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

Fluid Balance

Anatomy & Physiology

26. Fluid and Electrolyte Balance, Acid Base Balance

Fluid Balance

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Problem L2.2

Textbook Question

A woman begins a diet and exercise regimen and loses 30 lb. Will her total body water increase, decrease, or stay the same? Why?

Verified step by step guidance

Understand that total body water (TBW) is closely related to body composition, particularly the proportion of lean body mass (muscle) and fat mass. Muscle tissue contains more water (approximately 75%) compared to fat tissue (approximately 10%).

Recognize that when a person loses weight, the composition of the weight loss matters. If the weight loss is primarily from fat, the reduction in total body water will be minimal because fat tissue contains relatively little water.

Consider that if the weight loss includes a significant amount of muscle mass (e.g., due to inadequate protein intake or excessive calorie restriction), the total body water will decrease more significantly because muscle tissue is water-rich.

Evaluate the role of hydration and exercise. If the woman maintains or increases her muscle mass through resistance training and proper hydration during her regimen, her total body water might stay the same or even increase despite the weight loss.

Conclude that the change in total body water depends on the balance of fat loss versus muscle loss. If the weight loss is primarily fat, TBW will decrease slightly. If muscle mass is preserved or increased, TBW may stay the same or increase.

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Key Concepts

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

Total Body Water (TBW)

Total Body Water refers to the amount of fluid in the body, which is essential for various physiological functions. It constitutes a significant portion of body weight and is influenced by factors such as age, sex, and body composition. Understanding TBW is crucial for assessing hydration status and the effects of weight loss on body composition.

Body Composition Changes

Body composition changes during weight loss can affect the distribution of water in the body. When a person loses weight, especially through dieting, they often lose both fat and lean mass, which can alter the proportion of water in the body. This change can lead to a decrease in total body water, particularly if the weight loss is rapid or involves significant loss of muscle mass.

Hydration and Weight Loss

Hydration plays a critical role in weight loss and overall health. During a weight loss regimen, individuals may experience changes in fluid balance due to dietary restrictions and increased physical activity. If the diet is low in carbohydrates, for example, glycogen stores deplete, leading to a loss of water weight. Therefore, understanding how hydration interacts with weight loss is essential for predicting changes in total body water.

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Related Practice

Textbook Question

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

e. Dehydration is characterized by a decreased volume and increased osmolarity of the ECF.

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Textbook Question

Which of the following statements best describes the principle of mass balance?

a. The amount of a variable that is gained by the body through ingestion equals the amount that is lost from the body.

b. The body maintains a stable mass at all times.

c. The amount of each variable brought into the body must be balanced by all other variables.

d. The amount of a variable ingested is regulated by a positive feedback loop.

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Textbook Question

As a percentage of body weight, the total body water tends to be higher in ________ and lower in ________ .

a. infants; men

b. women; men

c. men; infants

d. infants; women

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Textbook Question

How does angiotensin-II help to restore fluid balance when a person is dehydrated?

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Textbook Question

Explain how the amount of water in the body affects the concentration of ions and solutes in the ECF.

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Textbook Question

What do you think has happened to Elise's ECF volume and osmolarity over the past 3 days? Will this lead to a change in the volume of water in the cytosol of her cells? Explain.

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Multiple Choice

Most fluid in the body is in the extracellular fluid (ECF) compartment.

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Multiple Choice

The largest percentage of body water is located in what compartment?