What is Fever?

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How does infection cause fever?

During infection, phagocytes ingest certain bacteria and secrete a pyrogen (eg., interleukin-1) and this pyrogen circulates to the hypothalamus that induces the neurons to secrete prostaglandins, which reset the hypothalamic thermostat at a higher temperature causing fever.

What are rigors and chills?

Rigors / chills: The skin gets cold and we start to shiver. It means that the core body temperature is rising.

What is the crisis?

This happens when a person gets warm and begins to sweat. It means that the core body temperature is falling.

What is the source of endogenous pyrogens?

Macrophages and other immunity cells.

How do Aspirin and Panadol (paracetamol) reduce fever?

Aspirin blocks the formation of prostaglandins.

Apart from infection, what other things can cause fever?

Viral causes, ovulation, excessive thyroid hormones, tumors, reactions with vaccines, tissue death (e.g. myocardial infarction), surgery, heat stroke.

What happens to thermoregulation in heat stroke?

Thermoregulation becomes erratic and impossible during a heat stroke because of the body’s inability to lose heat. Blood flow to skin is decreased, perspiration is greatly reduced and body temperature rises.

Why do febrile patients shiver (rigors)? Why do they sometimes sweat after a dose of Panadol or aspirin?

Patients shiver because their core body temperature is on the rise. They’re sweating after a dose of panadol because prostaglandin synthesis has ceased and they’re experiencing a crisis.

Once the set point is reset, how does the body increase its temperature to reach the new set point?

The body increases its Basal Metabolic Rate.

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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