Renal 4. Integration of Salt and Water Balance

Question 1

What are the four ways to go about the integration of salt and water balance?

Answer 1

1) Renin-Angiotensin-Aldosterone Axis (RAAA)
2. Renal Sympathetic Nerve Activity
3. Arginine Vasopressin (AVP)
4. Atrial Natriuretic Peptide (ANP)

Question 2

Renin-Angiotensin-Aldosterone Axis (RAAA)

Answer 2

1) liver produced angiotensinogen (inactive)

2) glomerular cells produce RENIN
(Triggered by blood pressure increase)

3) Renin converts angiotensinogen into angiotensin I
4) angiotensin I is converted to angiotensin II by ACE (produced by capillary endothelial cells)
5) angiotensin II go to adrenal cortex = releases ALDOSTERONE (increases blood pressure via Na+ reabsorption)

Question 3

Renin Release triggers

Answer 3

1. Decrease in systemic blood pressure (sympathetic effect on JGA)
2. Decrease in NaCl concentration which is detected by the macula densa (NaCl sensor)
3. Decrease in renal perfusion pressure
   (Detected by renal baroreceptor)

Question 4

How does angiotensin II increase blood pressure ?

Answer 4

Signals the adrenal gland = produces aldosterone = acts on the kidneys:

• DECREASE Na+ excretion
• DECREASE H2O excretion

Question 5

What effect does aldosterone have on the kidney

Answer 5

1) DECREASE Na+ excretion/INCREASE Na+ reabsorption

2) DECREASE H2O excretion /
INCREASE H2O reabsorption

Question 6

DECREASE Na+ excretion/INCREASE Na+ reabsorption causes?

Answer 6

Causes more Na+ in the blood = H2O follow = more H2O in blood = INCREASES blood pressure

Question 7

DECREASE H2O excretion /

INCREASE H2O reabsorption causes?

Answer 7

Same thing as the other one .

Question 8

Does angiotensin II upregulate anything, if so what is it?

Answer 8

YES, NHE (Na/H exchangers)

Question 9

Why does angiotensin II upregulate Na+/H+ exchangers ?

Answer 9

To increase blood pressure

Question 10

How does Na+/H+ exchangers allow angiotensin to increase blood pressure?

Answer 10

In the proximal convoluted tubule.

Acts directly on the Na+/H+ exchanger on the apical side of the principle cell = increase Na+ reabsorption = increases Na+ inside the cell = taken to the basolateral listed via Na+/K+ pump ——> into blood —-> trigger release of RENIN ——> angiotensin II increase blood pressure

Question 11

How does aldosterone work?

Answer 11

Aldosterone released by adrenals glands, travels downstream, then attaches to cytotoxic receptor in principle cells within the distal tubule or collecting duct.

Question 12

Where does aldosterone attach to

Answer 12

On cytosolic cells inside the distal or collecting tubule

where water reabsorption could occur

Question 13

Once aldosterone attaches to Cytosolic receptors within the distal or collecting tubules, what does it do?

Answer 13

1) up regulate the Na/K ATPase pumps on the basolateral = increasing Na reabsorption and water will follow, = increasing blood volume = increasing blood pressure.
2) Upragulate both the Na and K channels on the apical membrane = reabsorb more Na from lumen into the cell and eventually into blood.

Question 14

If you have to much aldosterone, patients will

Answer 14

pee out a lot of K+ ions.

Question 15

What is another way to increase blood pressure by angiotensin II ?

Answer 15

Increase blood pressure = ANG II causes vasoconstriction of blood vessel = increases resistance = increases exterior pressure.

Question 16

What could trigger a need to increase blood pressure?

Answer 16

A hemorrhage or loss of blood volume would cause blood pressure to decrease as well, and needs to be returned back to normal

Question 17

2. Renal Sympathetic Nerve Activity has both

Answer 17

Direct and indirect effects

Question 19

2. Renal Sympathetic Nerve Activity

Direct effects

Answer 19

1. Increased renal vascular resistance = decreased RPF/GFR = increased Na+ retention in the blood
2. Increased Na+ reabsorption by proximal tubule cells (increased NHE and Na-K Pump)

Question 20

3. Arginine Vasopressin (AVP)

Answer 20

Increased Plasma Osmolality Stimulates Osmoreceptors in the Hypothalamus to Trigger the Release of
Arginine Vasopressin, Which Inhibits Water
Excretion (ANTIDIERETIC)

Question 21

Where does arginine vasopressin function to inhibit water excretion

Answer 21

On the thick ascending limb and the collecting tubules, through Na+

Question 22

HOW does arginine vasopressin function to inhibit water excretion ?

Answer 22

It upregulates the Na/K/Cl co transports on the apical side of the THICK ascending limb and collecting tubule = Increases Na+ going through the cell and out into the blood. = this will causes H2O to follow it into the blood ——> reduce water excretion !

Question 23

4. Atrial Natriuretic Peptide (ANP)

Major effects are

Answer 23

hemodynamic:

Question 24

4. Atrial Natriuretic Peptide (ANP)

• Major effects are hemodynamic:

Answer 24

Renal vasodilation = increased blood flow:

Question 25

How does ANP cause renal vasodilation = increased blood flow =

Answer 25

Decreases blood pressure

Question 26

ANP is the only one that acts in

Answer 26

kidneys to reduced blood pressure when there’s an increase in blood pressure.

Question 27

ANP released by the walls of the

Answer 27

atrial muscles.

Question 28

What’s is ANP triggered by how is it released?

Answer 28

Triggered by an increase in blood pressure = walls of atrial muscles stretch = released ANP = renal vasodilation = increased blood flow (2 consequences)

Question 29

What are the two 2 consequences of increasing blood flow via ANP?

Answer 29

1. Increased GFR

2. Increase blood flow in vasa recta

Question 30

1. Increased GFR =

Answer 30

removing more Na out of the blood by filtering it, water follows = blood pressure decreases

Question 31

2. Increase blood flow in vasa recta =

Answer 31

washout the gradient in the medulla = around 800 mOsm instread of 1400 = less H2O reabsorbed = reducing blood volume = reducing blood pressure

Question 32

2. Renal Sympathetic Nerve Activity

Indirect Effect:

Answer 32

1. Increase Renin release = increases blood pressure