Kidney 3 Flashcards
What are the two main components of the nephron?
the glomerulus
renal tubule where filtered fluid becomes urine
The glomerulus and Bowman’s capsule form a united structure called the
renal corpuscle
The initial process of glomerular filtration begins
in the renal corpuscle
_____________ is the driving force that pushes fluid from the blood into the Bowman’s capsule
the net filtration pressue
The net filtration pressure is equal to
glomerular hydrostatic pressure- Bowman’s capsule hydrostatic pressure- glomerular oncotic pressure
Describe the difference between mild versus excessive constriction of the efferent arteriole.
mild constriction reduces flow towards the peritubular capillaries and increases GFR
excessive constriction reduces renal blood flow as well as GFR
Describe maximum transport.
For some substances, there’s a maximum amount that can be reabsorbed into the peritubular blood. After the maximum value is achieved, the excess substance will be excreted in the urine
Urine formation is the
sum of glomerular filtration, tubular reabsorption and tubular secretion
Urinary excretion rate is equal to
filtration - reabsorption + secretion
Where does MOST of the sodium reabsorption occur in the nephron?
a. proximal tubule
b. distal tubule
c. collecting duct
d. ascending loop of Henle
a. proximal tubule
_____________ of the filtered sodium load is actively transported out of the proximal tubule and the same amount of filtered water follows
65% (much more than anywhere else)
The following follow suit in direct proportion to sodium reabsorption in the proximal tubule
potassium
chloride
bicarbonate
The descending limb of the loop of Henle is highly permeable to
water and modestly permeable to ions
_________________ participates in the countercurrent system where the primary objective is to concentrate the urine by transferring water from the tubular fluid to the peritubular interstitium and ultimately returning it to the blood
The descending limb
______________ is impermeable to water
the ascending limb
Since water cannot follow sodium into peritubular interstitium, the ultrafiltrate
becomes more dilute and the peritubular becomes concentrated
The distal tubule is where _______ of the sodium load is reabsorbed.
5%
____________ is impermeable to water except in the presence of aldosterone or antidiuretic hormone
the late distal tubule
The following work in the collecting duct
ADH, aldosterone, & ANP
Reabsorption of electrolytes requires _________ while reabsorption of water occurs by
energy in the form of ATP; osmosis
The following are secreted into the proximal tubule by the sodium counter-transport mechanism
organic bases, acids, and hydrogen ions
The primary function of the loop of Henle is to
participate in forming concentrated or dilute urine
the loop of Henle separates
the handling of sodium & water (where sodium goes, water does NOT follow)
The osmolarity of the peritubular interstitium progressively
increases as the descending limb travels from the cortex towards the medulla
_________– adjusts urea concentration
Distal convoluted tubule
__________ regulates the final concentration of urine
Collecting duct
The collecting duct adjusts_____________- concentration
hydrogen
Where does aldosterone and ADH act on the nephron?
distal tubule & collecting ducts
Where in the nephron does parathyroid hormone promote Ca2+ reabsorption?
distal tubules
Carbonic anhydrase inhibitors work by
noncompetitively inhibiting carbonic anhydrase in the cells that make up the proximal tubule
Carbonic anhydrase inhibitors reduce the reabsorption of
bicarb, na+ & water
Carbonic anhydrase inhibitors produce
a mild hyperchloremic metabolic acidosis
Carbonic anhydrase inhibitors are used to treat
high altitude sickness
central sleep apnea
open-angle glaucoma
Osmotic diuretics are sugars that undergo
filtration but not reabsorption
Osmotic diuretics inhibit water reabsorption in the
proximal tubule (primary site) as well as the loop of Henle
With osmotic diuretics describe the ratio of water and electrolyte excretion.
water in excess of electrolytes
Osmotic diuretics transiently increase
intravascular volume
Osmotic diuretics can lead to ____________ in the patient with congestive heart failure
pulmonary edema
Loop diuretics work by
disrupting the Na-K-2Cl transporter in the medullary region of the thick portion of the ascending loop of Henle
Key complications of loop diuretics include
hypokalemia
hypocalcemia
metabolic alkalosis
ototoxicity
______________ inhibit the Na-Cl co-transporter in the distal tubule
Thiazides
Unique side effects of thiazide diuretic include
hypercalcemia
hyperuricemia
hyperglycemia
Potassium-sparing diuretics are designed to prevent
hypokalemia- but can be problematic b/c it leads to hyperkalemia which is a problem for patients who take NSAIDs, beta-blockers, or ACE-inhibitors
Examples of carbonic anhydrase inhibitors include
acetazolamide
dorzolamide
Complications of carbonic anhydrase inhibitor includes
metabolic acidosis
hypokalemia
in patients with COPD, loss of bicarb in the urine may exacerbate CNS depression from severe hypercarbia
Dose of acetazolamide:
250-500 mg
Osmotic diuretics include
mannitol
glycerin
isosorbide
______________ is a free radical scavenger
Mannitol- may limit cellular edema & decrease obstruction of renal tubules
The dose of mannitol is
0.25-1 g/kg
Clinical uses of osmotic diuretics include
prevention of AKI- little evidence to support
intracranial hypertension
differential diagnosis of acute oliguria (mannitol increases UOP if prerenal but has no effect with intrinsic injury)
