Mechanisms of Renin-Angiotensin-Aldosterone System Pt 1

Welcome to Club RAAS, where you’ll get a dose of crucial information about ACE inhibitors and the elements that are responsible for the system’s regulation.

What are the things you can get out of this lecture?

  1. A better understanding of the renin-angiotensin-aldosterone system through Club RAAS.
  2. How ACE inhibitors break up the system to release fluid out of the kidneys that cause decreased heart congestion.

Let’s do it.

Club RAAS – The Bouncer

Aside from sweating, breathing, and vomiting, the best way for the body to expel waste is through the kidneys in the form of urine. Therefore, the kidneys play a very significant part in the relieving the pressure or workload of the heart by activating or de-activating the renin-angiotensin-aldosterone system.

From this moment, you can think of your kidneys as Club RAAS – a nightclub that has doors and a bouncer to guard those doors. So, at the main entrance of Club RAAS, there’s a bouncer whose primary responsibility is to monitor what goes in and out of club’s door. The bouncer’s name is Aldos-Tyrone (aldosterone). Aldosterone is an enzyme produced by the kidneys for fluid retention and control. Aldos-Tyrone is basically that guy who closes the doors to your club to make sure that nothing comes in or comes out.

            Club RAAS = Aldos-Tyrone (The Bouncer) = fluid retention and filtration control

Club RAAS – The CEO and The Assistant Managers

Next, we have the upper management that oversees the entire club – the CEO. The CEO in your Club RAAS is Mr. Renin, and he is located in your adrenal glands right above the kidneys. Mr. Renin is responsible for giving the orders or calling the shots, and he communicates with his assistant managers – Angiotensin I and Angiotensin II.

From the CEO to the assistant managers, the message to shut down the club is then conveyed to Aldos-Tyrone through a telephone system. The need to shut down the club and keep everyone inside is meant to boost revenue by selling drinks.

The CEO (Mr. Renin) -> Assistant Managers (Angiotensin I and II) -> Aldos-Tyrone (Aldosterone)

The Demographic

Apart from having control of the club’s entrance, Aldos-Tyrone is also responsible for overseeing the specific demographic that goes in first, and it’s the women. Here, the women represent sodium (NA). The moment these women enter Club RAAS, they will immediately be followed by the men. Men represent water (H2O).

The CEO is aware that the men are the ones who will buy drinks; thus increasing the revenue. For this reason, the CEO will instruct the bouncer to allow enough women in the club to have enough men to bring in revenue. So, this is the whole concept when it comes to the entire Club RAAS scenario.

      Aldos-Tyrone -> allows sodium (women) inside the club -> sodium attracts water (men)

The Concept

Sodium attracts water as women attract men. Therefore, if the body is feeling hypotensive, it will give a signal to your kidneys to increase pressure. Aldosterone will do its job by shutting down the kidneys and not let the sodium out but still allow for the sodium to come in. As the sodium increases so does the water; this will cause increased blood pressure.

If Aldos-Tyrone does not stop allowing women to go inside and not allowing them to come out, Club RAAS will reach its maximum capacity and will cause strain on its walls.

What happens if there is increased sodium inside the body?

  • Blood pressure will skyrocket
  • Pounding pulse
  • Fluid retention; weight gain

Ceasing the Pressure with ACE Inhibitors

To stop overloading the kidneys and the body with sodium and water, Aldos-Tyrone needs to be blocked, and to do so, angiotensin-converting enzyme (ACE) inhibitor is administered.

ACE inhibitors or your aldosterone receptor blocker cut the lines of communication between the CEO and Aldos-Tyrone. This basically means that you are blocking the renin-angiotensin-aldosterone system.

            Increased sodium and water = block aldosterone = use ACE inhibitors

ACE vs. ARB

ACE inhibitors or Sartans are used to block angiotensin I from being converted to angiotensin II. On the other hand, if you are specifically going to prevent angiotensin II from binding to the receptors, angiotensin-receptor blockers (ARBs) are used. The moment you block Aldos-Tyrone, you will now allow sodium to leave your kidneys and water will immediately follow. The result?

  • Decreased blood pressure
  • Decreased pounding pulse
  • Reduced jugular venous pressure
  • Reduced edema

There you have it. I hope lecture has helped you understand precisely how the RAAS works and how ACE inhibitors act on the kidneys to lower blood pressure. On our next discussion, we will be tackling calcium channel blockers.

See you there!