Lymphatic System and Immunity: Key Terms and Concepts

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Lymphatic System and Immunity

Introduction

The lymphatic system is a crucial part of the human body's defense mechanisms, working alongside the immune system to protect against pathogens and maintain fluid balance. This study guide covers essential terms, structures, and processes related to lymphatic and immune function, as presented in the provided questions.

Key Terms and Definitions

Immunoglobulins: Also known as antibodies, these are proteins produced by plasma cells that bind to specific antigens to neutralize or mark them for destruction.
Chemotaxis: The movement of cells (such as phagocytes) toward chemical signals, often released at sites of infection or inflammation.
Wandering Macrophage: A type of phagocytic cell that moves through tissues to engulf pathogens and debris.
Acquired Active Immunity: Immunity developed after exposure to an antigen, either through infection or vaccination.
Lymph Nodes: Small, bean-shaped structures that filter lymph and house immune cells.
Opsonization: The process by which antibodies or complement proteins coat a pathogen, enhancing its uptake by phagocytes.
Spleen: An organ that filters blood, removes old red blood cells, and helps mount immune responses.
MALT (Mucosa-Associated Lymphoid Tissue): Lymphoid tissue found in mucous membranes throughout the body, providing immune protection at entry points.
Cisterna Chyli: A dilated sac at the lower end of the thoracic duct that collects lymph from the lower limbs and intestines.
Lymphedema: Swelling caused by abnormal accumulation of lymph fluid, often due to obstruction of lymphatic vessels.
Humoral Immunity: Immunity mediated by antibodies produced by B cells.
Edema: General term for swelling due to excess fluid in tissues.
Red Bone Marrow: Site of hematopoiesis, where blood cells, including lymphocytes, are produced.
Thymus: Organ where T lymphocytes mature.
Type II Alveolar Cells: Cells in the lungs that produce surfactant to prevent alveolar collapse.

Processes and Structures

Phagocytosis: The process by which certain cells engulf and digest pathogens and debris.
Monocyte Migration: Monocytes leave the blood, enter tissues, and differentiate into macrophages.
Antibody Action: Antibodies bind to microbes, making them more susceptible to phagocytosis (opsonization).
Interstitial Fluid Accumulation: When filtration exceeds reabsorption, fluid accumulates in tissues, leading to edema.
Adaptive Immunity: Immunity that involves specific responses to antigens, primarily through B and T lymphocytes.
Plasma Cells: Differentiated B cells that secrete antibodies in response to antigen exposure.
Antigen Presentation: Immune cells process and present antigens to T cells to initiate adaptive responses.
Lymph: Fluid found within lymphatic vessels, similar to interstitial fluid, that transports immune cells and waste products.
Surfactant Production: Type II alveolar cells produce surfactant, reducing surface tension and preventing lung collapse.
Antibacterial Agents: Tears, saliva, and other secretions contain lysozyme, an enzyme that destroys pathogens.
Mucous Membranes: Specialized lymph tissue (MALT) protects mucosal surfaces from infection.
Thoracic Duct: The main lymphatic vessel that drains lymph into the left subclavian vein.
Lymphatic Vessels: Filtered by lymph nodes, these vessels transport lymph throughout the body.

Table: Comparison of Key Lymphatic Structures

Structure	Main Function	Location
Lymph Node	Filters lymph, houses immune cells	Along lymphatic vessels
Spleen	Filters blood, immune response	Upper left abdomen
Thymus	T cell maturation	Anterior mediastinum
MALT	Protects mucosal surfaces	Respiratory, digestive, urinary tracts
Cisterna Chyli	Collects lymph from lower body	Base of thoracic duct

Formulas and Equations

Starling's Law of Capillaries: Describes fluid movement across capillary membranes. Where: = net fluid movement = filtration coefficient = capillary hydrostatic pressure = interstitial hydrostatic pressure = reflection coefficient = capillary oncotic pressure = interstitial oncotic pressure

Examples and Applications

Example: Swelling in the legs due to blocked lymphatic vessels is called lymphedema.
Application: Vaccines stimulate acquired active immunity by introducing antigens to the body.

Additional info: Some definitions and explanations have been expanded for clarity and completeness.