Renal | Micturition Reflex
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- čas přidán 16. 07. 2017
- Official Ninja Nerd Website: ninjanerd.org
Ninja Nerds!
In this lecture Professor Zach Murphy will be presenting on the micturition reflex. We talk about how the sympathetic and parasympathetic systems influence micturition, in addition to the skeletal and smooth muscles that are responsible for maintaining continence. We hope you enjoy this lecture and be sure to support us below!
References:
● Moore, K. (2018). Clinically Oriented Anatomy, 8th ed. Philadelphia: Wolters-Kluwer.
● Sam, P., Jiang, J., & LaGrange, C. (2020). Anatomy, Abdomen and Pelvis, Sphincter Urethrae. In S. [Internet], StatPears [Internet]. Treasure Island: StatPearls Publishing.
● Hall, J. (2016). Guyton and Hall Textbook of Medical Physiology. Philadelphia: Elsevier.
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#ninjanerd #MicturitionReflex #Renal
The micturition reflex.
The bladder is a muscular layer- the red coloring is the smooth muscle layer and is actually called the detrusor muscle. It is the thick muscularis layer of the bladder.
The little mucle right below the bladder is called the internal urethral sphincter. The ones closer to the deep transverse perineus muscle is the external urethral sphincter. it is a component of the urogenital diaphragm.
lets say the bladder is empty. There is just little urine in the bladder( about 10 to 20 ml of urine after urinating), this is going to be an empty bladder. what actually controls our bladder ? It is the reflexes and our CNS. the stretch receptors are located within the detrusor mucle layer and they respond to stretch. little urine in the bladder means less action potential to the spinal cord. sacrospinal cord( S2 S3 S4). The thoracolumbar part of the spinal cord ( T11 to L2).Another part of the brainstem is the pons( there are 2 centres in the pons- one is the pontine storage center and the other is the pontine micturition center). the last one is going to be the higher braincentres ans in this case this is going to be the cerebral cortex. - making you conscious. the stretching is going to be minimal stretching so little action potential in the sensory afferent neurone, so this is going to send very slow and very few action potential down the sensory neurone. 2 things will happen.
neurones are stimulated that take the sensory fibres upwards to the thoracolumbar region of the spinal cord . these synapses with pregagnlionic motor neurones located within the lateral grey horn of the spinal cord . out of the lateral grey horn, they are going to synapse on the actual cell bodies of the post ganglionic motor neurones located within a ganglia ( the inferior mesenteric ganglion). it synapses on the neurones that go out to 2 destinations. one is the detrusor muscle and the other one is the internal urethral sphincter. Now, this nerve coming out of the inf mesenteric ganglion, is a part of the hypogastric nerve. the hypogastric nerve goes to the detrusor muscle that releases norepinephrine. also this happens at the spincter. there are receptors on the detrusor muscle- specialised receptors called a beta 3 adrenergic receptor. there is little beta 2 adrenergic receptors. 97 percent is beta 3. when the norepinephrine binds to the receptor of the bladder, it causes potassium ions to leave the detrusor muscle cells, causes relaxation. in other words, it inhibit the receptors that produce kplus to leave the cell causing relaxation. on the sphincters, the receptors are called alpha 1 adrenergic receptor. this receptor, when norepineprine acts onto it causes stimulation and causes the urethra to close.
we have other nerves. In the sacrospinal cord , we have the parasympathetic nerves( pelvic nerves) the impulse will come up and activate the sympathetic activity, it comes up to the pons and stimulates it and goes up to the cortex to let it know bladder is empty. the pons has 2 centres( pontine storage centre ... the cerebral cortex will tell the pontine storage center to become activated and it will inhibit another centre - pontine micturition center. what will happen is, descending fibres come down and synapse with the preganlionic fibres that go to the inf mesenteric ganglion. its going to stimulate the sympathetic nerve that will have this flow to the hypogastric nerve, relaxing the smooth muscle of the detrusor wall and keeping the internal urethral sphincter constricted. the fibres continue coming down and stimulates the parasympathetic nerves . these come over here and goes to detrusor muscle and releases ach. these acts on specialised receptors called m3 receptors. however the parasympathetic neurones will be inhibited . if they are inhibited, the action potential that they send is very low. if that is the case they do not act on the receptors. ( when it acts normally, it causes calcium ions to go in and cause contraction). we do not want this to happen in this case. we want to keep it empty.
