With respect to the countercurrent multiplier system when the human kidneys are producing a concentrated urine:

1.	the descending limb of the loop of Henle produces a hypotonic filtrate
2.	interaction between ascending and descending limb of loop of Henle is an example of negative feedback
3.	salt becomes recirculated and trapped in the medullary tissue fluid, increasing "saltiness" as it accumulates toward the lower tip of the pyramids
4.	water is retained in the medulla by the higher colloid osmotic pressure than that of the blood in the vasa recta capillaries

A result of secretion of ADH is that :
1. the walls of the collecting ducts become less permeable to urea and water
2. the water channels, or aquaporins, appear in the cell membranes of the collecting duct epithelial cells promoting the reabsorption of water from the filtrate
3. the ultrafiltrate flowing through the collecting duct becomes more hypotonic
4. a greater volume of dilute urine is excreted

A person with a high blood volume than normal would show:
1. increased renin secretion
2. increased aldosterone secretion
3. decreased ANP secretion
4. increased urinary ${\mathrm{Na}}^{+}$

Hyperkalemia can cause cardiac arrest. In response to hyperkalemia, the hormone secreted by human body and the site of its action are respectively:
1. aldosterone; distal tubule
2. aldosterone; proximal convoluted tubule
3. ADH; cortical collecting duct
4. ADH; proximal convoluted tubule

The renal cortex:
1. is in contact with the outer capsule
2. is divided into eight to fifteen conical renal pyramids
3. drains into the minor calyces
4. has long loop of Henle of juxtamedullay nephrons

The branch of renal artery that directly supplies the glomerulus is the:

Glomerular ultrafiltrate normally does not contain:

Identify the incorrect statement regarding antidiuretic hormone (ADH):

Diabetes insipidus:
1. is due to increased secretion or action of ADH
2. is the result of decreased insulin secretion by the pancreas
3. is characterized by polydipsia and glycosuria
4. results in the production of a large volume of dilute urine

A substance freely filtered and then completely reabsorbed by the nephron is:
1. creatinine
2. inulin
3. para amino hippuric acid
4. glucose