Innate & Adaptive Immunity, Vaccines, and Lymphatic System – Key Vocabulary

Vocabulary flashcards covering innate and adaptive immunity, fever, vaccines, lymphatic structures, and related concepts from the BNNS502 worksheets.

First Line of Defence

Innate, non-specific barriers (skin, mucous membranes, secretions) that prevent entry of a wide variety of microorganisms.

Second Line of Defence

Innate, non-specific internal responses such as phagocytosis, inflammation, fever, and antimicrobial substances that act after pathogens penetrate barriers.

Third Line of Defence

Adaptive, specific immunity that eliminates particular microbes and provides memory for faster future responses.

Inflammation – Purpose

Destroys microbes, prevents their spread, clears debris, and initiates tissue repair.

Fever – Role

Systemic rise in body temperature that slows pathogen growth, speeds body reactions, removes free iron, and induces rest.

Fever – Complications

May cause tachycardia, acidosis, dehydration/electrolyte imbalance, febrile convulsions, delirium, coma, or death >44-46 °C.

Interferons

Antiviral proteins released by infected cells that hinder viral replication in neighboring cells.

Iron-Binding Proteins

Molecules such as transferrin that sequester iron, limiting bacterial growth.

Complement Proteins

Plasma proteins that enhance phagocytosis, inflammation, and directly lyse microbes.

Antimicrobial Proteins (AMPs)

Short peptides that insert into microbial membranes to impede growth.

Naturally Acquired Active Immunity

Immunity gained after natural exposure to antigens; body makes its own antibodies and memory cells.

Naturally Acquired Passive Immunity

Short-term immunity from maternal antibodies transferred via placenta or breast milk.

Artificially Acquired Active Immunity

Immunity produced after vaccination; body generates antibodies and memory cells.

Artificially Acquired Passive Immunity

Immediate, short-term protection from injection of preformed antibodies (immunoglobulins).

Passive Immunity – Disadvantage

Provides no immunological memory; protection is temporary and does not guard against future exposures.

Live Attenuated Vaccine

Contains weakened microbes that replicate mildly, eliciting strong, long-lasting immune responses (e.g., MMR).

Killed (Inactivated) Vaccine

Contains whole microbes that are dead; cannot replicate but still provoke immunity (e.g., cholera, typhoid).

Subunit/Portion Vaccine

Uses only parts of a pathogen (protein or polysaccharide); safer but less immunogenic (e.g., Hepatitis B).

Toxoid Vaccine

Contains inactivated toxins to stimulate antitoxin antibody production (e.g., tetanus, diphtheria).

Most Effective Vaccine Type

Live attenuated vaccines—produce robust antibody and cellular responses with long-lasting immunity.

Live Vaccine – Disadvantages

Tiny risk of reversion to virulence and higher chance of transient disease signs and symptoms.

Other Vaccine Types – Limitation

Inactivated, subunit, and toxoid vaccines usually induce weaker immunity, often requiring booster doses.

Herd Immunity

Community protection that arises when a high proportion of individuals are immune, reducing disease transmission.

Herd Immunity – Risk of Non-Vaccination

Lower vaccination rates increase susceptible hosts, raising outbreak likelihood for the whole population.

Age-Related Immune Change

Older adults produce fewer antibodies, resulting in slower responses to infection and vaccines.

Lymphatic System – Fluid Balance

Drains excess interstitial fluid and returns it to the bloodstream.

Lymphatic System – Lipid Transport

Carries dietary lipids and fat-soluble vitamins from intestinal villi to blood.

Lymphatic System – Immune Function

Monitors lymph for pathogens and destroys microbes or abnormal cells.

Major Lymph Node Clusters

Cervical (neck), axillary (armpit), and inguinal (groin) regions.

Infected Lymph Node Features

Enlarged, soft, very tender, and movable on palpation.

Cancerous Lymph Node Features

Enlarged, firm, non-tender, and fixed to underlying structures.

B Cells

Lymphocytes that differentiate into plasma cells producing antibodies and memory B cells.

T Cells

Lymphocytes that destroy infected or cancerous body cells and regulate immune responses.

Macrophages (in Lymph Nodes)

Phagocytic cells that ingest and digest foreign substances.

Spleen – Location

Left hypochondriac region between the stomach and diaphragm.

Spleen – Functions

Removes damaged blood cells, stores platelets, produces blood cells in fetus, and performs immune surveillance.

Spread of Infection via Lymphatics

Pathogens or cancer cells may overwhelm nodes, travel in lymph, and establish secondary infections or tumors.