5. In the kidneys, the countercurrent mechanism involves the interaction between the flow of filtrate through the nephron loop of the juxtamedullary nephrons (the countercurrent multiplier) and the flow of blood through the limbs of adjacent blood vessels (the countercurrent exchanger). This relationship establishes and maintains an osmotic gradient extending from the cortex through the medulla’s depths, allowing the kidneys to dramatically varying urine concentration.

47. Which of these is NOT part of the splanchnic circulation?        

25.  Select the description below that illustrates the difference between a sphincter and a circular muscle.    

44. Nervous control of gastric secretion is provided by ________.        

31. Select the statement that is true concerning primary teeth.        

13. Aldosterone is a hormone that causes the renal tubules to reclaim sodium ions from the filtrate.

19. The soft palate reflexively opens the nasopharynx to allow the passage of food, which is now called a bolus.

18. Mumps is an inflammation of the parotid glands caused by a virus.

41. The lamina propria is composed of ________.        

22. Which of the following would likely be absorbed in the stomach and initial part of the small intestines?