9.2.3 Inflammatory Response

The inflammatory response is a major component of the non-specific defence. Any damage to tissue, whether caused by an infectious microorganism or by physical injury, even just a scratch or an insect bite triggers this response. Inflammation can be localized or systemic (widespread). Local inflammation is an inflammatory response confined to a specific area of the body. The classical signs of inflammation are heat, pain, redness, swelling, and loss of function.

Definition

Inflammatory Response: The inflammatory response is a major component of the non-specific defence. Any damage to tissue triggers this response. Inflammation can be localized or systemic.

Local Inflammation: Local inflammation is an inflammatory response confined to a specific area of the body.

Main Idea

• The inflammatory response is a major component of the non-specific defence.
• Any damage to tissue triggers this response.
• Damage can be caused by an infectious microorganism or by physical injury.
• Even just a scratch or an insect bite triggers this response.
• Inflammation can be localized or systemic.
• Local inflammation is confined to a specific area.
• Classical signs of inflammation:

Core Concept

• Inflammatory response = major component of non-specific defence
• Trigger = tissue damage
• Types = localized or systemic
• Local inflammation = confined to a specific area
• Signs = heat, pain, redness, swelling, loss of function
• Chemical alarm signals = histamine
• Histamine = induces vasodilation and leakiness
• Function = eliminate cause of injury; clear necrotic cells; initiate tissue repair; prevent spread of infection

Detailed Explanation

Inflammatory Response

• The inflammatory response is a major component of the non-specific defence.
• Any damage to tissue, whether caused by an infectious microorganism or by physical injury, even just a scratch or an insect bite triggers this response.
• Inflammation can be localized or systemic (widespread).
• Local inflammation is an inflammatory response confined to a specific area of the body.
• The classical signs of inflammation are heat, pain, redness, swelling, and loss of function.

Chain of Events

The figure 9.10 shows the chain of events that make up the inflammatory response, in case where a pin has pricked the skin and infected it with bacteria.

• The first thing that happened when a tissue is injured is that the damaged cells release chemical alarm signals such as histamine.
• The chemical sparks the mobilization of various defence.
• Histamine for instance induces neighbouring blood vessels to dilate and blood vessels start leaking.
• Blood supply to the damaged area increases, and blood plasma passes out of the leaky vessels into the interstitial fluid of the affected tissues causing inflammation.

Function of Inflammation

• Eliminate the initial cause of cell injury.
• Clear out necrotic cells and tissues damaged from the original insult.
• Initiate tissue repair.
• Prevent the spread of infection to the surrounding tissues.

Summary Table of Inflammatory Response

Summary of Chain of Events

Intermediate Level

Inflammatory Response

Chain of Events

Functions of Inflammation

Formula / Mathematical Form

Not applicable to this topic.

Solved Example

Not applicable to this topic (descriptive topic).

Important Points

• 1. Inflammatory response is a major component of non-specific defence.
• 2. Any damage to tissue triggers this response.
• 3. Damage can be caused by infectious microorganisms.
• 4. Damage can be caused by physical injury.
• 5. Even a scratch or insect bite triggers this response.
• 6. Inflammation can be localized or systemic.
• 7. Local inflammation is confined to a specific area.
• 8. Classical signs: heat, pain, redness, swelling, loss of function.
• 9. Damaged cells release histamine.
• 10. Histamine induces vasodilation.
• 11. Blood vessels start leaking.
• 12. Blood supply to damaged area increases.
• 13. Blood plasma passes into interstitial fluid.
• 14. Inflammation occurs.
• 15. Phagocytes migrate to the area.
• 16. Phagocytes consume bacteria and cell debris.
• 17. Tissue heals.
• 18. Inflammation eliminates the initial cause of cell injury.
• 19. Inflammation clears necrotic cells and tissues.
• 20. Inflammation initiates tissue repair.

Remember

• - Inflammatory response = major component of non-specific defence
• - Trigger = tissue damage
• - Types = localized or systemic
• - Local inflammation = confined to a specific area
• - Signs = heat, pain, redness, swelling, loss of function
• - Chemical alarm signals = histamine
• - Histamine = induces vasodilation and leakiness
• - Function = eliminate cause of injury; clear necrotic cells; initiate tissue repair; prevent spread of infection

Common Mistakes

• 1. Confusing inflammation and infection — Inflammation is a response; infection is caused by microbes.
• 2. Mixing up the signs — Heat, pain, redness, swelling, loss of function.
• 3. Forgetting the role of histamine — Released by damaged cells.
• 4. Mixing up the effects of histamine — Vasodilation and leakiness.
• 5. Believing inflammation is always bad — It is a necessary defence mechanism.
• 6. Mixing up local and systemic inflammation — Local = confined; systemic = widespread.
• 7. Forgetting the role of phagocytes — Consume bacteria and cell debris.
• 8. Mixing up the functions — Eliminate cause; clear necrotic cells; initiate repair; prevent spread.
• 9. Thinking inflammation is not important — It is a major component of non-specific defence.
• 10. Mixing up the chain of events — Injury, histamine, vasodilation, phagocytes, healing.

Quick Revision

The inflammatory response is a major component of the non-specific defence. Any damage to tissue, whether caused by an infectious microorganism or by physical injury, even just a scratch or an insect bite triggers this response. Inflammation can be localized or systemic (widespread). Local inflammation is an inflammatory response confined to a specific area of the body. The classical signs of inflammation are heat, pain, redness, swelling, and loss of function. The figure 9.10 shows the chain of events that make up the inflammatory response, in case where a pin has pricked the skin and infected it with bacteria. The first thing that happened when a tissue is injured is that the damaged cells release chemical alarm signals such as histamine. The chemical sparks the mobilization of various defence. Histamine for instance induces neighbouring blood vessels to dilate and blood vessels start leaking. Blood supply to the damaged area increases, and blood plasma passes out of the leaky vessels into the interstitial fluid of the affected tissues causing inflammation. The function of inflammation is to eliminate the initial cause of cell injury, clear out necrotic cells and tissues damaged from the original insult and the inflammatory process, and to initiate tissue repair. The inflammatory response also helps to prevent the spread of infection to the surrounding tissues.

60-Second Revision

• Inflammatory response = major component of non-specific defence
• Trigger = tissue damage
• Types = localized or systemic
• Local inflammation = confined to a specific area
• Signs = heat, pain, redness, swelling, loss of function
• Chemical alarm signals = histamine
• Histamine = induces vasodilation and leakiness
• Function = eliminate cause of injury; clear necrotic cells; initiate tissue repair; prevent spread of infection
• Warning: Inflammation is a necessary defence mechanism; it is not the same as infection

NEXT TOPIC

• Chapter:
• 9. Immunity

• Topic:
• 9.2.4 TEMPERATURE RESPONSE

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