Overview
The lecture covers key concepts from Chapter 21 of Anatomy & Physiology, focusing on the lymphatic system and immunity.
Structure and Functions of the Lymphatic System
- The lymphatic system consists of lymph, lymphatic vessels, lymph nodes, tonsils, spleen, and thymus.
- Its main function is to return excess tissue fluid to the bloodstream and provide immune defense.
- Lymph is interstitial fluid that enters lymphatic vessels.
- Lymph nodes filter lymph and trap pathogens.
- The spleen filters blood, removes old red blood cells, and helps fight infection.
- The thymus is essential for T cell maturation, especially in childhood.
Immune System Components and Functions
- The immune system provides innate (nonspecific) and adaptive (specific) defense mechanisms.
- Innate immunity includes physical barriers (skin, mucous membranes), phagocytes, inflammation, fever, and natural killer cells.
- Adaptive immunity involves T cells (cell-mediated immunity) and B cells (antibody-mediated/humoral immunity).
- Antigens are substances that trigger an immune response.
- Antibodies are proteins produced by B cells to neutralize pathogens.
Immune Response Mechanisms
- Cell-mediated immunity uses T cells to attack infected cells directly.
- Humoral immunity relies on B cells becoming plasma cells that secrete antibodies.
- Primary immune response occurs on first exposure to an antigen and is slower.
- Secondary immune response is faster and stronger due to memory cells.
Disorders of the Lymphatic and Immune System
- Lymphedema is swelling due to lymphatic obstruction.
- Autoimmune diseases result when the immune system attacks the body's own tissues.
- Immunodeficiency is a weakened immune response; can be hereditary or acquired (e.g., HIV/AIDS).
- Allergies are exaggerated immune responses to harmless substances.
Key Terms & Definitions
- Lymph — clear fluid that circulates in lymphatic vessels, derived from interstitial fluid.
- Lymph node — small organ that filters lymph and houses lymphocytes.
- Antigen — foreign substance that induces an immune response.
- Antibody — protein produced by B cells that binds specific antigens.
- Innate immunity — nonspecific first-line defense against pathogens.
- Adaptive immunity — specific immune response involving lymphocytes.
Action Items / Next Steps
- Review textbook Chapter 21 for more detail on lymphatic organs and immunity.
- Study key terms and their functions for the upcoming quiz.
- Complete assigned reading on immune disorders.