Immunology Basics Quiz

Learning Objectives

• Students should be able to explain or identify terminologies in immunology, innate immunity components and reactions, adaptive immunity components and reactions, phagocytosis, molecular defenses, characteristics of inflammation, and the interferon and complement system.

Terminologies

• Immunity: An organism's ability to recognize and defend against infectious agents
• Susceptibility: Vulnerability to harm from infectious agents, the opposite of immunity
• Antigen: A foreign substance that induces an immune response, especially antibody production.
• Immune System: Composed of cells (chiefly lymphocytes) and organs (like the thymus) to provide specific immunity against infectious agents.

Differences Between Antigen and Antibody

• Antigen: A substance that stimulates an immune response, like a bacterial cell. It has epitopes (antigenic determinants).
• Antibody: The body's response to an antigen.

Types of Immunity

• Innate Immunity (Genetic): Genetically determined characteristics provide resistance to many infectious agents.
• Adaptive Immunity (Acquired): Immunity developed other than heredity. Naturally acquired through disease, artificially acquired through vaccines or immunizations.

Toxoids

• Toxoid is a normally toxic substance that has been treated to lose its toxicity yet maintains the ability to stimulate antibody production.
• Toxoids are components or toxins from pathogens and are used to immunize against diseases such as diphtheria, tetanus, and cholera.

Innate and Adaptive Immunity

• Adaptive Defenses: Target specific agents like viruses and bacteria.
• Innate Defenses: Respond to all types of invading agents.

Adaptive Immunity

• Responds to antigens by producing antibodies.
• Involves the activation of lymphocytes (specific immune system cells).
• Antibodies and cellular responses are more efficient against repeat infections.

Innate Immunity

• Physical barriers: Skin and mucus membranes protect against pathogens.
• Chemical barriers: Substances like sweat, sebum, and stomach acid create unfavorable conditions for pathogens.
• Cellular defenses: Cells in the body that engulf and destroy pathogens.
• Inflammation: Body's response to injury or infection characterized by redness, swelling, heat and pain.
• Fever: Body temperature rise to fight and inhibit pathogens.
• Molecular defenses: Proteins like interferons and complement, which destroy or block pathogens.

Physical Barriers

• Skin and mucous membranes protect internal body organs from injury and pathogens.
• Lining of the body surfaces that secrete chemicals, like human beta-defensin-2 on the skin.

Granulocytes

• Granulocytes are leukocytes with a lobed nucleus and granular cytoplasm.
• Basophils, mast cells, eosinophils and neutrophils (polymorphonuclear leukocytes) are types of granulocytes.

Agranulocytes

• Agranulocytes are leukocytes lacking granules.
• Monocytes and lymphocytes are examples.

Phagocytes

• Cells that engulf and destroy cellular debris, dead cells and pathogens.
• Macrophages are large phagocytes that can engulf larger particles.

Phagocytosis

• A process where phagocytes ingest microorganisms and debris.
• Steps involved: finding, adhering, ingesting and digesting the microorganisms.

Inflammation

• Inflammatory response: The body's defensive reaction to tissue damage caused by microbes.
• Characterized by redness, swelling, heat, pain, and possibly fever.

Molecular Defenses (Interferons and Complement)

• Interferons: Small proteins that inhibit viral replication and enhance other immune functions.
• Complement system: A group of proteins that enhance phagocytosis, kill pathogens directly, and promote inflammation.

Natural Killer Cells (NK Cells)

• Increase activity via exposure to interferons and cytokines.
• Recognize specific glycoproteins on infected cells and trigger their destruction.

Complement System

• Set of proteins that enhance immune responses, including phagocytosis and pathogen death.
• Works as a cascade, amplifying effects.

Opsonization

• Antibodies coat pathogens, improving phagocytosis efficiency.
• Complement components like C3b enhance phagocytosis.

Immune Cytolysis

• Complement system proteins can directly destroy cells, creating pores and disrupting cellular function (through membrane attack complexes).

Summary of Body's Non-Specific Defenses

• Physical Barriers: Prevent pathogen entry.
• Phagocytes: Eliminate pathogens and debris.
• Extracellular Killing: Destroy abnormal cells.
• Inflammatory Response: Local reaction to tissue damage.
• Fever: Body temperature rise.
• Interferons: Limit pathogen spread.
• Complement System: Enhances various immune functions.

Test your understanding of the key concepts in immunology, including innate and adaptive immunity, phagocytosis, and the immune response. This quiz will cover important terminologies and the functions of the immune system components. Enhance your knowledge of how the body defends against infectious agents.