physiology of the immune system L12pt4

Types of Immunity

• Two major types: Innate (nonspecific) and Adaptive (specific) immunity.
• Both systems work together and depend on each other.

Innate Immunity

• General protection everyone is born with; first line of defense.
• Includes external barriers: skin, mucous membranes (nose, throat, gastrointestinal tract).
• Protects by preventing pathogen entry; akin to a castle moat.
• If barriers are breached (e.g., cuts), the body heals and mobilizes defenses.
• Key components:
  • Phagocytes: Dispose of pathogens; types include neutrophils and macrophages.
  • Phagocytosis: Process of engulfing pathogens ("phago"=to eat, "cyto"=cell, "osis"=condition).
  • Inflammation: The body's response to injury/infection, characterized by redness, heat, swelling, pain; aids tissue repair.
  • Fever: Systemic response to infection, beneficial in moderate amounts; helps sequester iron and zinc, speeds tissue repair.

Adaptive Immunity

• Also known as acquired immunity; develops over time with exposure to pathogens or vaccination.
• Involves lymphocytes: B lymphocytes (B cells) and T lymphocytes (T cells).
  • B Lymphocytes: Mature in red bone marrow and are involved in humoral (antibody-mediated) immunity.
  • Produce antibodies secreted in body fluids.
  • T Lymphocytes: Mature in thymus; involved in cellular (cell-mediated) immunity.
• Adaptive immunity creates memory for identified threats, granting lifelong immunity against many diseases.