Renin Angiotensin Aldosterone System 2/7

Renin Angiotensin Aldosterone System 2/7


Comes here of this bend. This is the end of,
this is the beginning of distal congulated tubule and end of the thick part of ascending
limb of loop of henle. Here nature has put a very beautiful system. There are some cells
here which are very very slightly modified structure, this group of cells here the nephron
cells are somewhat modified. These are tall, these are dark looking and these cells love
to taste the fluid here, these cells are sensitive to, they are sensitive to sodium they are
sodium sensors. What is the function of these cells? These are sodium sensing cells. Right?
Now, actually this is pressure sensing system and this is sodium sensing system. This system
together makes a whole appratus. Now look, afferent arteriole with polkesin and this
specialized group of cells from distal congulated tubule and its junction with the proximal
part. Is that right? This group of cell and this group of cell they make one specialized
apparatus. These acting as a baroreceptors and these acting as chemoreceptors. These
are the baroreceptors, these are the chemo receptors. They measure the blood pressure,
they measure the sodium concentration. Is that right? and they are held together by
some connective tissue cells. They are held together by some yes? connective tissue cells.
Now! I told you this blood pressure measuring device, baroreceptor group it is called “Polkesin”
and this sodium sensing device it is present in every nephron, it has a special name. You
know what is the name of these special group of cells? Which measure the sodium. Thank
God the researcher who found it he did not put his name on this. Actually in the beginning
when researchers looked at the nephron structure they found this area was little bit more dark
as compared to the rest of the nephron. These group of cells were darker. So they just called
it “Macula Densa”. That there is some macule, macule means patch, patch of cells which is
looking very dense. So this is called, what is name of this thing? “Macula Densa”. Now
Polkesin is from afferent arteriole and Macula Densa is from distal congulated tubule, this
is vascular component and this is nephron component. This is pressure measuring device
and this is sodium measuring device and they are held together through connective tissue
cells which are called “Lacis cells”. All this apparatus as a group is present in every
neprhon. It means every nephron has blood pressure measuring device as well as sodium
measuring system and as a group polkesin + macula densa they are given a very special
name and all of you know that name. What is the name of this apparatus? Yeah! “Juxtaglomerular
apparatus”. Have you heard of it? So this is juxtaglomerular apparatus. Just they call
it a special apparatus. Right? juxta posed to glomerulous. juxtaglomerulous with the
glomerulous there is a very special apparatus. Thank God they did not put a very complex
name for it. They just say there is special apparatus, they never knew in the beginning
what is its function. Now they know, Now! Lets go back to our analogy. We were saying
that the person is bleeding blood pressure is going down, blood flow is going yes? down!
So when blood flow is less baroreceptors are activated in juxtaglomerular apparatus and they release “Renin”. Meanwhile
when your blood flow is less then glomerular filtration is more or less? Less of course!
If there is less blood coming. Right? Then filtration is also less. Now you think really
with your own cortex. That, if filtration is very less, listen listen 😀 if filtration
is very less the fluid will move through this lumen rapidly or slowly. Sure? So whenever
GFR is less luminal flow becomes slow. When movement of the fluid from the lumen becomes
slow then what happens? These cells which are working on this luminal fluid. They have
more chance to work or less chance to work? More my friend… Of course, Look! If there
are many mangoes going here attention Mr. Hadayat lets suppose there is water going
and lot of mangoes going here and you are sitting here to catch the mangoes. If flow
is very fast you will miss the mangoes but if it very very slowly coming you will catch
every mango. Did you get it? These cells work like you! They are not catching mangoes there,
they are catching sodium there. So when blood pressure becomes less, glomerular filtrate
becomes less. Luminal flow becomes less. These cells extract extra-ordinary amount of sodium
and by the time the little fluid reaches here it is more than normal amount of sodium or
less than normal amount of sodium? Less than normal amount of sodium. Then macula densa,
it loves to taste sodium so whenever GFR is less the proximal part of nephron works on
the slowly moving fluid, extract too much sodium so less sodium reaches the sodium sensing
device and whenever macula densa feels there is less sodium coming it becomes super active.
It is activated when there is less sodium reaching here and it releases some nitric
oxide is released by it and prostaglandins are released by it and they activate these
polkesin cells. Macula Densa requests this that “Please” listen to us! There is very
little sodium coming here. There is something wrong with GFR. Probably blood is not coming
well. So please release more “Renin”. So renin release becomes further augmented. So now
renin has been released under two influences. Under “Pressure change” and under “Sodium
change”. So every glomerulous has juxtaglomerular apparatus. Apparatus consists of blood pressure
measuring device and apparatus consists of sodium sensing device. Blood pressure measuring
device is derived from the afferent arteriole smooth muscle, sodium measuring device is
a derivative of nephron cells. Together they make “juxtaglomerular apparatus”. Whenever
blood flow is less to the kidney. Right? This apparatus releases excessive renin in the
blood. Now what this renin should do? Renin should “Correct” the balance. Bring the patient
out of tragedy. What was the tragedy? Blood pressure was going down and blood volume was
going down. Now function of renin is to bring the blood pressure back as well as blood volume
up. So that patient does not die. For example, patient has lost 1 liter of blood than somehow
blood pressure should be maintained and somehow blood volume should be maintained. We will
talk about how renin does it but before that we will talk about one more factor. What is
that? That is, that whenever your blood pressure goes down, lets suppose here is your heart.
So what really happens? What is it? What is this? Carotid system has carotid body. What
is the function of…”SORRY” Carotid Sinus not carotid body. This what I am saying is
“Carotid Sinus”. Carotid sinus is another “Blood pressure measuring device”. It also
has baroreceptors. When patient is bleeding, the blood flow to the kidney is more or less?
Less! So whenever blood flow becomes less, this carotid system is also activated and
special neurons they report to the central nervous system that blood pressure is falling.
They report to the central nervous system that blood pressure is falling. In the central
nervous system, Right? Ok, Lets forget about this part of the diagram 🙂 and concentrate
only on this. This is going into peritubular capillaries and than it collects back as venous
blood. Ok connect it here. This was renal arterial flow and this is renal venous flow.
Venous blood going back. Right? and arterial blood.

