205 L7

Question 1

Angiotensin and aldosterone

Angiotensinogen gets formed to ———— by the actions of —– which is secreted by the —– cells in the kidneys.

——– is the rate limiting factor - the more —– you have the more ——– you have.

———- gets converted into ——– by the ——– —– enzymes (ACE) in the ——–.

———- can bind to a ——(causes vasoconstriction) or ——- (reabsorption of sodium and water) receptor

Angiotensin 2 activates the —- —— exchanger on the ——- membrane as well as the —– ——— on the —— membrane. Both of these cause ——- to be ———- from the ——- lumen to the ———- space and then into the ——— and the ——– follows

There are about 95% —- receptors and 5% —— receptors, so if ———- binds to both receptors the action of the —– receptor will be expressed almost all the time

So when you inject —– or ——- you get ——— blood pressure

——– can bind to certain cells in the ———- medulla and produce ———-

———- binds to the ——— (MR) receptor and causes insertion of —— channels, which cause reabsorption of ——- into the interstitial fluid

Answer 1

Angiotensinogen gets formed to angiotensin 1 by the actions of renin which is secreted by the granular cells in the kidneys.

renin is the rate limiting factor - the more renin you have the more angiotensin 1 you have.

Angiotensin 1 gets converted into angiotensin 2 by the enzymes (ACE) in the lungs.

Angiotensin 2 can bind to a AT1 (causes vasoconstriction) or AT2 (reabsorption of sodium and water) receptors.

Angiotensin 2 activates the sodium hydrogen exchanger on the apical membrane as well as the sodium potassium ATPase on the basolateral membrane. Both of these cause sodium to be reabsorbed from the tubular lumen to the interstitial space and then into the capillaries and the water follows

There are about 95% AT1 receptors and 5% AT2 receptors, so if angiotensin 2 binds to both receptors the action of the AT1 receptor will be expressed almost all the time

So when you inject renin or angiotensin 2 you get increased blood pressure

Angiotensin 2 can bind to certain cells in the adrenal medulla and produce aldosterone

Aldosterone binds to the mineralocorticoid (MR) receptor and causes insertion of ENac channels, which cause reabsorption of sodium into the interstitial fluid

Question 2

What factors determine renin release from the granular cells in the kidney?

Answer 2

Afferent arteriolar pressure

Macula densa NaCl delivery

Sympathetic nerve activity

Question 3

Renin release

Renin promotes increased ——- —– via ———.

If blood pressure is high, there will be ——– renin release.

If blood pressure is low, there will be ——- renin release.

If there is decreased Na concentration in the —– —- cells, there will be ——- renin release.

If there is increased Na concentration in the —– —- cells, there will be ——- renin release.

If sympathetic nerve activity to the kidney increases, there will be —– renin release along with ——- of the ——- arteriole.

Answer 3

Renin promotes increased blood pressure via angiotensin 2.

If blood pressure is high, there will be decreased renin release.

If blood pressure is low, there will be increased renin release.

If there is decreased Na concentration in the macula densa cells, there will be increased renin release.

If there is increased Na concentration in the macula densa cells, there will be decreased renin release.

If sympathetic nerve activity to the kidney increases, there will be increased renin release along with vasoconstriction of the afferent arteriole.

Question 4

If there is an elevated extracellular ——— concentration you can directly regulate the release of ——– from the adrenal medulla

Answer 4

If there is an elevated extracellular potassium concentration you can directly regulate the release of aldosterone from the adrenal medulla

Question 5

What can block the actions of aldosterone?

Answer 5

Spironolactone which binds to the receptor for aldosterone

Question 6

What can block the actions of aldosterone?

Answer 6

Spironolactone which binds to the receptor for aldosterone

Question 7

What regulates Osmolality?

Answer 7

Renal water handling - ADH

Question 8

What regulates ECF volume?

Answer 8

Renal sodium handling - renin-angiotensin and sympathetic systems.

Question 9

Changes in ECF volume are compensated by changes in —- reabsorption by the kidney.

