Chapter 31: Kidney Disease and Diuretics (Discussion 4)

Question 1

Diuretics

Answer 1

Substance that increases rate of urine volume output

Most decrease Na+ reabsorption (and thus other solutes)

Used to decrease ECF volume

• Hypertension
• Edema
• Heart failure

Question 2

Osmotic Diuretics

Answer 2

Mannitol

Freely filtered but not absorbed substances

↑ tubular fluid osmolarity –> ↓ H2O & solute reabsorption

Question 3

Loop Diuretics

Answer 3

Furosemide

Block Na+/2Cl-/K+ cotransporter in thick ascending limb

Disrupts the countercurrent mechanism

Solutes remain in tubules –> ↓osmotic gradient –> ↓H2O reabsorption

Question 4

Thiazide Diuretics

Answer 4

Hydrochlorothiazide

Block Na-Cl cotransporter in early distal tubules

Question 5

Carbonic anhydrase inhibitor

Answer 5

Acetazolamide

Inhibits carbonic Anhydrase (mainly in proximal tubules)

Limits HCO3- reabsorption, H+ secretion

Reduces Na+

Question 6

Aldosterone antagonists

Answer 6

Competes w/ aldosterone receptor

Depress Na+-K+ pump –> ↓Na+ gradient

↓Na+ reabsorption, ↓K+ secretion (K+ sparing diuretic)

Question 7

Na+ channel blockers

Answer 7

Triamterine

Blocks Na+ channels on luminal membrane

↓Na+ reabsorption, ↓K+ secretion (K+ sparing diuretic)

Question 8

Acute renal failure

Answer 8

Extreme loss of kidney function but can return to near normal

Can cause (through H2O/salt retention):

• Edema
• Hypertension
• Hyperkalemia
• Acidosis

Sources of acute renal failure:

1. Prerenal (incoming blood supply)
2. Intrarenal (damage within kidney)
3. Postrenal (blockage of urine transport)

Question 9

Chronic renal failure

Answer 9

Progressive loss/destruction of nephrons, irreversible damage

Often caused by some initiator injury/illness

Can have normal renal function with 70-80% function nephrons remaining

Vicious cycle of decline

When # of functioning nephrons <20-30% original

• Referred to as End-stage renal disease (ESRD)
• Require external dialysis/transplant

Question 10

Prerenal Source of Acute Renal Failure

Answer 10

Decrease blood volume

Decrease CO (heart failure)

Blood diseases (septic shock, anemia)

Decrease arterial pressure

Can cause:

• Oliguria: diminished urine volume
• Anuria: complete cessation of urine output

Question 11

Intrarenal Source of Acute Renal Failure

Answer 11

Damage within kidney

Nephrons, glomerulus, tubules damage

• Acute glomerular nephritis: autoimmune reaction damaging glomerulus
• Acute tubular nephritis: tubule epithelial cells die –> clog nephron

Interstitium infection

Blood vessels damage

Question 12

Postrenal Source of Acute Renal Failure

Answer 12

(Blockage of)

Ureters (kidney stones)

Bladder

Urethra

Question 13

Vicious Cycle of Chronic Renal Failure

Answer 13

1. Initial loss of nephron function
   
   • Glomerulonephritis
   • Hypertension
   • Diabetes mellitus
2. Healthy nephrons dilate (increases output to compensate)
3. Remaining nephrons have increase in P_a/filtration/blood flow
4. Glomerular sclerosis
5. Compensating nephrons fail