Immune System Overview Quiz

Immune System Overview

• The immune system is a complex network of cells, tissues, and organs that combats disease and infection.
• It maintains a record of defeated microbes, enabling swift destruction if re-encountered.
• Key organs and tissues include tonsils, adenoids, lymph nodes, lymphatic vessels, thymus, spleen, appendix, bone marrow, and Peyer's patches.

Immune System Function

• Protects the body from diseases and foreign substances through white blood cells.
• Phagocytes destroy foreign cells, while lymphocytes provide learned immunity.
• The lymphatic system is crucial for fluid removal, fat absorption, and immune cell production.
• Removes excess fluids, proteins, and substances that leak from capillaries into tissues.
• Absorbs fatty acids and transports fat to the circulatory system.
• Produces immune cells (lymphocytes, monocytes, plasma cells).

Immune System Components

• Bone marrow produces white blood cells.
• Lymphoid tissues include the thymus, spleen, lymph nodes, tonsils, adenoids, and related tissues in the gastrointestinal, respiratory, and reproductive systems.

Lymphatic System Anatomy

• Lymphatic vessels, similar to veins, have valves that allow one-way flow and produce a beaded appearance.
• Lymphatic capillaries (terminal lymphatics) receive interstitial fluid, becoming lymph.
• Lymph travels through lymph nodes filtering out debris/pathogens.
• The body has about 500-600 lymph nodes, commonly found in groin, armpits, neck, chest, and abdomen.

Lymphocytes

• Key cells in adaptive immune responses.
• Different types include:
  • B lymphocytes: Generate antibodies.
  • T lymphocytes: Secrete chemical messengers.
  • Plasma cells: Secrete antibodies.
  • Natural killer (NK) cells: Destroy virally infected cells.

Lymphoid Organs

• Primary lymphoid organs (lymphocyte development):
  • Bone marrow: Oversees most hematopoietic functions.
  • Thymus: A bilobed organ positioned between the sternum and heart's aorta.
• Secondary lymphoid organs:
  • Lymph nodes: Filter lymph, removing debris and pathogens.
  • Spleen: Filters blood, removing microbes, and damaged red blood cells.
  • Tonsils: Located in the pharynx, help with immunity to oral pathogens.

Types of Immunity

• Innate/Genetic Immunity:
  • Present at birth, a nonspecific, initial defence.
  • Includes physical barriers (skin, mucous membranes, inflammation, phagocytosis), and chemical barriers (pH levels, enzymes, interferons, complement system, and natural killer lymphocytes).
• Acquired Immunity:
  • Develops throughout life, a specific response to pathogens.
  • Characterized by specificity, diversity, memory, and self/nonself recognition.
  • Two types of acquired immunity are humoral and cell-mediated immunity.