Decreased EFC volume is compensated by ——- renal reabsorption of ——– via the — —- —- system and the — — system.

Increased ECF volume is compensated by ——- renal reabsoption of ——— via decreased activity of the —— —– —- system and —- ——-

Answer 9

Changes in ECF volume are compensated by changes in sodium reabsorption by the kidney.

Decreased EFC volume is compensated by increased renal reabsorption of sodium via the renin angiotensin aldosterone system and the sympathetic nervous system.

Increased ECF volume is compensated by decreased renal reabsoption of sodium via decreased acitivity of the renin angiotensin aldosterone system and sympathetic nervous

Question 10

Changes in ECF volume are compensated by changes in —- reabsorption by the kidney.

Decreased EFC volume is compensated by ——- renal reabsorption of ——– via the — —- —- system and the — — system.

Increased ECF volume is compensated by ——- renal reabsoption of ——— via decreased activity of the —— —– —- system and —- ——-.

Also increased secretion of Atrial natriuretic peptide (ANP) by the cardiac muscle cells in the atrial wall in response to increased stretch in the atrial wall due to increased volume, reduces extracellular matrix volume by increasing sodium excretion.

Answer 10

Changes in ECF volume are compensated by changes in sodium reabsorption by the kidney.

Decreased EFC volume is compensated by increased renal reabsorption of sodium via the renin angiotensin aldosterone system and the sympathetic nervous system.

Increased ECF volume is compensated by decreased renal reabsoption of sodium via decreased acitivity of the renin angiotensin aldosterone system and sympathetic nervous.

Also increased secretion of Atrial natriuretic peptide (ANP) by the cardiac muscle cells in the atrial wall in response to increased stretch in the atrial wall due to increased volume, reduces extracellular matrix volume by increasing sodium excretion.

Question 11

Changes in ECF volume are compensated by changes in —- reabsorption by the kidney.

Decreased EFC volume is compensated by ——- renal reabsorption of ——– via the — —- —- system and the — — system.

Increased ECF volume is compensated by ——- renal reabsoption of ——— via decreased activity of the —— —– —- system and —- ——-.

Also increased secretion of Atrial natriuretic peptide (ANP) by the cardiac muscle cells in the atrial wall in response to increased stretch in the atrial wall due to increased volume, reduces extracellular matrix volume by increasing sodium excretion.

Answer 11

Changes in ECF volume are compensated by changes in sodium reabsorption by the kidney.

Decreased EFC volume is compensated by increased renal reabsorption of sodium via the renin angiotensin aldosterone system and the sympathetic nervous system.

Increased ECF volume is compensated by decreased renal reabsoption of sodium via decreased acitivity of the renin angiotensin aldosterone system and sympathetic nervous.

Also increased secretion of Atrial natriuretic peptide (ANP) by the cardiac muscle cells in the atrial wall in response to increased stretch in the atrial wall due to increased volume, reduces extracellular matrix volume by increasing sodium excretion.

Question 12

What are some Anti-hypertensive medication (high BP)?

Answer 12

irbesartan, candesartan - block AT1 receptors

Prils (ramipril, captoprils) which are the ACE (in the lungs converts angiotensin 1 to 2) inhibitors

Once this medication is consumed the blood pressure is going to be low irrespectively

Question 13

Does an increase in macula densa NaCl concentration lead to a decrease in renin secretion?

Answer 13

yes

Question 14

Does increased production of angiotensin 2 inhibit the sodium hydrogen exchanger?

Answer 14

No

Question 15

Does an increase in angiotensin 2 result in excretion of salt and water in the urine?

Answer 15

No

Question 16

What happens when you eat a lot of salt chips?

There is no change in volume.

As soon as the ——– is reabsorbed the osmolarity will ———-

This increase is sensed by the ———– in the ——— which then secrete ——–.

Increased ——- levels, increases the amount of —– retained through the signalling of ———.

This balances the osmolality

There is now an increased blood ——– which is sensed by the ———- receptors (sense how much the heart stretches). Increased blood volume, increases ——- return to the heart, these receptors fire signals which ——– sympathetic drive to the kidney which allows the excretion of —– and ——-, bringing volume back to its normal (reflex pathway - slow response).

