Renal Physl 14

Question 1

What does excess sodium do?

Answer 1

• Increases plasma osmolarity
• Drives renal water absorption and thirst
• Expansion of blood volume which increases BP

Question 2

What happens when excess salt is ingested?

Answer 2

There is an increase in osmolarity causing vasopressin to be released (which increases reabsorption of water). Thirst mechanisms also increase water intake so more water is available for reabsorption

Question 3

What happens when there is an increase of extracellular fluid volume?

Answer 3

The kidneys will increase their excretion of salt and water

Question 4

What is the difference in timing of the kidneys lowering an increase in extracellular fluid volume vs cardiovascular reflexes?

Answer 4

The kidneys are quite slow while cardiovascular reflexes can lower blood pressure on the order to seconds to minutes

Question 5

What does plasma osmolarity return to normal as a result of?

Answer 5

As a result of water intake and the adjustments by the kidneys and cardiovascular system

Question 6

What is sodium balance significantly influenced by?

Answer 6

Hormonal controls

Question 7

Where is Aldosterone synthesized?

Answer 7

At the adrenal cortex

Question 8

Which part of the nephron does aldosterone work at?

Answer 8

At principal cells of the renal distal tubule and the collecting duct

Question 9

What reabsorption does Aldosterone stimulate?

Answer 9

Sodium reabsorption

Question 10

How does Aldosterone increase sodium reabsorption?

Answer 10

By increasing activity of the basolateral Na-K-ATPase

Question 11

What happens as a result of aldosterone stimulating the basolateral Na-K-ATPase?

Answer 11

Sodium is reabsorbed and potassium is excreted

Question 12

What is the mechanism of aldosterone?

Answer 12

It circulates in the blood to act at the kidneys by diffusing into principal cells and binds to a cytoplasmic receptor which stimulates transcription and translation and protein synthesis which results in Na-K-ATPase pumps on the basolateral membrane and also modulates them to speed up their action

Question 13

What is the end result of aldosterone?

Answer 13

There is increased sodium reabsorption and potassium excretion which increases blood pressure

Question 14

What stimulates Aldosterone release?

Answer 14

Low blood volume/pressure and high circulating potassium

Question 15

What cascade does low BP trigger?

Answer 15

The renin angiotensin aldosterone cascade

Question 16

What does Angiotensin II stimulate the adrenal cortex to produce?

Answer 16

Aldosterone

Question 17

How can high plasma osmolarity affect aldosterone production?

Answer 17

It suppresses aldosterone production to prevent salt from being reabsorbed

Question 18

What does a large decrease in plasma osmolarity do to aldosterone?

Answer 18

It stimulates aldosterone secretion which helps to reabsorb sodium

Question 19

How does the arterial baroreflex affect the renal sympathetic nerve activity in response to low BP?

Answer 19

It increases renal sympathetic nerve activity

Question 20

What does increased renal nerve sympathetic activity do to the juxtaglomerular cells in the kidney?

Answer 20

Cause it to secrete renin

Question 21

What does Renin do?

Answer 21

Converts angiotensinogen to angiotensin I

Question 22

What does ACE do?

Answer 22

Converts Angiotensin I to Angiotensin II

Question 23

What does angiotensin II do?

Answer 23

Acts on the adrenal cortex to stimulate aldosterone release

Question 24

What does aldosterone release do?

Answer 24

Stimulates sodium reabsorption and potassium excretion

Question 25

What does an increased sodium reabsorption caused by aldosteronedo?

Answer 25

• Increases plasma osmolarity which stimulates thirst and water intakes
• Stimulates water reabsorption

Question 26

How can angiotensin II affect the brain?

Answer 26

It stimulates vasopressin release by the hypothalamus

Question 27

What does vasopressin released by the hypothalamus do?

Answer 27

Increases renal water absorption and helps restore blood volume and pressure

Question 28

How does angiotensin II affect the vasculature?

Answer 28

It causes Vasoconstriction which increases BP

Question 29

How does angiotensin II affect sympathetic outflow at the brain?

Answer 29

It causes an increase in sympathetic output which increases cardiac output and an increase vasoconstriction and further stimulates the RAAS cascade

Question 30

How does angiotensin II act at the proximal tubule?

Answer 30

It stimulates the apical Na-H-exchanger which stimulates salt and water reabsorption

Question 31

What is the overall effect of the RAAS system?

Answer 31

It increases blood volume and pressure

Question 32

What is salt apetitie?

Answer 32

A powerful craving for salty foods when plasma osmolarity drops

Question 33

What hormones is salt appetite linked to?

Answer 33

The presence of angiotensin II and aldosterone

Question 34

What do Atrial Natriuretic Peptides do?

Answer 34

Increase sodium excretion in the urine

Question 35

What are Natriuretic Peptides released by?

Answer 35

Myocardial cells

Question 36

What is atrial Natriuretic Peptides synthesized by?

Answer 36

The cardiac atria

Question 37

When is ANP typically released?

Answer 37

In conditions of increased blood volume and pressure

Question 38

What in brain natriuretic peptide release by?

Answer 38

Ventricular myocardium

Question 39

What induces the release of Natriuretic Peptides?

Answer 39

High volume condition that cause cardiac muscle to be stretched

Question 40

How does ANP act on the kidneys?

Answer 40

It induces sodium and water excretion which helps restore blood volume and pressure back down to normal by dilating the afferent arteriole and inhibiting sodium reabsorption in the collecting duct. Also inhibits the release of sodium/water reabsorbing mediatiors