explanations I've ever seen. Thank you!
Transcript - For easy reading!
Hello. In this video, we're going to talk about pain. We're going to focus on the ascending pathway of pain, and we're also going to talk about the descending pathway. As well we're going to focus on an area called the substantia gelatinosa. Imagine you had a right-hand injury. What happens and how do we feel pain. The pain signal coming from the site of injury will travel up to the brain, and this is where the perception of pain essentially is felt. The signal going up to the brain is referred to as the ascending pathway. Injuries to our body is felt in certain areas of our brain called the somatosensory cortex. Let's recap the brain briefly. Here's the cerebrum, brain stem, and cerebellum. The somatosensory cortex sits posterior to the central sulcus. Let's cut a cross-section of the brain like so and zoom into the somatosensory cortex. The somatosensory cortex is an area where sensations perceived, this include pain. The somatosensory cortex has areas which correlate to different parts of our body. So for example, let's look at the left side of the somatosensory cortex. The outer region here represents the leg, hand, and face. Again, this is your right side and this is your left side of the brain.
The brain continues on and joins with the brainstem, which is made up of three main components, the midbrain, pons, and medulla. These are cross-sections of the brain stem. The brain stem then continues on and becomes the spinal cord. Here we are only looking at one section of the spinal cord. Let us say this section of the spinal cord is a cervical spine area. Spinal cord has nerves coming out from the anterior root and nerves coming in from the posterior root of the spinal cord. Here I am only drawing the nerves on the right side of the spinal cord. Different tracts exists within the spinal cord. One tract important in the pain pathway or the ascending pathway is the spinothalamic tract, made up of the lateral and anterior spinothalamic tracts. Let's go back to the right-hand injury now. The right hand has an obvious injury on its palm. Within the area, there are immune cells residing. When these immune cells are damaged or should I say when any cells are damaged, including our skin cells, they start releasing cytokines - chemicals. An important one in the ascending pathway are prostaglandins represented here as PG. Prostaglandins are produced by nearly all cells, typically as a response to inflammation. Sensory nerve fibers exist all over our body. These sensory nerve fibers will respond to prostaglandins and will carry the signal or impulse to the back of the spinal cord or the Dorsal Horn of the spinal cord.
This neuron is a first order neuron. Within the Dorsal Horn of the spinal cord the first order neuron will synapse and relay this signal, this impulse, to the second neuron. This second neuron, called the second order neuron will cross over to the opposite side and will enter the spinothalamic tract. From here the second order neuron will continue up, ascending through the remaining spinal cord, through the brain stem and terminate in the thalamus of the brain. The thalamus is the relay station.
In the thalamus, the second order neuron will synapse with the third order neuron. The third order neuron will carry this impulse and relay it to the region of the brain which correlates with the injured right hand. Thus the third order neuron helps discern the area of injury and also the cortex here is where the perception of the pain is perceived. Important to remember that this is the left side of the brain, whereas the stimuli, the signal, the initial signal was on the right hand. Thus sensation always is on the opposite side of the brain to where the stimuli or stimulus occurred. Another important thing to remember is a chemical released by the first order neuron to transmit or relay the signal impulse to the second order neuron. This chemical is substance P. Thus substance P and this whole area at the Dorsal Horn of the spinal cord is an important area for the ascending pathway.
Now, whenever there is an ascending pathway, there is a descending pathway. While the ascending pathway is responsible for transmitting the pain signal up to the brain, the descending pathway is responsible for controlling and inhibiting the ascending pathway essentially. Important areas of the descending pathway include the periaqueductal gray matter of the midbrain and the nucleus raphe magnus of the medulla. When not inhibited the neurons are rising from the periaqueductal gray matter, will go down to the nucleus raphe magnus and synapse with the second neuron. This second neuron here is a serotonergic/noradrenergic neuron
And this serotonergic/noradrenergic neuron will travel down towards the Dorsal Horn of the spinal cord as well. The serotonergic/noradrenergic neuron's role in some is to inhibit or control the communication between the first order neuron and the second order neuron of the ascending pathway and thus help control pain signals going up. There is another neuron here, I'm drawing in blue, which also plays an important role in this area and we will talk about it later. So this Dorsal Horn of the spinal cord is a pretty important area. We can call it like a gate. So gate control of pain. If we zoom into this area of the Dorsal Horn of the spinal cord, it can actually be referred to as the substantia gelatinosa. So let's just recap this whole area. Here we have the first order neuron coming in and synapsing with the second order neuron here.
