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

19. The Blood Vessels

Introduction to Hemodynamics

Anatomy & Physiology

19. The Blood Vessels

Introduction to Hemodynamics

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Problem 28

Textbook Question

Edema is a common clinical problem. On your first day of a clinical rotation, you encounter four patients who have edema for different reasons. Your challenge is to explain the edema in terms of either an increase or a decrease in one of the four pressures that causes bulk flow.
(1) First you encounter Mrs. Taylor in the medical unit awaiting a liver transplant. What is the connection between liver failure and her edema?
(2) Next in the obstetric ward, Mrs. So is experiencing premature labor and has edema in her legs. Which bulk flow pressures might be altered here?
(3) In emergency, Mr. Herrera is in anaphylactic shock. His capillaries have become leaky, allowing plasma proteins that are normally kept inside the blood vessels to escape into the interstitial fluid. Which of the bulk flow pressures is altered in this case and in what direction is the change?
(4) Finally, in oncology Mrs. O'Leary is recovering from breast cancer surgery. Her right breast and all of her axillary lymph nodes were removed. Unfortunately, this severed most of the lymphatic vessels draining her right arm. You notice that this arm is quite edematous. Why? Mrs. O'Leary is given a compression sleeve to wear on this arm to help relieve the edema. Which of the bulk flow pressures will be altered by the compression sleeve?

Verified step by step guidance

Step 1: Understand the concept of bulk flow pressures. Bulk flow across capillary walls is governed by four pressures: capillary hydrostatic pressure (CHP), interstitial fluid hydrostatic pressure (IFHP), capillary colloid osmotic pressure (CCOP), and interstitial fluid colloid osmotic pressure (IFCOP). These pressures determine the movement of fluid between the capillaries and the interstitial space.

Step 2: Analyze Mrs. Taylor's case (liver failure). The liver produces plasma proteins like albumin, which contribute to capillary colloid osmotic pressure (CCOP). In liver failure, plasma protein production decreases, leading to a reduction in CCOP. This reduction causes less fluid to be pulled back into the capillaries, resulting in edema.

Step 3: Examine Mrs. So's case (pregnancy-related leg edema). Pregnancy can increase capillary hydrostatic pressure (CHP) in the lower extremities due to the compression of veins by the growing uterus, which impairs venous return. This increased CHP pushes more fluid out of the capillaries into the interstitial space, causing edema.

Step 4: Investigate Mr. Herrera's case (anaphylactic shock). In anaphylactic shock, capillaries become leaky, allowing plasma proteins to escape into the interstitial fluid. This increases interstitial fluid colloid osmotic pressure (IFCOP) and decreases capillary colloid osmotic pressure (CCOP). The result is a net movement of fluid into the interstitial space, leading to edema.

Step 5: Consider Mrs. O'Leary's case (lymphatic obstruction). The removal of lymph nodes and lymphatic vessels impairs the drainage of interstitial fluid, leading to its accumulation and causing edema. The compression sleeve applies external pressure, increasing interstitial fluid hydrostatic pressure (IFHP), which helps push fluid back into the capillaries and reduces edema.

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Key Concepts

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

Starling Forces

Starling forces refer to the balance of hydrostatic and oncotic pressures that govern the movement of fluid across capillary membranes. Hydrostatic pressure pushes fluid out of the capillaries, while oncotic pressure, primarily due to plasma proteins, pulls fluid back in. Understanding these forces is crucial for explaining edema, as alterations in either pressure can lead to fluid accumulation in tissues.

Liver Failure and Edema

Liver failure can lead to decreased production of albumin, a key protein that contributes to oncotic pressure. This reduction results in lower oncotic pressure within the blood vessels, allowing fluid to leak into the interstitial space, causing edema. In patients like Mrs. Taylor, this connection highlights the importance of liver function in maintaining fluid balance.

Lymphatic System and Edema

The lymphatic system plays a vital role in draining excess interstitial fluid and maintaining fluid homeostasis. When lymphatic vessels are damaged or removed, as in Mrs. O'Leary's case, the drainage of interstitial fluid is impaired, leading to localized edema. Compression garments can help by increasing interstitial pressure, promoting fluid reabsorption into the lymphatic system and reducing swelling.

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