some fibres will synapse on those in the anterior grey horn . this is the pudental nerve. the pudental nerve is part of the somatic nervous system. it goes and acts on the nicotinic type 1receptors of the external urethral sphincter. it releases ach and cause contraction of the muscle. Gives voluntary control of that muscle.
Now, when bladder is stretched. ( 15:30 mins)
Around 200 mls is when stretch receptors become super activated and sends fast impulses. same thing happens.
you become consciously aware of the volume in your bladder. if you cant pee. your actual central centre continues to simulate pontine centre. sympathetic nerve activated. inhibit para and activates somatic nerves to keep external sphincter tight.
lets say 400 to 500 mls accumulate. it can extends to up 800 to 1000 mls it can tear above this point.
stretch receptors are going to be stimulated. this will go to the actual post grey horn. in the post grey horn, it will send impulses to thoracolumbar region but it does not synapse and passes through. ( note this part). send impulses to cerebral cortex. there are 2 centres as said above. ( pontine micturition and the other one the storage..).
cerebral cortex send down axons and synapse with the pontine micturition centre and storage centre. it stimulates the mic centre and inhibit the other one. so now, the axons will come to the thoracolumbar region of the spinal cord ( t11 to L2). they were acting on beta 3 receptors. now, they are not stimulated. impulses decrease or cease. Another one to the internal urethral sphncter will not stimulate it. No more impuslses....... not going to release norepinehrine. it will relax and urine let out. then the descending motor neurones from pontine micturition centre that go to sacral region. the parasym motor neurones. these go to detrusor muscle ( m3 receptors). now they are stimulated. these cause contraction. lots of ach is released. Contraction of the smooth muscle. this squeeze urine out of the bladder. not only that, the internal urethral sphincter relax. urine goes out. remember the somatic motor neurones that control the external urethral sphincter.( nicotinic type 1 receptor).
these are no longer stimulated. no action potential and this relaxes. it is inhibited. Urine continue to flow out and we have other muscles that can ic flow of the urine. this helps urine rush out. ( recap is at 25:22 mins of the vid)
compostiiton of urine- generally 95 percent water, little sodium, potassium, chloride, magnesium, calcium. decent amount of urea and little bit of uric acid( nucleic acid breakdown products). might be some bicarbonate present. Normally no proteins and red blood cells.
lets say the patients urine is not normal- person has glucose in urine- why is it bad? called glycosuria - ... diabtes mellitus.
if protein in urine- can be non pathological after exercise or pregnancy, can be normal.
lets say it is pathological, you have hbp or heart failure. if you have greater than 150mg/L per day- first sign of renal disease.
if ketone bodies in urine- called ketonuria. could be due to uncontrolled diabtes mellitus or due to starvation. high protein high fat diet and no carbohydrates. if you have bilirubin, bilirubinuria- sign of liver disease. ( in cirrhosis or hepatitis or die to obstruction due to gallstone).
hemoglobin in urine- had hemolytic anemia ( spherocytosis etc),
third degree burns, lots hemoglobin to be lost or mismatched transfusion
if you find red blood cells- hematuria and this is usually die to carcinoma, polycystic kidney disease. , trauma, cysts , infection , kidney stones ...can get stuck
wbcs in urine- pyuria -sign of UTI.
Thank youuu
Kahan se copy Kia?
wowww.. effort!
Mick
@@aliahsanshahid8212 kia
Thanks. Now I understand what Guyton is saying. Loool
me also
Same here.🤣🤣
Lol so true
Oooh , Guyton is pidaraz
Same!
