The Renin-Angiotensin-Aldosterone System Main Menu Restart Sources Quiz Ready to start? This tutorial will take you through the RAA System (RAAS). Here's

The Renin-Angiotensin-Aldosterone System

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Ready to start?

This tutorial will take you through the RAA System (RAAS).Here's how it's organized:This space will give you information about the pathway, and feedback on your answers. Main navigation buttons are to the left.Buttons to answer questions are to the right And the questions you are supposed to answer appear in the bar below.

Front

BackYou bet!

Not right now

http://faculty.alverno.edu/bowneps/

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http://faculty.alverno.edu/bowneps/new%20indexes/circindex.html


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But what turns it on?

The Renin-Angiotensin-Aldosterone System is one of the most important pathways in your body.

It’s part of the vital Generalized Stress Response that you use to survive injuries and emergencies.

High BP isn’t good for you, but it’s not an emergency.

Right! That needs to be fixed pronto!

That’s your rest and digest system… not an emergency.

High blood

pressure

Low blood

pressure

Para-sympathetic

system




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What organ can activate the RAAS?

Good work! The Renin-Angiotensin-Aldosterone System will turn on when your blood pressure drops.

It’s often activated by the Sympathetic System, your ‘fight or flight’ response. But it can be activated by another organ too. The first word gives you a clue.

The liver makes plasma proteins, but doesn’t turn on the RAAS.

Right! The kidneys start the RAAS

The spleen can release blood into the circulation, but not turn on the RAAS.

liver

kidney

spleen




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But how did they know the BP was low?

The kidneys won’t put up with low blood pressure, and they turn on the RAAS to fix it.

These notice low BP and alert the SNS, not the RAAS.

This is the end of the kidneys’ job. It makes more sense for them to react at thje beginning.

Right!

Central baro-

receptors

Low urine pro-

duction

Low renal blood flow




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What will the kidneys do when they sense decreased renal blood flow?

That's right! decreased renal blood flow will alert the kidneys to your decrease in blood pressure.This means that sometimes the kidneys make a mistake. If your renal arteries were blocked, for instance, the kidneys would always be turning on the RAA System, even if your blood pressure was fine.

They don’t have any muscle fibers.

This would raise BP – but it’s from the adrenal medulla.

Good work!

contract

Release epi-

nephrine

Release renin

Decreased blood flow to kidneys




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What protein does renin react with?

Right!Renin is secreted into the blood like a hormone, but it doesn't directly influence other cells. Instead, it interacts with another protein in the blood.

This is in the pathway, but we haven’t made it yet.

This is from the adrenal medulla, not made in the blood.

Good work!

Angio-tensin

epi-nephrine

Angio-tensino-

gen


Kidneys secrete RENIN into blood




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And what will it make?

That’s right! Angiotensin-ogen means ‘angiotensin maker’ – ‘gen’ as in ‘genesis’.

This is from kidneys, but it’s not part of this pathway.

This is actually used to make cheese… don’t mix it up with renin!

Angio-tensin

Erythro-poietin

rennin



RENIN reacts with angiotensinogen




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What would something called angiotensin do to raise BP?

This first angiotensin is called Angiotensin I. You will see a different kind of angiotensin later.

Look at the word again. Angio=blood vessels. Tensin=tighten

Look at the word again. Angio=blood vessels. Tensin=tighten

Right!

Increase heart rate

Increase blood

volume

Increase peripheral resistance




Angiotensin I is formed




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What do you think it will be turned into?

Right! Angiotensin I constricts blood vessels in the other tissues, so there will be a higher blood pressure in the kidneys. But it isn't a very strong vasoconstrictor, so the body turns it into another compound that is stronger.

Right!

This constricts vessels, but it isn’t related to angiotensin.

This is the compound that created the angiotensin I!

Angio-tensin II

Epin-ephrine

Angio-tensin-ogen








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What enzyme turned angiotensin I angiotensin II?

Right! Angiotensin II is a much stronger vasoconstrictor. It can raise the renal blood flow and make the kidneys happier.

This stands for anti-diuretic hormome

Right! This stands for angiotensin converting enzyme

This is atrial natriuretic factor

ADH

ACE

ANF





converted to Angiotensin II

A weak vasoconstrictor

A strong vasoconstrictor




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Where should ACE be located to process the angiotensin circulating in the blood?

Angiotensin Converting Enzyme is so important in this pathway that some people are given drugs to block it – ACE inhibitors.

A lot of your blood does go to the brain, but does all of it?

Good! All the blood from the body goes through the lungs on its next circuit

The kidneys get a lot of blood, but do they get all of it?

brain

lungs

kidneys








ACE




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But what’s happening to the other organs?

Since all the blood in your body has to return to the right heart and be sent through the lungs, ACE located in the lungs will be able to affect all the Angiotensin I.

Now that Angiotensin II has been produced and is constricting vessels and raising the blood pressure, the kidneys' problem might be solved.

