Module Q - Fluid/Electrolytes and Acid-Base Balance

Learning outcomes for this module as of Fall 2019:

Please note: Those headings with associated teaching tips are underlined, clickable links. However, while this identifies which topics have associated teaching tips, the actual list of teaching tips you click through to include all teaching tips for this module, not only the ones for one particular topic in this module.

Topic from HAPS Guidelines (in bold font)

Learning Outcomes (indented, regular font)

Note: HAPS recognizes that there is a great deal of variability in length and depth of coverage of this topic. The learning outcomes listed below are for those courses that include significant discussion of this topic. In addition, some concepts regarding this topic may be covered instead within another module (e.g., aldosterone’s effect on the nephron is covered in Module P - Urinary System).

1. Body fluid compartments

1. Compare and contrast total body water (TBW) volumes in normal adult males and females.

2. Compare and contrast relative volumes and osmolarities of intracellular fluid (ICF) and extracellular fluid (ECF).

3. Explain the subdivision of the extracellular fluid (ECF) compartment into plasma and interstitial fluid (IF), and compare volumes and composition of plasma and IF.

4. Describe the boundary walls that separate different body fluid compartments and list transport mechanisms by which water and other substances move between compartments.

2. Regulation of body osmolarity

1. Describe the normal routes of body water entry and loss, and explain how changes in water intake/loss can disrupt osmolarity homeostasis.

2. Describe behavioral mechanisms that control water intake and loss.

3. Explain the role of hypothalamic osmoreceptors in regulation of body osmolarity.

4. Describe changes to body fluid compartment volumes and osmolarity when a person drinks a large volume of pure water, and then explain the compensatory mechanisms that attempt to restore normal volumes and osmolarity.

3. Homeostasis of blood volume, blood pressure, and body osmolarity

1. Explain what happens to blood pressure when blood volume decreases significantly due to dehydration or hemorrhage.

2. Compare changes in body osmolarity in dehydration and hemorrhage.

3. Explain how the cardiovascular, endocrine, and urinary systems monitor blood volume and/or blood pressure.

4. Explain the integrated responses of the cardiovascular, endocrine, and urinary systems to low blood pressure as a result of dehydration.

5. *Compare and contrast the compensatory mechanisms used to restore blood pressure in dehydration to those used in hemorrhage.

4. Potassium and calcium homeostasis

1. Explain the importance of maintaining potassium homeostasis with regards to membrane potential, and provide examples of dysfunction that occur when plasma potassium levels are too high or too low.

2. Describe the integrated responses of the endocrine and urinary systems to disruptions of potassium homeostasis.

3. Explain the importance of maintaining calcium homeostasis, and provide examples of dysfunction that occur when plasma calcium levels are too high or too low.

4. Describe the integrated responses of the endocrine, digestive, skeletal, and urinary systems to disruptions of calcium homeostasis.

5. Acid-base homeostasis and buffer systems

1. State the normal pH range for arterial blood and the pH range that is compatible with life.

2. Explain how changes in pH outside the normal range adversely affect body functions.

3. State the normal ranges for arterial blood P_CO2 and HCO₃^- .

4. Describe the major buffer systems of the body (e.g., bicarbonate buffer system, protein buffer system) and their locations (e.g., extracellular fluid) in the body.

5. Explain the relationship between transport of carbon dioxide in the blood and the bicarbonate buffer system in the plasma.

6. Using the equation CO₂ + H₂O ↔ H⁺ + HCO₃^- , explain what happens to pH when arterial blood P_CO2 and HCO₃^- concentrations change.

6. Integrated control of acid-base homeostasis

1. Explain the relationship between changes in alveolar ventilation (i.e., hypoventilation and hyperventilation), arterial blood P_CO2, arterial blood pH, and arterial blood HCO₃^-.

2. Explain the mechanisms by which the nephron secretes or reabsorbs hydrogen ions.

3. Explain the mechanisms by which the nephron retains filtered bicarbonate ions and makes new bicarbonate ions.

4. Define acidosis and alkalosis.

5. Compare and contrast metabolic and respiratory causes of pH imbalances.

6. Describe the concept of compensation in relation to disruption of pH homeostasis.

7. *Given arterial blood values for P_CO2, pH and HCO₃^-, determine whether a patient is in acidosis or alkalosis and whether the cause of the pH disturbance is metabolic or respiratory.

Note: An asterisk (*) preceding a learning outcome designates it as an optional, advanced learning outcome. The HAPS A&P Comprehensive Exam does not address these optional learning outcomes.