Inflammatory Response

Inflammatory Response (Acute and Chronic Inflammation) and Wound Healing

Inflammatory Response

Definition of Inflammation

  • Inflammation: An automatic response to cell injury, intended to remove the causative organism, dead cells, or tissue.

    • Categories of Inflammation:

    • A. Acute Inflammation

    • B. Chronic Inflammation

Acute Inflammation

Characteristics

  • Early Response to Injury: Occurs promptly after injury to tissues.

  • Phases of Acute Inflammation:

    1. Vascular Phase

    2. Cellular Phase

  • Cell Types Involved: Primarily white blood cells (leukocytes).

  • Local Manifestation: Presence of exudates (fluids that leak out of blood vessels).

Vascular Phase of Acute Inflammation

  • Key Events:

    • Vasoconstriction: Initial narrowing of blood vessels to minimize blood loss.

    • Vasodilation: Following vasoconstriction, there is an increase in blood flow, leading to:

    • Redness and warmth in the affected area.

    • Increased permeability of capillaries, allowing fluids (exudates) to escape into surrounding tissues.

  • Mediators: Chemical substances such as

    • Histamine

    • Nitric Oxide

  • Effects: Resulting in swelling (edema), pain, and impaired function due to the accumulation of fluid and immune cells.

Cellular Phase of Acute Inflammation

  • Key Processes:

    • Entry of White Blood Cells:

    • Destruction of Infective Organisms: White blood cells, including neutrophils and later macrophages, migrate to sites of infection.

    • Removal of Damaged Cells: Cellular debris is phagocytosed.

    • Release of More Inflammatory Mediators: Sustains the inflammatory response and aids in tissue repair.

Overview of Acute Inflammation

  • **Pathogens invade tissues, leading to cellular injury, which activates:

    • Molecules in plasma

    • Mast cells

    • Macrophages**

  • Response Sequence:

    • Vasodilation leads to increased blood flow.

    • Increased capillary permeability allows antibodies and phagocytes to pass into the inflamed area.

    • Clinical Manifestations:

    • Redness

    • Increased temperature

    • Edema (swelling)

    • Pain

    • Increased phagocytosis

    • Release of pro-inflammatory cytokines such as Tumor Necrosis Factor (TNF) and Interleukin-1 (IL-1) leads to potential systemic responses like fever.

Exudates in Acute Inflammation

  • Types of Exudates:

    • Serous: Clear, yellowish fluid.

    • Hemorrhagic: Blood-stained fluid.

    • Fibrinous: Thick, gel-like fluid due to high fibrin content.

    • Membranous: Pseudomembrane formation.

    • Purulent: Pus-filled, indicating the presence of infection.

Chemical Mediators of Inflammation

  • Key Mediators:

    • Bradykinin: Involved in pain and vasodilation.

    • Complement Proteins: Enhances inflammatory processes and opsonization.

    • Histamine: Triggers vasodilation and increased permeability of blood vessels.

    • Prostaglandins: Mediators of inflammation, pain, and fever.

    • Leukotrienes: Promotes bronchoconstriction and vascular permeability.

    • Cytokines: Proteins important for cell signaling in the immune system.

    • Chemokines: Direct the movement of immune cells.

    • Nitric Oxide: Vasodilator, playing a role in the immune response.

Pyrexia (Fever)

What Causes a Fever?

  • Pyrogens: Substances that induce fever, can be endogenous or exogenous.

  • Types of Fever:

    • Neurogenic Fever: Caused by damage to the hypothalamus.

    • Intermittent Fever: Fever that returns to normal between episodes.

    • Remittent Fever: Fever that does not return to normal but fluctuates.

    • Sustained Fever: Continuous fever with little fluctuation.

    • Recurrent Fever: Recurrent episodes of fever interspersed with periods of normal temperature.

Intermittent Fever Display

  • Graph illustrating temperature fluctuations highlighting peaks and troughs for different types of fever (e.g., intermittent, remittent, sustained).

Manifestations of Inflammatory Response

  • Common Symptoms:

    • Anorexia: Loss of appetite.

    • Myalgia: Muscle pain.

    • Arthralgia: Joint pain.

    • Fatigue: General feeling of tiredness.

    • Dehydration: Due to increased metabolic demands.

    • Tachycardia: Elevated heart rate.

    • Increased Respiratory Rate: To compensate for metabolic changes.

    • Increased Metabolic Rate: Elevation due to inflammation.

    • Headache: Often associated with fever.

    • Herpetic Lesions: Skin manifestations related to viral infections.

    • Delirium: Severe confusion or disorientation due to systemic effects of inflammation.

Fever Treatment

  • Strategies:

    • Determining the underlying cause of the fever and addressing it directly.

    • Mechanisms to decrease body temperature, such as using cooling mattresses and cooling blankets.

    • Nutrient Replacement: To support metabolic needs during fever.

    • Antipyretic Drugs: Medications to reduce fever (e.g., ibuprofen, acetaminophen).

Tissue Repair and Wound Healing

Types of Repair

  • Tissue Regeneration: Restoration of tissue to its original state.

  • Scar Tissue Formation: Replacement of lost tissue with fibrotic scar tissue.

Stages of Wound Healing

  1. Inflammatory Phase: Immediate response, characterized by hemostasis and inflammatory processes.

  2. Proliferative Phase: Tissue formation and closure of the wound.

  3. Remodeling Phase: Maturation and reorganization of the newly formed tissue.

Phases of Wound Healing

  • Primary Intention: Wound edges are brought together, leading to minimal scarring (e.g., surgical wounds without tissue loss).

  • Secondary Intention: Wound healing process in cases of significant tissue loss, usually requiring more extensive granulation and scar formation.