- Philippine medical student
One day I am gonna hug y'all ninja nerd teachers! And yes after starting residency I will for sure donate. Thanks for sharing knowledge and helping us understand. You are actually helping doctors be better and save more patients. Thank you!
Hope to donate too! In the future, God willing
me too
me too
Me too
When I become a resident, I’m gonna give you a FAT donation, because you deserve it, thanks for helping me
hahah i was thinking the same thing!
Haha, I misread it as: "When I become president"
i’m hossein the reminder
Same here. He deserves a whole chunk of the bag because he's literally medschool personified
Me too
i pay 100s of dollars for professors to not teach me, and pay 0 dollars to get a full understanding of anat and physiol. Ultimately, thankful for this channel!
You are a lifesaver with our urinary system! I always search your videos because our teachers don't even lecture when it's a lecture class. They expect us to read and do questions. Not one person I talk to can learn this way. That's why we were here. When i'm done I promise to donate again.
This renal playlist helped me immensely to prepare for my exams this year. Thank you so much, brilliant teaching, amazing use of the white board, really good explanation. You deserve all the success. You are making us all better doctors, thus changing the world.
Thank you so much Prof Zach for this whole playlist.
Thank you, I just finished the complete playlist for renal, and thanks to you I understand it in a simple but detailed manner.
I'm on my last one 😀
Woaw. You are so amazing. Offering more clarity on complex subjects. Am from Ghana and have just finished this entire series today.
God richly bless you
The best medical lectures on CZcams. I swear!
Thank you so much! I especially love how you recap everything at the end 36:20 it makes understanding so much better because it revises what you just learnt! Thanks! this is amazing!
This man has very clear mind and super memory; I have seen his biochemistry videos; quite impressed on how he writes fluently very complex chemical structural diagrams; amazing!
Wow, what an education! I now have whole new respect for my urologist. I had prostate cancer about 10 years ago, which was successfully treated with external beam radiation. I'm now experiencing frequent urination. Sometimes every 10-15 minutes. I have some spinal stenosis. My urologist will be investigating that soon. My frequency varies dramatically at times. Sometimes I can as long as 2 hours.
I'm studying by your videos more than 10 hours a day thank you
You are a genius, Zach! Thank you for helping me pass my sems
you're a legend , I deeply appreciate all ur hard work , thanks for making learning fun !
Your detailed discussion really impressive and understandable for the students
Thanks for clearing the concept of the nervous control of bladder
Thanks man for your amazing lectures....
You are an absolute life saver 💫
Please add time stamp for topics ...it will be helpful
Thank you so much ..You guys have helped me through my medical year
Thank you so much for this playlist 🙌🏽🙌🏽you are a life saver....cant wait to come back and tell you I passed my physiology exams....thank you
Thank you, Professor! Best video on the subject of the micturition reflexes!
Finally I got the best video lecture on this topic. Students it is lengthy but do watch this video for once. You won't need any other reference
I have been looking at your videos and enjoying to learn lots this covid 19 lock down has taken me back by 50 years when I was undergraduate student in medical college
we are very lucky to have you Dr. Ninja Nerd
I will surely donate this generously respectful smart young man when I graduate
Great video, helping a PA student survive brother.
Really useful. It helped that you repeated the simple version and Pons as well, as some other Micturition reflex videos left that out so thank you :)
I pay thousands for med school, I swear you deserve millions.
u guys are A-MAZING!!! THANKS for you hard work!!!!
Thank you very much i understand this complex topic by this simple video🌹
who can ever dislike this
thank u thank u thaaaank u endlessly Sir
God bless you !
Watched the playlist on the kidneys, well presented, thank you!
What a guy you are Zach! appreciate the content!!!
Thanks for this better and beautiful explaination 👏
This is beautiful,thanks very much Ninja Nerds science
Thank you so much for making my med school life easier. Love lots, Rose xoxo
Nice work sir ... your videos are really helpful and the complex concepts that you simplify with so much enthusiasm is just extraordinary.. Thank you sir ..
