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.