Sodium and potassium balance (Volume regulation and diuretics) Flashcards
Where do we have baroreceptors on the low pressure side?
atria
right ventricle
pulmonary vasculature
Where do we have baroreceptors on the high pressure side?
carotid sinus
aortic arch
JGA
On the low pressure side, what happens when there is a low BP?
On the low pressure side, what happens when there is a high BP?
On the high pressure side, what happens when there is a low BP?
What is ANP?
Where is is made?
What is it released in response to?
small peptide
atria
released in response to atrial stretch
Where does ANP bind? What happens in the cell after the binding?
guanylyl cyclase domains
- causes conversion of GTP to cGMP
- protein kinase G is activated
-> cellular responses
What are the actions of ANP?
- Vasodilatation of renal (and other systemic) blood vessels
- Inhibition of Sodium reabsorption in proximal tubule and in the collecting ducts
- Inhibits release of renin and aldosterone
- Reduces blood pressure
How does the kidney respond to volume expansion?
- volume expansion
- reduced sympathetic activity
- reduced Na+ reuptake at PCT
- reduced renin production (etc -> less aldosterone) - more Na+ and water excretion
- increased ANP and BNP
How does the kidney respond to volume contraction?
- volume contraction
- increased sympathetic activity
- increased Na+ reuptake at PCT
- increased renin production (etc -> more aldosterone) - less Na+ and water excretion
- decreased ANP and BNP
Reducing Na+ reabsorption ->
______ total Na+ levels ->
______ ECF volume ->
_______ BP
reduces x3 :)
Put very simply, what do ACE inhibitors do?
reduce angiotensin 2 production
What are the effects of reduced angiotensin 2
Where on the kidney nephron do osmotic diuretics have the most effect?
PCT
Where on the kidney nephron do carbonic anhydrase inhibitors have the most effect?
PCT
Where on the kidney nephron do loop diuretics have the most effect?
thick ascending limb of LoH
Where on the kidney nephron do thiazide diuretics have the most effect?
DCT
Where on the kidney nephron do K+ sparing diuretics have the most effect?
CD
How do carbonic anhydrase inhibitors work?
block carbonic anhydrase which is involved in Na reabsorption
- carbonate ions cannot be converted into CO2
- CO2 can’t travel into cell and carbonic acid cannot be reproduced and as a result the H+ ions are not produced and exchanged for the Na+
Carbonic anhydrase activity in the kidney leads to what?
Na+ reabsorption
increased urinary acidity
How do loop diuretics work?
reduce osmotic gradient in interstitium
they block the triple transporter and as a result reduce the reuptake of LoH
Give an example of a loop diuretic
furosemide
What results from reduced reuptake of Na+ early on in the nephroni?
Increased Na+ in the distal nephron
Reduced water reabsorption
How do thiazides work?
they block the na/cl transporter (DCT)
reduce sodium uptake therefore reduced water reabsorption
