What is Edema?

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Interstitial Fluid Filtration Formula:

Volume filtered = Volume reabsorbed + Volume removed by lymphatic system.

Describe how hydrostatic and blood colloid osmotic (oncotic) pressures determine fluid movement across the capillary walls:

Blood hydrostatic pressure moves fluid out of the blood vessel and blood colloid osmotic pressure moves blood into the blood vessels.

A person with heart failure (characterized by an inability of the heart to pump adequate amounts of blood into the arterial circulation to meet the body's needs) may have edema. What may be the mechanism causing this edema?

This edema is caused by these events: diminished blood volume pumped by the failed heart > decrease blood flow to the kidneys > this causes retention of salt and water by the kidneys > this fluid buildup leads to buildup of blood in lungs and limbs, mostly legs > this causes leakage of fluid from the legs' capillaries (tiny blood vessels) into the interstitial spaces.

A person with severe kidney failure (characterized by the inability of the kidney to form an adequate amount of urine each day) may have edema. What may be the mechanism causing this edema?

This edema is caused by these events: diminished amount of fluid released by kidneys > this causes retention of salt and water by the kidneys > this fluid buildup leads to buildup of blood in lungs and limbs, mostly legs > this causes leakage of fluid from the legs' capillaries (tiny blood vessels) into the interstitial spaces.

A store clerk works all day on her feet, and comes home each evening with swelling of her ankles. What is the mechanism of this swelling of her ankles?

This is caused by increased capillary blood pressure, hence, more fluid filtered through capillaries leading to edema.

How does reduced plasma protein cause edema?

This causes a decrease in BCOP, thus causing diminished absorption of fluid by capillaries.

A person who has liver failure cannot synthesize the normal amount of plasma proteins. How will this affect blood colloid osmotic pressure (ie, oncotic pressure)? What will be the impact on capillary filtration and reabsorption?

Liver failure results in decreased plasma proteins. See above.

Nephrotic syndrome is a kidney disorder which results in a loss of large amounts of protein in the urine. This protein in the urine has “leaked” through the kidneys, out of the blood. Patients with this condition develop oedema. Explain the mechanism by which oedema may develop:

Diminished amount of fluid released by kidneys > this causes retention of salt and water by the kidneys > this fluid buildup leads to buildup of blood in lungs and limbs, mostly legs > this causes leakage of fluid from the legs' capillaries (tiny blood vessels) into the interstitial spaces.

You fall and twist your ankle. It becomes edematous. What mechanisms may be causing this edema?

Here, capillaries have been damaged resulting in increased permeability of capillaries – that is – plasma proteins have entered interstitial fluid raising IFOP causing excess filtration.

Filariasis is a parasitic infection in the Pacific which leads to inflammation and obstruction of lymphatic vessels. What is the mechanism by which this leads to edema?

This leads to diminished volume of fluid removed by the lymphatic system leading to access filtration.

Additional Reading:

Basic Pathology

1. Cell Injury
2. Inflammation and Repair
3. Immunopathology
4. Water, Electrolyte, Acid-Base, Hemodynamic Disorders
5. Genetic and Developmental Disorders
6. Environmental Pathology
7. Nutritional Disorders
8. Neoplasia
9. Vascular Disorders
10. Heart Disorders
11. Red Blood Cell Disorders
12. White Blood Cell Disorders
13. Lymphoid Tissue Disorders
14. Hemostasis Disorders
15. Blood Banking and Transfusion Disorders
16. Upper and Lower Respiratory Disorders
17. Gastrointestinal Disorders
18. Hepatobiliary and Pancreatic Disorders
19. Kidney Disorders
20. Lower Urinary Tract and Male Reproductive Disorders
21. Female Reproductive and Breast Disorders
22. Endocrine Disorders
23. Musculoskeletal Disorders
24. Skin Disorders
25. Nervous System Disorders
26. Notes on Tissue Regeneration
27. A Table of Bleeding Disorders
28. FAQ on Structure and Function of Red Blood Cells
29. FAQ on Components of Blood
30. Notes on Hemostatic Mechanisms
31. What is Fever?
32. What is Edema?
33. FAQ on Blood Pressure
34. FAQ on principles of fluid and flow dynamics of Blood
35. Causes of Thrombocytopenia
36. Squamous cell carcinoma of head and neck mucosa
37. Four tumors which never metastasize to the brain
38. What is caustic injury?
39. What causes Peripheral Edema?

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