25. The Urinary System

The myogenic mechanism is triggered by changes in the stretch of the afferent arteriole. This is the direct result of:

The sympathetic nervous system releases _____________, which causes constriction of the afferent and efferent arterioles.

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.

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. (Connects to Chapter 17)​

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?

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.