25. The Urinary System

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

Fill in the blanks for the following statements:

a. When the GFR decreases, the macula densa releases chemicals to______ the afferent arteriole.

b. The sympathetic nervous system______ the blood vessels supplying the kidney _____ to the glomerular filtration rate.

c. The enzyme _____ is released by JG cells in response to a decrease in the GFR.

d. The enzyme ______ converts angiotensin-I to angiotensin-II.

e. Generally, angiotensin-II______ systemic blood pressure while _____ the GFR.

Describe the mechanisms of extrinsic regulation of GFR, and their physiological role.

Describe the mechanisms that contribute to renal autoregulation.

Which of the following is/are true about ADH?

a. It promotes obligatory water reabsorption

b. It is secreted in response to an increase in extracellular fluid osmolality

c. It causes insertion of aquaporins in the PCT

d. It promotes Na⁺ reabsorption

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?

Explain the difference between filtrate and urine.

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

c. Having high arterial blood pressure (hypertension)

Drugs that treat hypertension, or high blood pressure, have the following actions. Discuss the specific effect that each drug will have on the kidneys.

a. Blocking the action of aldosterone on the kidneys

Drugs that treat hypertension, or high blood pressure, have the following actions. Discuss the specific effect that each drug will have on the kidneys.

b. Blocking the receptor for angiotensin-II on blood vessels and in the renal tubule cells

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

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?