Right! there still isn’t enough blood – and the kidneys are getting it!

If the vessels are constricted?

But there still isn’t enough blood – and the kidneys are getting it!

Less blood flow

More blood flow

Nothing much








ACE




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What would solve the long-term problem?

The kidneys may be happy, but the other organs may not be! This isn’t a good long-term solution.

It’s already too low – that’s why BP dropped in the first place.

You’ll need the kidneys to clean the blood.

This is really the only way, isn’t it?

Lower blood

volume

Shut down

kidneys

Raise blood

volume








ACE




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What gland could that be?

To recap: There wasn’t enough blood reaching the kidneys, so they secreted RENIN to start the RAAS.That caused angiotensin I and II to form, and those compounds constricted blood vessels, raising BP. But there still wasn’t enough blood, so now the body needs to increase blood volume.Angiotensin II starts this process by stimulating a gland just above the kidneys.

This controls a lot of blood composition, but is it near the kidneys?

Not really a gland…

Right! Adrenal means above kidneys.

Hypo-thalamus

Cerebral cortex

Adrenal cortex





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What will the aldosterone activate to increase plasma volume?

Right! The adrenal cortex stimulates an increase in blood volume by secreting ALDOSTERONE.But since the adrenal cortex doesn't have the ability to make plasma, it has to tell another organ to do it.

This moves the blood, but it doesn’t make more blood.

Right!

This makes red blood cells, but not plasma.

Cardiac muscle

Renal Na+/K+ pump

Bone marrow

Angiotensin II

Adrenal cortex releases Aldosterone




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Which way will it move these ions?

Right! The Na+/K+ ATPase in the kidneys controls the movement of ions between the urine and the blood.

Right!

That would actually decrease blood volume.

It’s an exchange pump, so it can’t do this.

3 Na+ to blood, 2

K+ to urine

3 Na+ to urine, 2

K+ to blood

Both to blood

Angiotensin II


Renal Na+/K+ pump activated




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Which way will water move?

The renal Na+/K+ ATPase is just like the Na+/K+ ATPase in your cells. It moves 3 Na+ from urine to blood and 2 molecules of K+ from blood to urine.In kidney physiology, we say the Na+ is ‘reabsorbed’ and the K+ is ‘secreted.’

Right! Water follows the solutes!

There are more solutes moving into the blood, so water will follow.

There’s a net movement of solutes into blood, isn’t there?

Into blood

Into urine

No net move-ment

Angiotensin II



3 Na+ reabsorbed into blood 2 K+ secreted into urine




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How will this movement of water and solutes into the blood change blood osmolarity (tonicity)?

Good work! When the 3 Na+ are reabsorbed into the blood, water will follow them.

This happens when blood gains solutes.

This happens when blood gains water.

Good! The blood gained water AND solutes, so its tonicity didn’t change.

Blood will become hyper-tonic

Blood will become

hypo-tonic

Blood tonicity won’t

change

Angiotensin II




Water follows by osmosis




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What will happen to blood volume?

Right! As both solutes and water enter the blood, blood tonicity will not change.

Right!

You just added salt water to the blood. How will that change its volume?

You just added salt water to the blood. Won’t that change its volume?

increase

decrease

No change

Angiotensin II








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What will happen to urine volume?

You just took salt water out of the urine. How will that change its volume?

Right!

You just took salt water out of the urine. Won’t that change its volume?

increase

decrease

No change

Angiotensin II





Blood volume increases




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What will happen to blood K+ levels?

You moved a bunch of K+ into the urine. Will there be more or less in the blood?

Right!

You moved a bunch of K+ into the urine. Won’t that change blood K+?

increase

decrease

No change

Angiotensin II






Urine volume decreases




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How will all this affect blood pressure?

Right!

You increased blood volume, didn’t you?


increase

decrease

No change

Angiotensin II







Blood [K+] decreases

Urine [K+] increases




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How will all this affect the kidneys?

They’re working hard! They need O2 to make ATP.

Right! Blood volume is up, so kidneys get more!


They’ll need less

blood

They’ll get more

blood

No change







Blood [K+] decreases

Urine [K+] increases

Blood pressure increases




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Good work! You might want to try the quiz now.


3 Na+ reabsorbed into blood




Blood pressure increases

Renal blood flow returns to normal: kidneys stop secreting renin and the RAAS stops.




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This pathway can be found in any Anatomy and Physiology text.cite this program as:Bowne, P., 2015. Renin-Angiotensin-Aldosterone System Tutorial. Retrieved on [insert today's date] from the World Wide Web at [insert the URL by which you reached this tutorial].You can contact the author at:[email protected] S. BowneBiology DepartmentAlverno College3401 S. 39th St.Milwaukee, WI 53234



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The Renin-Angiotensin-Aldosterone System Main Menu Restart Sources Quiz Ready to start? This tutorial will take you through the RAA System (RAAS). Here's