Study Guide Part 1: Chapter 20: The Lymphatic System and Immunity

Study Guide - Smart Notes

Tailored notes based on your materials, expanded with key definitions, examples, and context.

Chapter 20: The Lymphatic System and Immunity

Lymph Nodes and Disease Associations

Lymph nodes are small, bean-shaped structures that filter lymph fluid and are critical in immune surveillance. They are often associated with diseases such as breast cancer, where cancer cells may spread to nearby lymph nodes.

Lymph nodes trap pathogens and cancer cells, allowing immune cells to respond.
Breast cancer often spreads to axillary lymph nodes, which are checked during diagnosis and treatment.
Example: Sentinel lymph node biopsy is used to determine cancer spread.

Lymph Fluid Pathway and Structures

Lymph fluid travels through a network of vessels and nodes, ultimately returning to the bloodstream near the heart.

Lymphatic capillaries collect interstitial fluid.
Lymph vessels transport lymph through nodes for filtration.
Lymph ducts (thoracic duct and right lymphatic duct) return lymph to the subclavian veins near the heart.
Example: The thoracic duct drains lymph from most of the body.

Lacteal Location and Function

Lacteals are specialized lymphatic capillaries found in the villi of the small intestine.

Lacteals absorb dietary fats and transport them as chylomicrons.
Location: Within the intestinal villi.
Example: Fat absorption after a meal is facilitated by lacteals.

Immune Cells Monitoring for Cancer

Certain immune cells are responsible for detecting and destroying abnormal cells, including cancer cells.

Natural Killer (NK) cells monitor for cancer and infected cells.
Cytotoxic T cells also target and destroy cancerous cells.
Example: NK cells induce apoptosis in tumor cells.

MHC-1 and MHC-2 Binding with CD4 and CD8 Cells

Major Histocompatibility Complex (MHC) molecules present antigens to T cells, enabling immune recognition.

MHC-I binds to CD8+ cytotoxic T cells.
MHC-II binds to CD4+ helper T cells.
Example: Viral antigens are presented by MHC-I to CD8+ T cells.

Function of Cytotoxic T Cells

Cytotoxic T cells (CD8+) are essential for cell-mediated immunity.

Destroy infected or abnormal cells by releasing perforin and granzymes.
Induce apoptosis in target cells.
Example: Elimination of virus-infected cells.

Spleen: Purpose and Anatomical Location

The spleen is a lymphatic organ involved in filtering blood and mounting immune responses.

Location: Upper left quadrant of the abdomen, near the stomach.
Functions: Removes old red blood cells, stores platelets, and initiates immune responses to blood-borne antigens.
Example: The spleen responds to bacterial infections in the blood.

Thymus: Purpose and Anatomical Location

The thymus is a primary lymphoid organ where T cells mature.

Location: Superior to the heart, in the mediastinum.
Function: Site of T cell maturation and selection.
Example: The thymus is most active during childhood.

MALT: Purpose

Mucosa-Associated Lymphoid Tissue (MALT) protects mucosal surfaces throughout the body.

Includes: Tonsils, Peyer's patches, and appendix.
Function: Defends against pathogens entering via mucosal surfaces.
Example: Tonsils protect the pharynx from inhaled pathogens.

Interferon: Purpose

Interferons are proteins produced by cells in response to viral infections.

Function: Inhibit viral replication and activate immune cells.
Example: Interferon alpha is used therapeutically for viral infections.

Quantifying Immune Response

The process of measuring immune response is called titer determination.

Titer: Measures the concentration of antibodies in the blood.
Example: Vaccine efficacy is assessed by antibody titers.

Innate vs. Acquired/Adaptive Humoral Immunity

The immune system is divided into innate and adaptive components, with humoral immunity referring to antibody-mediated responses.

Innate immunity: Non-specific, immediate defense (e.g., barriers, phagocytes).
Adaptive (acquired) immunity: Specific, slower response; includes humoral immunity (B cells and antibodies).
Humoral immunity: Mediated by antibodies produced by B cells.
Example: Adaptive immunity develops after exposure to a pathogen.

Production of IgG, IgM, and IgE Antibodies

Different classes of antibodies are produced in response to various immune challenges.

IgM: First antibody produced during initial infection.
IgG: Most abundant; produced during secondary response and provides long-term immunity.
IgE: Produced in response to allergens and parasitic infections.
Example: IgE is elevated in allergic reactions.

Rheumatoid Arthritis: Disease Type

Rheumatoid arthritis is an autoimmune disease.

Autoimmune disease: The immune system attacks the body's own tissues.
Example: Joint inflammation and destruction in rheumatoid arthritis.

Process for Coating an Antigen

The process of coating an antigen with antibodies is called opsonization.

Opsonization: Enhances phagocytosis by marking antigens for destruction.
Example: Antibody-coated bacteria are more easily engulfed by phagocytes.

Newborn Protection from Antigens

Newborns are protected from antigens primarily through passive immunity.

Passive immunity: Transfer of antibodies from mother to child via placenta (IgG) and breast milk (IgA).
Example: Maternal IgG protects infants during early life.

Antibodies vs. Antibiotics

Antibodies and antibiotics are distinct in their origin and function.

Antibodies: Proteins produced by B cells to target specific antigens.
Antibiotics: Drugs that kill or inhibit the growth of bacteria.
Example: Penicillin is an antibiotic; IgG is an antibody.

Immune System Organs/Structures Associated with the Pharynx

Several lymphatic structures are located near the pharynx.

Tonsils: Pharyngeal, palatine, and lingual tonsils protect against inhaled or ingested pathogens.
MALT: Includes tonsils as part of mucosal immunity.
Example: Tonsillitis is inflammation of the tonsils.

Annual Vaccinations: Reasoning

Annual vaccinations are recommended to maintain immunity against evolving pathogens.

Pathogen mutation: Viruses like influenza change rapidly, requiring updated vaccines.
Immunity wanes: Antibody levels may decrease over time.
Example: Annual flu shots protect against new viral strains.

Summary Table: Immunity Types and Antibody Classes

Immunity Type	Key Features	Example
Innate Immunity	Non-specific, immediate, includes barriers and phagocytes	Skin, macrophages
Adaptive Immunity	Specific, slower, includes humoral and cell-mediated responses	Antibody production after vaccination
Antibody Class	When Produced	Function
IgM	First response to infection	Activates complement
IgG	Secondary response, long-term	Neutralizes toxins, opsonization
IgE	Allergic reactions, parasites	Triggers histamine release

Key Equations

Antibody Titer Calculation:

Additional info: Academic context was added to clarify immune cell functions, antibody classes, and the anatomical locations of lymphatic organs.