If the increase in blood volume is substantial the ——– is going to increase. If the ——– increased then the carotid and aortic baroreceptors will sense that

Answer 16

As soon as the sodium is reabsorbed the osmolarity will increase

This increase is sensed by the osmoreceptors in the hypothalamus which then secrete ADH.

Increased ADH levels, increases the amount of water retained through the signalling of aquaporins.

This balances the osmolality

There is now an increased blood volume which is sensed by the cardiopulmonary receptors (sense how much the heart stretches). Increased blood volume, increases venous return to the heart, these receptors fire signals which decreases sympathetic drive to the kidney which allows the excretion of sodium and water, bringing volume back to its normal (reflex pathway - slow response).

If the increase in blood volume is substantial the pressure is going to increase. If the pressure increased then the carotid and aortic baroreceptors will sense that

Question 17

Does a high salt pasta meal lead to a decrease in angiotensin 2 levels?

Answer 17

Yes

Question 18

Does dehydration lead to a decrease in ADH levels?

Answer 18

No

Question 19

Is the angiotensin response to haemorrhage decreases if the renal nerves to the kidney are denervated?

Answer 19

yes

Denervated - cut,

Angiotensin 2 response to haemorrhage - decrease in blood volume, so increased renin = increase.

Response is decreased because the renin response also depends on an increase in sympathetic nerve activity to the kidney

Question 20

Does an increase in angiotensin 2 levels result in excretion of salt and water in the urine?

Answer 20

No

Question 21

Is angiotensin released by the juxtaglomerular cells when renal perfusion pressure increases?

Answer 21

No

Angiotensin is not released by the juxtaglomerular cells, renin is.

Question 22

Does stenosis of the renal artery lead to increased sodium and water reabsorption?

Answer 22

Yes

Stenosis = narrowing, when you have stenosis there is plaque build up in the artery which decreases the amount of flow to the kidney, there is decreased pressure, which increases renin, angiotensin 2 and therefore sodium and water reabsorption

Question 23

Change in blood volume

Decreased blood volume leads to ——— blood pressure.

The ——– receptors in the —- and —– and —– baroreceptors sense this change.

The cardiovascular system responds by —— cardiac output and ————.

——— intake results in increase ——- and —– fluid volume.

Both these factors ——– blood pressure.

Kidneys act to conserve —– by increased ———– —– activity, ———- of the ——- arteriole and via the —— —– —— system.

Answer 23

Decreased blood volume leads to decreased blood pressure.

The volume receptors in the atria and aortic and carotid baroreceptors sense this change.

The cardiovascular system responds by increasing cardiac output and vasoconstriction.

Water intake results in increase extracellular and intracellular fluid volume.

Both these factors increase blood pressure.

Kidneys act to conserve water by increased sympathetic nerve activity, vasoconstriction of the afferent arteriole and via the renin angiotensin aldosterone system (sodium and water retention).

Question 24

Osmolarity, Blood volume, Blood pressure

Increased osmolarity is sensed by the ———— in the ——- ——- of the ——–.

Decreased blood volume is sensed by the —– —– receptors.

Decreased blood pressure is sensed by the —- and —– baroreceptors.

—— is released which binds to —– receptors causing insertion of ——- on the tubular lumen side. This allows —— to be reabsorbed along its concentration gradient and into the capillaries.

There is increased —— reabsorption, which decreases ——–, increases blood —– and ———.

Answer 24

Increased osmolarity is sensed by the osmoreceptors in the posterior pituitary of the hypothalamus.

Decreased blood volume is sensed by the atrial stretch receptors.

Decreased blood pressure is sensed by the carotid and aortic baroreceptors.

ADH is released which binds to V2 receptors causing insertion of aquaporins on the tubular lumen side. This allows water to be reabsorbed along its concentration gradient and into the capillaries.

There is increased water reabsorption, which decreases osmolarity, increases blood volume and pressure.