1. Fluid, Electrolyte, and Acid-Base Balance26
Fluid, Electrolyte, and Acid-Base Balance

2. plasma; interstitial fluid adipose; skeletal muscle
The two main fluid compartments within the body are _________ and _________.
plasma; interstitial fluid
adipose; skeletal muscle
intracellular fluid; extracellular fluid
blood; cytoplasm
Answer: c. intracellular fluid; extracellular fluid

3. The most abundant cation of the ECF is _______ and the most abundant anion in the ECF is _______.
K+; HPO42–
Mg2+; HCO3–
Ca2+; SO42–
Na+; Cl–
Answer: d. Na+; Cl–

4. Insensible perspiration Sweating Defecation Tears
Which of the following accounts for the most water loss, second only to urine output?
Insensible perspiration
Sweating
Defecation
Tears
Answer: a. Insensible perspiration

5. Which is the most potent stimulus for thirst?
Dry mouth
An increase in plasma osmolarity
An increase in blood volume
The sight of a cold drink
Answer: b. An increase in plasma osmolarity

6. thirst is continuously communicated to the brain.
You were thirsty and drank a full glass of water only to have your thirst return an hour later. This is because:
thirst is continuously communicated to the brain.
the kidneys produced a large volume of urine.
distension of the stomach temporarily inhibits the thirst center.
the stomach absorbs water slowly.
Answer: c. distension of the stomach temporarily inhibits the thirst center.

7. When ADH levels are low, the kidneys produce _________ urine.
dilute
concentrated
a low volume of
isotonic
Answer: a. dilute

8. An overheated marathon runner accepts cups of plain water at each refreshment area. When the race ends, the runner is very disoriented and collapses. What is the best explanation for her condition?
The runner overexerted herself.
The runner needs more water because she is dehydrated.
The runner is suffering from hypotonic hydration and her cell fluids are overdiluted.
The runner’s ICF is hypotonic to her ECF.
Answer: c. The runner is suffering from hypotonic hydration and her cell fluids are overdiluted.

9. Diabetes mellitus, which causes excessive urine output
What might be a probable explanation for an intense craving for heavily salted food?
Diabetes mellitus, which causes excessive urine output
Addison’s disease, in which insufficient aldosterone is available to reabsorb NaCl from the filtrate
Diabetes insipidus, which is manifested by hyposecretion of ADH
Hypersecretion of aldosterone
Answer: b. Addison’s disease, in which insufficient aldosterone is available to reabsorb NaCl from the filtrate

10. Water solubilizes salt.
Which of the following statements best summarizes the relationship between the sodium content of fluids and water movement?
Water follows salt.
Salt follows water.
Water equals salt.
Water solubilizes salt.
Answer: a. water follows salt

11. Which two hormones are essential for reabsorption of water at the collecting duct?
Renin and aldosterone
ADH and aquaporin
Aldosterone and ADH
ADH and renin
Answer: c. Aldosterone and ADH

12. Blood sodium levels are indirectly assessed by __________.
sodium chemoreceptors
chloride chemoreceptors
baroreceptors
PH receptors
Answer: c. baroreceptors

13. The _______ contains the largest percentage of water in the body.
extracellular fluid
intracellular fluid
blood plasma
lymph
Answer: b. intracellular fluid

14. You would expect blood levels of ANP to increase when __________.
blood pressure is increased
blood Na+ is elevated
the walls of the atria are stretched
all of the above occur
Answer: d. all of the above occur

15. A patient suffering from hyperthyroidism may experience heart malfunction. Consequently, this patient must also tightly regulate his potassium intake. Which of the following is the best explanation for why he must carefully watch dietary potassium?
Even slight changes in K+ are not detectable by the heart.
Both hyper- and hypokalemia can disrupt electrical conduction in the heart.
The kidney is unable to excrete K+ in someone with hyperthyroidism.
Dietary intake of K+ causes hyperthyroidism.
Answer: b. Both hyper- and hypokalemia can disrupt electrical conduction in the heart.

16. PTH stimulates osteoclasts to resorb bone.
PTH affects calcium blood levels via which of the following mechanisms?
PTH stimulates osteoclasts to resorb bone.
PTH stimulates increased Ca2+ absorption in the intestine.
PTH stimulates increased Ca2+ reabsorption by renal tubules.
All of the above are ways PTH affects calcium blood levels.
Answer: d. All of the above are ways PTH affects calcium blood levels.

17. Brain stem respiratory centers Lactic acid production
Which of the following is the initial H+ regulatory mechanism in the body?
Renal excretion
Chemical buffers
Brain stem respiratory centers
Lactic acid production
Answer: b. Chemical buffers

18. Which of the following is the major ECF buffer system in the body?
Bicarbonate buffer system
Phosphate buffer system
Protein buffer system
Sulfate buffer system
Answer: a. Bicarbonate buffer system

19. The pH would remain unchanged.
How might the pH of the intracellular fluid change when cells increase their rate of metabolism?
The pH would decrease.
The pH would increase.
The pH would remain unchanged.
The pH would change proportionately to the amount of bocarbonate produced.
Answer: a. The pH would decrease.

20. The respiration rate would increase.
If the blood pH lowers, what change would you expect from the respiratory system?
The respiration rate would increase.
The respiration rate would decrease.
The respiration rate would remain unchanged.
The respiration rate would be erratic.
Answer: a. The respiration rate would increase.

21. In the collecting ducts, bicarbonate ions are generated by_______ cells, while ________ cells secrete bicarbonate ions.
PCT; DCT
Type B; Type A
collecting duct; PCT
Type A; Type B
Answer: d. Type A; Type B