The first order neuron will bring in an action potential which will eventually stimulate vesicles to release its content into the synaptic cleft. The content here, in this case, is substance P. Substance P will stimulate the second order neuron. The second order neuron is stimulated and will propagate an impulse up to the thalamus via the spinothalamic tract. Coming down from the medulla, here in red, is a neuron from the descending pathway, the serotonin/noradrenaline neuron which will release its content, serotonin, and noradrenaline. These chemicals or this neuron will do two things. Firstly, it will bind on to receptors, the presynaptic neuron and inhibit the release of substance P. Second, it will stimulate a small neuron in an area called an interneuron. This interneuron in the substantia gelatinosa is actually an opioid neuron, which when stimulated will release an endogenous opioid called enkephalin. Enkephalin, like all opioids, will do two things in the substantia gelatinosa. One - it will inhibit the presynaptic neuron from releasing substance P, and two - it will inhibit the post synaptic neuron from depolarizing and thus stop the continuation of the impulse up to the thalamus. All in all, opioids such as enkephalins will inhibit the ascending pathway of pain.
So that was an overview of the ascending pathway and the descending pathway of pain.
NAssink Transcriptions
nassink.transcribe@gmail.com
I love you man
oh my.. that's very kind. :))
Thank you so much.... That was really very helpfull😇😇😇😇tysm dear 💕
Thanks dude.. Thanks a lot 😊😃
Thanks a lot ma'am. It is very helful
It´s amazing how well this is explained on such an easy-looking way... Thank you very much!
Stumbled upon your channel after a doctor in my uni used your video for a lesson in endocrine. You are a complete lifesaver, man. Kudos to you.
This was beautifully explained and portrayed. Thank you sooooooo much.
Impressive!
This is the best video explaining pain, especially the lateral inhibition.. THANK YOU
Oh my goodness, the way you explain everything so clearly and easily is amazing, this was such a big help!
I'm blown away by your teaching. Thank you so much for spending your time explaining things that have never made sense to me before! I'm on my final year and wish I found this channel beforehand. Will be sending this to everyone I know xx
Thank you! Struggled through hours of this at uni. When I watch you draw and talk it all becomes so much clearer.
I was too tired to review last night and i have a quiz this morning.
Thank you so much for this!
this eight-minute video practically equates to my professor's 1 week of discussion. Thank you very much for this! You're a brilliant angel.
Beautiful, dr Armando! Precise narration and clear diagrams drawn out at the proper time.
I mean...how intelligent and talented can one individual be? You're amazing Armando. I enjoy your videos and learn more form you than I did in school. Thank you.
It is a talent to be able to convey complex information in such a thorough yet understandable way! thank you!
you deserve a grammy award. brilliant stuff.
I've been trying to memorize the pain pathway for hours. Should've just watched this in the first place. Thank you!
wow, this guy makes it so easy to comprehend. Thank you sir.
Absolutely brilliant !! Simple and upto the point video with great hands drawn presentation
Dude! Your videos are awesome! Thank you soo much for making learning pain phsyiology easy for a visual learner like me. I keep finding myself looking for your videos when studying various topics.
Can there be anything better than this. I am sure, this is the best explanation I have ever heard. THANK YOU SIR
One of the best tutor in the world! Literally Amazing!!
FANTASTIC! drawing , details , description .. thank you so much
Really can't get a better video than this for pain pathway......❤
Omg....I needed this last week for my Neurology exam...can you do video on Nystagmus, MLF, PPRF lesions and Red Glass Test? Please
Currently in first year of med school and you have explained this better than any professor has - THANK YOU!
Amazing!!! short and sweet. Very easy to follow. This put everything together for me. Thank you for your time!!!!
Relieved my pain about pain....... thanks for your wonderful explanation and great diagrams sir🤝
AMAZING 😍 literally cleared all my doubts!
Your explanation is perfect 10/10, thank you !
I use your videos to study and they are always 100% concise and superb. Thanks a lot. My humble request is for you to make more Optometry/Ophthalmology videos (Ocular Anatomy and Physiology) Thanks in advance
thank you so much for these videos! a great A&P review so I can understand these bigger concepts!
Good explanation sir , cleared all my doubts 😊
drawing is always the best way to understand things, and yours are just awesome. You also synthesise this complex phenomenon in a very clear and simple way. to understand complex, we need to master the simple first. thank you.
This was an excellent video. I've been struggling to figure out how to explain this concept to my A&P students. Thanks so much- I will credit you and I subscribed to your channel, a first for me. Many thanks.
