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 18

Textbook Question

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

Verified step by step guidance

Understand that dehydration leads to a decrease in blood volume and blood pressure, which triggers the renin-angiotensin-aldosterone system (RAAS) to restore fluid balance.

Recognize that angiotensin-II is a key hormone in the RAAS pathway, produced when renin (from the kidneys) converts angiotensinogen (from the liver) into angiotensin-I, which is then converted to angiotensin-II by the enzyme angiotensin-converting enzyme (ACE) in the lungs.

Explain that angiotensin-II acts as a potent vasoconstrictor, narrowing blood vessels to increase blood pressure and improve circulation despite reduced fluid levels.

Describe how angiotensin-II stimulates the release of aldosterone from the adrenal glands, which promotes sodium reabsorption in the kidneys. Sodium reabsorption increases water retention, helping to restore blood volume.

Highlight that angiotensin-II also stimulates the release of antidiuretic hormone (ADH) from the posterior pituitary gland, which increases water reabsorption in the kidneys, further aiding in fluid balance restoration.

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Key Concepts

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

Angiotensin-II

Angiotensin-II is a peptide hormone that plays a crucial role in the body's fluid balance and blood pressure regulation. It is produced from angiotensinogen in response to low blood pressure or low blood volume. Angiotensin-II acts primarily by constricting blood vessels, which increases blood pressure, and stimulating the release of aldosterone, promoting sodium and water reabsorption in the kidneys.

Fluid Balance

Fluid balance refers to the equilibrium between the intake and output of fluids in the body, essential for maintaining homeostasis. When a person is dehydrated, the body loses more water than it takes in, leading to a decrease in blood volume and pressure. Restoring fluid balance involves mechanisms that increase water retention and promote fluid intake, ensuring that vital organs function properly.

Aldosterone

Aldosterone is a steroid hormone produced by the adrenal glands that regulates sodium and potassium levels in the body. In response to angiotensin-II, aldosterone promotes the reabsorption of sodium in the kidneys, which in turn leads to water retention. This process helps to increase blood volume and restore fluid balance, particularly during states of dehydration.

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Textbook Question

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

d. Atrial natriuretic peptide promotes water retention in the kidneys and increases the amount of water in the body.

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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

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

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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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