Diuretics Flashcards
What are the four function regions of the nephron?
Glomerulus
PCT
Loop of Henle
DCT
What comprises the distal nephron?
Last portion of DCT along with the collecting duct
How are the nephrons oriented within the kidney?
Upper portion of Henle’s loop is in the cortex, and the lower part is in the medulla
What are the functions of the kidneys?
Cleansing the extracellular fluid
Maintainance of acid-base balance
Excretion of metabolic waste and foreign substances
What are the three basic renal processes?
Filtration
Reabsorption
Secretion
Where does filtration occur?
At the glomerulus
What is filtration?
Non-selective and passive process: virtually all small molecules are filtered, cells and large molecules remain in blood
What are the most abundant substances in the filtrate?
Na+ and Cl-
HCO3- and K+ are also present but in smaller amounts
Which substances undergo reabsorption?
> 99% of water, electrolytes, and nutrients that are filtered
How are solutes reabsorbed?
Active transport
How is water reabsorbed?
Follows solutes and is reabsorbed through passive diffusion
How do diuretics work?
Modulating the reabsorption
How many pumps do the kidneys have for active secretion?
Two: one for organic acids and one for organic bases
What is the role of the two major pumps on the kidneys?
Promote excretion of the molecules like waste, toxins and drugs
Where are the two major pumps of the kidneys located?
In the PCT
Why are Na+ and Cl- the ions of greatest interest when it comes to reabsorption?
They are the most abundant
What is the reabsorptive capacity of PCT?
Highly reabsorptive capacity
65% of Na+ and Cl- reabsorbed at the PCT
All of bicarbonate and potassium reabsorbed at PCT
How are substances reabsorbed at the PCT?
Sodium, chloride, and other solutes –> active reabsorption
Water follows through passive reabsorption
What is the descending loop of Henle like?
Freely permeable to H2O
H2O is drawn from the loop into the interstitial space
What is reabsorption in the ascending loop of Henle like?
20% of filtered Na and Cl is reabsorbed
It is NOT permeable to water; water remains in the loop as Na & Cl are reabsorbed
What is the reabsorption of the early segment of DCT like?
10% of filtered Na & Cl is reabsorbed, water follows passively
What is the distal nephron the site of?
Exchange of Na for K and is under the influence of aldosterone
Determination of the final concentration of urine and regulated by ADH
What stimulates the sodium-potassium exchange?
Aldosterone
What is the role of aldosterone in the sodium-potassim exchange process?
Aldosterone increases the expression of the pumps responsible for sodium and potassium transport