Untitled Quiz

Inflammation

• Inflammation is a protective response intended to eliminate the cause of cell injury, infectious agents, and necrotic cells, and to initiate repair.
• Components of inflammation include blood vessels, white blood cells and platelets, plasma proteins and chemical mediators (coagulation/fibrinolytic system, kinin system, complement system), and extracellular matrix and stromal cells (structural fibrous proteins, adhesive glycoproteins, proteoglycans, basement membrane).
• The immune response plays a crucial role in inflammation, with macrophages functioning in the elimination of microbes and dead tissue, along with mediators like cytokines and nitric oxide.

Components of Acute Inflammation

• Vascular Changes: Alterations in blood vessel caliber lead to vasodilation and increased blood flow. Changes in vasculature also permit plasma proteins to leave circulation (increased permeability).

• Cellular Events: Leukocytes emigrate from the microcirculation and accumulate in the focus of injury.

Increased Vascular Permeability

• Leads to protein-rich fluid and cells entering extravascular tissues.
• Increases osmotic pressure, causing more fluid to flow out of the blood into tissues, producing edema.

Edema

• Transudate: Mechanism: hydrostatic pressure imbalance across vascular endothelium; fluid content is low in protein (ultrafiltrate of blood plasma). Typical in noninflammatory conditions.
• Exudate: Mechanism: alteration in normal permeability of small blood vessels in area of injury; fluid content is high in protein. Typical in inflammatory conditions.

Types of Inflammation

• Acute Inflammation: Fast onset (minutes to hours), short duration (minutes to days), characterized by mainly neutrophils, usually mild and self-limiting tissue injury, and fibrosis.

• Chronic Inflammation: Slow onset (days to years), long duration, with infiltrates of monocytes/macrophages and lymphocytes, often severe and progressive tissue injury and fibrosis.

External Manifestations of Acute Inflammation

• Heat
• Redness
• Swelling
• Pain
• Loss of function

Systemic Effects of Inflammation

• Fever (elevated body temperature)
• Elevated plasma levels of acute phase proteins
• Increased white blood cell count (leukocytosis)
• Increased heart rate
• High blood pressure
• Decreased sweating
• Rigors/shivering
• Chills (perception of cold)
• Malaise
• Anorexia

Stimuli for Acute Inflammation

• Infections (bacteria, fungi, viruses, parasites)
• Trauma (various chemical and physical agents - heat, cold, burns, radiation)
• Chemicals (acids, alkalis, bacterial toxins, metals)
• Tissue necrosis
• Foreign bodies
• Immunologic reactions

Morphological Patterns of Acute Inflammation

• Serous: Exudation of cell-poor fluid into spaces created by injury to surface epithelia or into body cavities (e.g., skin blisters).

• Fibrinous: Consequence of more severe injuries, resulting in greater vascular permeability that allows large molecules (such as fibrinogen) to pass the endothelium.

• Suppurative (Purulent): Collection of large amounts of pus (an exudate consisting of many neutrophils, debris of necrotic cells, and edema fluid).

• Ulcer: Local defect of the surface of an organ or tissue that is produced by sloughing (shedding) of inflamed necrotic tissue.

Outcomes of Acute Inflammation

• Complete resolution
• Healing by connective tissue (scarring or fibrosis)
• Progression to chronic inflammation

Chronic Inflammation

• Inflammation of prolonged duration (weeks to years)
• Characterized by infiltration with mononuclear cells (macrophages, lymphocytes, plasma cells), tissue destruction, and repair.

Immune Components of inflammation

• Macrophages: Dominant cells of chronic inflammation, involved in phagocytosis.
• B and T Lymphocytes: Important in cell-mediated immunity.
• Mast cells: Source of histamine in allergic reactions.

Tissue Repair

• Regeneration: Replacement of damaged cells by similar parenchymal cells, returning to a normal state. Typical in rapidly dividing epithelia (skin, intestines). Requires intact connective tissue.

• Scar Formation: Occurs when tissues are incapable of regeneration or supporting structures are severely damaged. Connective tissue is laid down.

Immunity

• The immune system protects against microorganisms and removes damaged/cancerous cells.
• Innate immunity: immediate, nonspecific protection (skin, mucous membranes).
• Adaptive immunity: takes 7-10 days to develop, specific to the antigen (cellular or humoral).
• T-cells: destroy antigen.
• B-cells: produce antibodies.

Altered Immune Responses

• Hypersensitivity: Inappropriate immune response to an antigen, leading to inflammation and destruction of healthy tissue. This includes four subtypes: type I (IgE-mediated), type II (cytotoxic), type III (immune complex-mediated), and type IV (cell-mediated).
• Autoimmune disorders: Normal defenses recognize self as foreign, leading to destruction of the body's own tissues. Examples: systemic lupus erythematosus, rheumatoid arthritis.
• Immunodeficiency: Diminished or absent immune response, increasing susceptibility to infections. Can be primary (genetic defect) or secondary (underlying disease, malnutrition, drugs).