Immune and Lymphatic System Flashcards

Vocabulary practice cards covering core terminology of the immune and lymphatic systems, white blood cell classifications, immunoglobulin function, immune acquisition types, stages of infection, and hypersensitivity reactions.

Innate Immunity

The body's non-specific first line of defense present at birth, consisting of physical barriers (skin, mucus membranes), chemical barriers (gastric juice, lysozymes), fever, inflammation, and fast-acting phagocytic cells.

Adaptive Immunity

A targeted and specific immune response involving B-lymphocytes and T-lymphocytes that develops over time, recognizes specific foreign antigens, and builds long-term immunological memory.

Hematopoietic Stem Cells (HSCs)

Stem cells located primarily in the bone marrow of adults (and prenatally in the yolk sac and liver) that produce all blood elements, including red blood cells, white blood cells, and platelets.

Lymphocytes

A specialized category of white blood cells originating in the bone marrow that account for approximately $30\%$ of circulating leukocytes and reside in lymphoid tissues to mediate adaptive immune responses.

Granulocytes vs. Agranulocytes

White blood cells categorized by cytoplasmic structure: granulocytes (neutrophils, eosinophils, basophils) contain visible granules for immediate response, whereas agranulocytes (lymphocytes, monocytes) lack visible granules and mediate long-term adaptive immunity.

Thymus

An endocrine and lymphoid organ located in the chest where immature T lymphocytes migrate from the bone marrow to undergo maturation.

Spleen

A major lymphoid organ that filters blood, removes abnormal blood cells via phagocytosis, recycles iron from worn-out erythrocytes, and initiates lymphocyte responses to blood-borne pathogens.

Lymph Nodes

Approximately $600$ small lymphoid organs clustered along lymphatic vessels—primarily in the neck, armpits, thorax, abdomen, and groin—that filter lymph fluid and house concentrated lymphocytes.

Peyer's Patches

Small aggregations of lymphatic tissue located throughout the ileum of the small intestine that monitor gut bacterial populations and prevent pathogenic growth.

Appendix

A small, blunt-ended tube of lymphatic tissue attached to the cecum of the large intestine that acts as a potential reservoir for beneficial gut bacteria.

Calor

One of the cardinal symptoms of inflammation, referring specifically to local heat resulting from increased vascular dilation and blood flow.

Helper T Cells (CD4+)

Lymphocytes that secrete cell-signaling proteins called cytokines and interleukins to activate, direct, and coordinate the actions of other immune cells, such as B cells and cytotoxic T cells.

Cytotoxic T Cells (CD8+)

Cell-mediated lymphocytes that directly target, attack, and kill foreign invaders, virus-infected host cells, and cancer cells.

B Cells

Bone marrow-derived lymphocytes that mediate antibody-mediated (humoral) immunity by recognizing free antigens and differentiating to secrete specific antibodies.

Natural Killer (NK) Cells

Specialized lymphocytes of the innate response that recognize and eliminate infected cells and cancerous cells early in disease progression without prior exposure.

Basophils

Granulocytes of innate immunity that promote inflammatory responses by releasing histamine, causing blood vessel dilation and increased capillary permeability.

Histamine

An inflammatory chemical mediator released by mast cells, basophils, and platelets that increases capillary permeability and vasodilates blood vessels.

Interferons

Proteins secreted by virus-infected leukocytes that defend uninfected cells by blocking cell-to-cell viral transmission.

5 Types of Antibodies

Y-shaped immunoglobulins (IgA, IgD, IgE, IgG, IgM) produced by B lymphocytes that specifically recognize, bind to, and tag pathogen antigens for destruction.

IgG

The main circulating antibody found in blood, lymph, and intestines that protects against bacteria, viruses, and toxins, and is the only immunoglobulin class able to cross the placenta.

IgA

An antibody secreted into body fluids such as sweat, tears, saliva, mucus, and colostrum that neutralizes and tags pathogens before they penetrate body tissues.

IgM

The initial antibody class secreted following primary antigen exposure; functions as a B-cell receptor, fixes complement, and includes anti-A and anti-B blood group agglutinins.

Types of Adaptive Immunity

The distinct mechanisms by which resistance is acquired: Natural Active (infection response), Artificial Active (vaccination), Natural Passive (maternal antibody transfer), and Artificial Passive (antibody infusion).

Natural Passive Immunity

Temporary immunity acquired by a fetus or infant through the natural transfer of maternal antibodies across the placenta or via colostrum in breast milk.

Artificial Active Immunity

Long-term immunity acquired through deliberate exposure to an antigen via vaccination, prompting the host to manufacture its own antibodies.

Stages of Infectious Disease

The four sequential periods of an infection: incubation period, prodromal stage, full stage of illness, and convalescent period.

Incubation Period

The time interval between initial pathogen entry into the host body and the first appearance of clinical signs or symptoms, during which pathogens replicate.

Prodromal Stage

The early phase of an infectious disease characterized by vague, non-specific general symptoms (such as fatigue or low-grade fever) during which the patient is most contagious.

Convalescent Period

The final stage of an infectious disease in which signs and symptoms diminish and disappear as the host recovers health.

Autoimmune Disease

A condition resulting from a breakdown in self-tolerance, wherein the immune system mistakenly targets and attacks self-antigens on healthy body tissues.

Type I Hypersensitivity

An immediate IgE-mediated allergic response causing rapid mast cell degranulation and histamine release upon exposure to an allergen.