You are a amazing teacher!
now i am your new subscriber..thank you so much... this was a very complicated topic for me.. but bundle of thanks to you Sir for such a great explanation❤️
Amazing video as usual. I can't thank you enough for your fascinating job 👏 🙌 👍
Thank you so much. This made so much sense!
Thank you.Well explained
Having no medical training, I want to express my gratitude for creating this video as I feel so much more knowledgeable of the MICTRURITION REFLEX. Now I would like to know if you have a video that explains the physiology of the pelvic floor muscles role in replacing the external sphincter as I no longer have this external sphincter due to prostate removal.
Thank u for making this video.. it helped alot...
So happy we could help you!
Phenomenal lecture as always 👌 👏 🙌 Thank you so much ❤❤
Very useful explanation with the perfect amount of detail-- I appreciate that you list the specific receptors, NT, etc. Thanks!
nice energy man! Thanks for the helpful info!
Fantastic! Thank you.
Thanks man for this serie ❤️
I appreciate your efforts ❤️
Excellent presentation!
يعطيك العافية ❤️
This was an amazing video. Thank you soo much for making this topic easier to understand. Fantastic!
We thank God for the gift in you
thank uou soooooooo much your explanation is super clair and easy to anderstand
Phenomenal lecture 👌 👏 🙌 Thank you so much ❤
Thank you so much for this!
thanks for the easy explanation
I just want to say I am almost done with my physiology course and I have been using every single one of your lectures to help me study. And because of you, I have aced every single one of my exams 😃
Thank you for the video,you were a great help! Keep up the good work :)
+Nikita ATikin I'm so happy it was helpful!!!
THANK YOU SO MUCH I REALLY APPRECIATE IT
Again topic is crystal cleared 😀
THE SAVIOUR 🔥🙏🏽
WOW... Thank you so much.
wow! great work done
Thanks sir for helping me out in the quarantine period 😀.. because all my books are in the hostel .
You have explained the complex detail of micturition reflex into a piece of cake. Ive checked some other popular videos but i found them incomplete or very short or not what i was looking for. So, thanks to you. But It would be more effective if u guys have integrated some pathological situation (as for example, neurogenic bladder) into the video. But overall, its a cool video.
+Obi Wan I'm so glad we were able to help you!!! Thank you for your kind words! Best of luck in your future endeavors!!
Ah yes, the negotiator
Now I completed complete renal physiology. I can’t express may Joyner’s after hearing these lectures
you are simply amaaaaaazing
nice video. Really help me a lot. It would be nice if this topic integrated with other pathological associated disease that affect this micturition process like bingn prostatic hyperplasia
Thank u .Great video.
oh! boy nicely explained!!!
my forever teache so thank u!!
This video was really very very useful
You are a king thank you for helping us you are a legend♥️♥️♥️♥️
thank you so much brother!
Thank u thousand times ❤❤❤❤❤❤❤
Thank you so much
I can't tell u how super u r ....u saaaaaaaaaaved my day
thank u a lot ninja u made medcine a piece of cake .
Fantastic lecture...👌👌👌
thanks big fella, appreciate it
Thank you you save my life
Great video man!! One small suggestion you cud explain then comparatively for better understanding and quick grasping..... Else you are awesome
THANK YOU SO SO SO MUCH
that's awesome sir
I find it very interesting I m paralysed patient .. and I hv problem of bladder .. will learn n spread to my paralysed patient subscriber...thank u ...
Amazing!
You’re fantastic dr 😇😇😇😇
thank you so much ❤🔥
Thank you!
Great work sir 💖
Thank you It helped a lot 👌💖
Thank you for helping me understand how head trauma can contribute to urine retention.
Zach please make do a lecture on Atonic, automatic and neurogenic bladders 🙏🏻
Please also make more videos on 2nd year .you r the best
Thank you.
Thank you