84 Replies to “Renin Angiotensin Aldosterone System 2/7”

  1. omg..i want you to be my professor..i am in canada..n want to tell u man u teach way better than any of those..hats off to BROWN BRAIN..

  2. Nice…this guy can put together a solid lecture. Very, very helpful and in terms most can understand! Mango catchers!

  3. Amazing!! I have a Patho exam coming up in 10 days… I love your clear teaching style! Finally I am seeing the light! Totally love the mango theory.. I know it will make me laugh in the exam when I try to figure out Na concentrations. Wonderful teaching!

  4. think ive taken more notes watching your first two videos on RAS system then I have in the first 5 weeks of uni

  5. Oh man! I was SCREAMING out JGA! JGA! JGA! This guy rocks. I wish I could skip the thousands of dollars of debt from college, pay a few hundred for a comprehensive list of videos like this, and end up with a BETTER education. Seriously.

  6. even if my english is not perfect, it´s still the best source of physiology info I´ve ever found. It sounds so clearly and simple, next to a few diagrams, which made our professor.. Thanks so much from Czech republic

  7. @rmcdaniel423 , SAME HERE! I'm in grad school (private Catholic college with med school too) attaining my Adult Nurse Practitioner. It's costly and I don't learn a thing from the boring lectures recorded and played on Real Player. Absolutely NO teaching, just reiterating the text. I'm disgusted with it, but it is an online course which I need living in Alaska.

  8. Dr. Najeeb you have helped me so much. I am studying to be a Paramedic and your videos will get me through the course with no problems.
    Thank you, much appreciated!

  9. Where have you been all my life!? I think I love u 😀
    Thank you for referring to "nature" as source instead of god so that we can focus on the science instead of personal faith. I dont know if anyone else feels this way but I'm really annoyed with teachers repeatedly reference creation perhaps unknowingly by saying god made this and that.

  10. really a'm so happy ..i got u dr. what a explanation .mind blowing …very helpful for us..love it…thanks.

  11. This video has been soooo educational and entertaining. I'm watching just before taking my comprehensive final and wish I had found it earlier. So helpful and easy to comprehend information that I could NOT seem to grasp before. Thank you. 🙂

  12. Amazing
    Wished only if Dr. Najeeb realized that there is a creator for all these miracles in the human body not the nature.

  13. Professor Najeeb is the best! He has a way to always explain himself, something that not all professors have; in fact, it's very rare.

  14. Yes, you're right. He is an amazing teacher. I just wish you could realize that there's no creator but nature for all these miracles.

    Why should there be a creator?

  15. Please correct the spelling It`s Polkissen sir not pokision
    and Renin also called as angiotensinogenase is an enzyme not a hormone like you said in the lecture.
    Regards

  16. You are amazing!!! You might have just reignited my passion for learning and for medicine and for kidneys especially (LOVE them!!!). Simply amazing. Your passion is contagious. Thank you. 

  17. talented teacher he make the complex easy and in happy and sweet way congratulation prof najeeb you deserve your name

  18. Thank you Dr. Najeeb! Really great explanation of the RAA System! I do have one question though (open to anyone who knows the answer). My text says that the descending limb of the loop of Henle is solely responsible for water reabsorption, while the ascending limb only reabsorbs ions and no water. If this is true, wouldn't the mango analogy refer to water reabsorption, and not Na+ reabsorption? Any clarification would be really appreciated. Thanks again!!!

  19. OMGosh!  You're explanations are so easy to understand.  Love the "mango" explanation.  I now understand a lot more of how renin is produced by the reduction in blood pressure!!  Thank You, this will help me so much in my Nursing Exams.  Very much appreciated

  20. at 6:55 when the sodium sensing cells tell the polkesin cell to release Renin, polkesin cells are already releasing but when they are told by sodium sensing cells then more Rening is released into the blood right? is it positive feedback mechanism playing there?

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    open this link and type 1096690 as ambassador id and click on apply
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