During concentration of urine, urea diffuses out of and enters respectively into the:

1.	proximal tubule, descending limb of the vasa recta
2.	descending limb of vasa recta, ascending limb of the loop of Henle
3.	ascending limb of the loop of Henle, collecting duct
4.	collecting duct, ascending limb of the loop of Henle

Identify the incorrect statement regarding the micturition reflex:

1. It can be inhibited by higher centers in the brain.

2. It is stimulated by accumulation of urine stretching bladder wall.

3. can be stimulated by irritation of the bladder or urethra.

4. it is coordinated in lumbar spinal cord.

The urinary system in humans is not involved in:

1. gluconeogenesis

2. activation of vitamin D

3. regulation of leukocyte and platelet production

4. regulation of blood volume and, indirectly, blood pressure

The endocrine gland located at the superior pole of kidney is:
1. spleen
2. pancreas
3. adrenal gland
4. testes

10 to 15 distinct conical or triangular structures in the human kidney are seen in renal ______ and are known as renal ____________.

All of the following regarding juxtamedullary nephrons in human kidneys are correct except:

The part of the nephron where both hydrogen and potassium ions are secreted into the tubular fluid is the

The flow rate of filtered fluid through the kidney is:
1. glomerular filtration rate.
2. renal plasma flow.
3. filtration fraction.
4. renal blood flow.

Given that the hydrostatic pressure at the glomerulus is 50 mm Hg, the blood colloid osmotic pressure is 30 mm Hg and the capsule pressure is 20 mm Hg, the net filtration pressure would be:

1. (--) 20 mm Hg.

2. 0 mm Hg.

3. 20 mm Hg.

4. 60 mm Hg.

5. 80 mm Hg.

The GFR will be decreased if there is:
1. elevated blood pressure
2. constriction of the afferent arterioles
3. decreased blood colloid osmotic pressure
4. decreased capsule pressure