25. The Urinary System

Explain the difference between filtrate and urine.

Explain how each of the drugs in question 1 from this section would lower blood pressure.

Deana is a 4-year-old girl with a rare genetic defect that causes the Na⁺/glucose symporters in the proximal tubule to reabsorb fewer glucose and sodium ions than normal. Predict the effects this defect will have on the composition and volume of Deana's urine. Explain why you would expect to see increased activity of the tubuloglomerular feedback and the renin-angiotensin-aldosterone system in Deana's kidneys.

The lowest blood concentration of nitrogenous waste occurs in the

a. Hepatic vein

b. Inferior vena cava

c. Renal artery

d. Renal vein

Predict the effects the following scenarios would have on glomerular filtration:

c. Having high arterial blood pressure (hypertension)

Angiotensin-II directly increases glomerular filtration pressure by _____________ the ___________ arteriole.

Mrs. Bigda, a 60-year-old woman, was brought to the hospital by the police after falling to the pavement. She is found to have alcoholic hepatitis. She is put on a salt- and protein-restricted diet and diuretics are prescribed to manage her ascites (accumulated fluid in the peritoneal cavity). How will diuretics reduce this excess fluid? Name and describe the mechanisms of action of three types of diuretics. Why is her diet salt-restricted?

Mannitol is a sugar that is filtered, but not reabsorbed, by the kidneys. What effect would drinking a solution of mannitol have on the volume of urine produced?

Mr. Wu is a patient with kidney disease who presents to your clinic for monitoring. You notice on his chart that his GFR was estimated through inulin administration to be about 35 ml/min. What does this tell you about the health of his kidneys? Mr. Wu is taking a medication that is normally excreted from the body in the urine. You order blood work and find that the concentration of this medication in his plasma is much higher than normal. How does his decreased GFR explain the elevated level of medication in his plasma?

How are proteins excluded from filtrate? Why is this important?