Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart3h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

26. Fluid and Electrolyte Balance, Acid Base Balance

Electrolyte Balance

Anatomy & Physiology

26. Fluid and Electrolyte Balance, Acid Base Balance

Electrolyte Balance

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3:32 minutes

Problem 23

Textbook Question

Mrs. Bush, a 70-year-old woman, is admitted to the hospital. Her history states that she has been suffering from diarrhea for three weeks. On admission, she complains of severe fatigue and muscle weakness. A blood chemistry study yields the following information: Na⁺ 142 mEq/L; K⁺ 1.5 mEq/L; Cl⁻ 92 mEq/L; Pco₂ 32 mm Hg.
Which electrolytes are within normal limits? Which are so abnormal that the patient has a medical emergency?
Which of the following represents the greatest danger to Mrs. Bush?
a. A fall due to her muscular weakness
b. Edema
c. Cardiac arrhythmia and cardiac arrest.

Verified step by step guidance

Step 1: Begin by understanding the normal ranges for the electrolytes provided in the problem. Normal ranges are as follows: Sodium (Na⁺): 135-145 mEq/L, Potassium (K⁺): 3.5-5.0 mEq/L, Chloride (Cl⁻): 98-106 mEq/L, and Pco₂: 35-45 mm Hg. Compare Mrs. Bush's values to these ranges to determine which are within normal limits and which are abnormal.

Step 2: Identify the abnormal electrolyte values. Potassium (K⁺) is critically low at 1.5 mEq/L, which is far below the normal range of 3.5-5.0 mEq/L. Chloride (Cl⁻) is also slightly below the normal range at 92 mEq/L, but not as critical as potassium. Sodium (Na⁺) and Pco₂ are within normal limits.

Step 3: Recognize the medical emergency. Hypokalemia (low potassium) is the most critical abnormality here. Potassium is essential for proper muscle function, nerve signaling, and maintaining the electrical activity of the heart. Severe hypokalemia can lead to cardiac arrhythmias and cardiac arrest, which represent the greatest danger to Mrs. Bush.

Step 4: Evaluate the symptoms in relation to the abnormal values. Mrs. Bush's fatigue and muscle weakness are consistent with hypokalemia, as potassium is vital for muscle contraction and energy production. The prolonged diarrhea likely caused excessive potassium loss, exacerbating the condition.

Step 5: Address the potential dangers listed in the problem. While a fall due to muscle weakness is a concern, the greatest danger is cardiac arrhythmia and cardiac arrest caused by severe hypokalemia. Immediate medical intervention is required to correct her potassium levels and prevent life-threatening complications.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Electrolyte Balance

Electrolyte balance refers to the proper levels of minerals in the body fluids, which are crucial for various physiological functions. Key electrolytes include sodium (Na⁺), potassium (K⁺), and chloride (Cl⁻). Abnormal levels can lead to serious health issues, such as muscle weakness, cardiac problems, and neurological disturbances. Understanding the normal ranges for these electrolytes is essential for assessing a patient's condition.

Potassium Levels and Cardiac Function

Potassium is vital for maintaining normal heart rhythm and muscle function. Normal serum potassium levels range from 3.5 to 5.0 mEq/L, and levels below 3.5 mEq/L can lead to hypokalemia, which increases the risk of cardiac arrhythmias and potential cardiac arrest. In Mrs. Bush's case, her potassium level of 1.5 mEq/L is critically low, indicating a medical emergency that requires immediate intervention.

Clinical Signs of Electrolyte Imbalance

Clinical signs of electrolyte imbalance can manifest as fatigue, muscle weakness, and changes in heart rhythm. In Mrs. Bush's situation, her severe fatigue and muscle weakness are indicative of possible hypokalemia. Recognizing these signs is crucial for timely diagnosis and treatment, as they can lead to life-threatening complications if not addressed promptly.