Physiology · MU Pleven

RESISTANCE OF THE BODY TO INFECTION. INNATE AND ACQUIRED IMMUNITY

Explains how neutrophils and macrophages attack invading microbes through chemotaxis, phagocytosis and successive lines of defence, then the feedback factors TNF, IL-1 and colony-stimulating factors. Also covers a comparison table of innate and acquired immunity, inflammation, the complement cascade, antigen presentation via MHC classes I and II, T-cell roles, and the primary and secondary B-cell responses with antibodies.

Inside: 1 section · 2 labelled pictures · 1 table · 25 flashcards · 6 min

Topic 16 of 17 in the MU Pleven syllabus for Physiology (Medicine, Year 2). The free AceMed note covers it in 1 section, about 903 words (6 min of reading), with 25 flashcards.

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  1. RESISTANCE OF THE BODY TO INFECTION. INNATE AND ACQUIRED IMMUNITY

RESISTANCE OF THE BODY TO INFECTION. INNATE AND ACQUIRED IMMUNITY

It is mainly the neutrophils and monocytes that attack and destroy invading bacteria, viruses, and other injurious agents.

-Both the neutrophils and macrophages move through the tissues via ameboid motion when stimulated by products formed in inflamed areas.

-This attraction of the neutrophils and macrophages to the inflamed area is called chemotaxis.

-One of the Most Important Functions of the Neutrophils and Macrophages Is Phagocytosis.

-The Tissue Macrophage Is the First Line of Defense against Invading Organisms.

-Neutrophil Invasion of the Inflamed Tissue Is a Second Line of Defense.

-A Second Macrophage Invasion of the Inflamed Tissue Is the Third Line of Defense.

-The Fourth Line of Defense is the Greatly Increased Production of Both Granulocytes and Monocytes by Bone Marrow.

Many Factors Are Involved in the Feedback Control of the Macrophage and Neutrophil Response.

  1. 1. Tumor necrosis factor (TNF)
  2. 2. Interleukin-1 (IL-1)
  3. 3. Granulocyte-monocyte colony-stimulating factor (GM-CSF)
  4. 4. Granulocyte colony-stimulating factor (G-CSF)
  5. 5. Monocyte colony-stimulating factor (M-CSF)

These five factors are formed by activated macrophages and T cells in the inflamed tissues. The main instruments of the increased production of granulocytes and monocytes by bone marrow are the three colony stimulating factors; the combination of TNF, IL-1, and colony-stimulating factors provides a powerful feedback mechanism that begins with tissue inflammation and proceeds to the formation of defensive white blood cells and removal of the cause as well as the inflammation.

Innate and acquired immunity:

Inflammation:

  • Inflammation is one of the first responses of the immune system to infection or irritation.
  • It is stimulated by chemical factors released by injured cells and serves to establish a physical barrier against the spread of infection, and to promote healing of any damaged tissue following the clearance of pathogens.

Inflammatory response is characterized by the following symptoms: Redness, heat, swelling, loss of function of inflamed and pain.

Compliment system:

  • The complement system is a biochemical cascade of the immune system that helps, or “complements”, the ability of antibodies to clear pathogens or mark them for destruction by other cells.
  • The cascade is composed of many plasma proteins, synthesised in the liver, primarily by hepatocytes.
  • The proteins work together to: trigger the recruitment of inflammatory cells "tag" pathogens for destruction by other cells by opsonizing, or coating, the surface of the pathogen form holes in the plasma membrane of the pathogen, resulting in cytolysis of the pathogen cell, causing the death of the pathogen.

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