Diuretics Flashcards
(32 cards)
What are 3 primary functions of the kidney?
- Maintain fluid balance
- Filters metabolic wastes and water
- Regulates blood volume, electrolytes, and acid-base balance
What are 3 secondary functions of the kidney?
- Secrete erythropoietin (signal = reduction in o2 to kidney)
- Secrete renin (regulates BP by causing vasoconstriction, and starts RAAS system cascade)
- Activate calcitriol (goal = increase Ca+ or Phos)
Anatomy of Kidney
Renal cortex = outer
Renal medulla = middle layer
Nephron = within the renal pyramid of the renal medulla that is the functional unit of the kidney
Nephron
2 inces long
1,000,000 within each kidney
Functional unit
Blood supply from afferent
Nephron Anatomy
Afferent = toward, efferent = away, arterioles Glomerulus = filter Filtrate = filtered fluid through Bowman's capsule Proximal convoluted tubule Descending loop of Henle Ascending loop of Henle Distal convoluted tubule Collecting duct
Filtrate
- Filtered fluid through Bowman’s capsule
- Enters convoluted tubule
- Reabsorbed at Loop of Henle
- Exits collecting duct
What are the 3 changes to filtrate?
- Reabsorption - substances move across tubule wall through interstitial fluid and enters blood at the peritubular capillary. Q 180L passing through, 178L is reabsorbed. (Na+, K+, Bicarbonate, water)
- Secretion - Away from peritublar capillary to renal tubule (H+, phosphate, ammonia)
- Excretion - Down tubule toward bladder (see video)
What is the purpose of diuretics?
Remove water/electrolytes from the body
Tx: edema, HTN, etc.
What are the 5 classes of diuretics?
- Loop diuretics
- Thiazide diuretics
- Potassium-sparing diruetics
- Osmotic diuretics
- Carbonic Anhydrase Inhibitors (CAIs)
How do loop of Diuretics work and what is an example drug?
Blocks reabsorption of Na+, Cl-, H2O in acending loop of Henle.
Ex: Furosemide - inhibits reabsorption of Na+ & Cl-, increases diuresis, excretion of K+ (adverse effect)
When would you give loop diuretics?
Tx: edema, manage HTN
What are 4 adverse effects of loop diuretics?
- Dehydration/electrolyte imbalances
- Hypotension
- Hypokalemia
- Hyperglycemia - insulin secretion decreases
How do thiazide diuretics work and an example drug? (4)
- Acts on distal convoluted tubule
- Blocks reabsorption of Na+, Cl-, K+
- Reduces preload/afterload - relaxes arterioles - ventricle pressure, reduces stretch of heart
- Reduces peripheral vascular resistance - relaxes arterioles
Example: Hydrochlorothiazide (HCTZ)
When would you give thiazide diuretics?
Tx: mild to moderate HTN, management of edema r/t HF and renal dz
What are 3 adverse effects of thiazide diuretics?
- Hypokalemia
- Hyperglycemia
- Hypotension
How is aldosterone activated?
Released by adrenal gland.
Stimulated by RAAS system via angiotensin II or kidneys sense low Na+/BP or high K+
What are the functions of aldosterone?
- Increases retention of Na+
- Excretion of K+ via urine
- Increase blood volume
- Increase BP
Where does aldosterone bind?
Binds to tubular cells in the convoluted tubule and collecting duct
What is the function of potassium-sparing diuretics and an example?
Aldosterone-antagonist - excretes Na+ and H2O; retains K+
Example: spironolactone
Why would you use potassium-sparing diuretics?
Management of HTN and edema
Counteracts K+ loss caused by other diuretics
What is an adverse effect of potassium-sparing diuretics?
Hyperkalemia
What are 4 functions of osmotic diuretics and an example drug?
- Increases osmotic pressure of filtrate
- Pulls H2O into renal tubules
- Acts on proximal tubule and descending limb
- Produces rapid diuresis
Ex: Mannitol
Why would you give osmotic diuretics?
Reduce intracranial pressure
What is an adverse effect of osmotic diuretics?
Dehydration