Awesome video. Incredibly helpful
Thanks for that!! Now I only have to reinforce the diffences between this pathway and the itch one, just little details, you helped a lot!!
This explanation helped me understand my lectures at university :) thank you so much for explaining everything so smoothly, wish u keep on doing such videos!
This explanation is amazing - so clear and easy to understand! Thank you!!!
Beautifully done. Thank you for this!
Blown away by your drawings. Keep up the good work and thank you!
This video is brilliant. Thanks for helping me understand this process!
You made it so easy to understand this concept. God bless you.
very helpful, clear and concise- thank you! Helping keeping things simple conceptually for board cert exam ;)
Love the drawings and the clarity when you explain ! Definately will be checking out your channel
You are a lifesaver! I can’t thank you enough!
Opioids like oxycodone and hydrocodone also work in another way too. 1) They inhibit signals in the ascending pathway as you mentioned. And 2) They decrease GABAergic tonic firing on the descending neuron (via Mu receptor agonism) in the periacqueductal grey which will increase neuronal firing of the descending tract.
Finally!! After watching 50 medical videos.. Your the first correct logical comment that's a real answer!!!! Thank you!! Most see just stupid doctors saying ya.... Nerves cause pain.... Now my fellow scientist.. What do you know about the pH+ values of the protein neuro transmitters?
Such an easy explaination! loved it! Cleared all my doubts
You explain this SO WELL!!
Beautifully done. You just earned another subscriber.
Thank you so much. I appreciate you sharing your knowledge and your drawing talent is amazing. Helps me to remember everything so easily...you make science easy.
omg, God bless you! this is very helpful!
Wowww! Amazing illustration!
Beautiful explanation. Thank you so much for your work.
thank you for such a wonderful teaching lookin forward for more
Thanks you so much. Blessing to you for helping others to understand it an a easy way!!!!
Brilliantly explained! Keep making please
I have no words to explian how much i am excited
Beautiful beautiful beautiful. Please don’t u ever give up on us! Ur explanation is perfect! I have A&P exam in Pharmacy school Monday. Please more please
This video is so understandable and also amusing with brilliant drawing skills
So good. Even our lecturers are recommending your videos.
Awesome. Love your visuals!
thank u dok for this video. so informative and simplified yet full of knowledge. power!
Arey yaaar such a great explaination ever... you would have got noble prize for teaching. sooo happy to see this type of explainations
Amazing explanation and super easy to understand. Thank you!
Perfect perfect ❤️ from the beautiful drawing to the perfect explanation 🌺 reallly awsome continue plz ❤️❤️
All the best
You have beautiful illustrations!! Very neat drawings..
Lovely explanation... great knowledge u have... thank u so much for explaining it sooo well!!!!
Brilliant - I love your videos, thank you so much for your very understandable ways of explaining complex subject matter.
Your explanation like that I am having I can't think my studies without you and my exams without your note and without your exam notes and my result without your knowledge thank you so much so much so so so so much may god bless you❤
You’re a life-saver! Thank you!
Wow this is an excellent explanation on pain. It was very very useful thank you
Gosh, you are a genius! I have never seen anyone so good at drawing these things! You’re an artist of physiology!
This video is golden. Thank you!!
Thank you a lot for saving my first term test.
Amazing video, thank you!
You make it so easy to understand. Thanx Armando
Thank you for clearing my topic , your teaching skills so 😊👍 good
Beautifully explained!👌👌👌
Sir TYSM.... U teaching really means a lot....🙏
Lovely! I'm a doctor already, but I'm studying now medicine in english and it's like going all over again from the begining, I mean with the words , because I didn't know how they were written or pronounced. Thank you!
Thank you so much. Very clear and uderstandable.
Thank you so much for this amazing video, I love your drawings, it's so phenominal
Best explanation ever! Thank you.
Wow this is actually incredible. excellent video
What a great art and handwriting!
Thank you for your efforts 🌸
This was very helpful for my last minute physiology revision, thank you♥
Amazing video. Loved it!!
One of the best lecture I have attended
Excellent information and explanation
Great explanation!! Easy and most needed!!! Thanks a lot sir
I'm a dental student and just found your channel !! Thank you for teaching us... something that our professors can't do ! :)
Amazing !!
Really thanks.
Thank you...that is very well explained
Beautiful presentation
It helped me to understand neuromodulation for my neuro course
Thank you so much
Beautifully explained, Subscribed!
Such a amazing explanation