Microbial Diseases of the Respiratory System – Vocabulary Review

Vocabulary flashcards covering structural anatomy, normal microbiota, and major bacterial, viral, and fungal diseases of the respiratory system, including causative agents, virulence factors, clinical stages, and prevention or treatment strategies.

Upper respiratory system

Anatomical region including the nose, pharynx, middle ear, and eustachian tubes.

Lower respiratory system

Composed of the larynx, trachea, bronchial tubes, and alveoli.

Ciliary escalator

Upward movement of mucus by ciliated epithelial cells that helps clear microbes from the lower respiratory tract.

Alveolar macrophages

Phagocytic cells that patrol alveoli and remove microorganisms and debris.

Normal respiratory microbiota

Resident microbes that inhibit pathogens by nutrient competition and production of inhibitory compounds; lower respiratory tract is nearly sterile.

Pharyngitis

Inflammation of the throat (sore throat); usually self-limiting.

Laryngitis

Inflammation of the larynx; affects voice production.

Tonsillitis

Inflammation of the tonsils; often accompanies pharyngitis.

Sinusitis

Inflammation of the sinus cavities; causes pressure and pain.

Epiglottitis

Life-threatening inflammation of the epiglottis in the upper respiratory system.

Streptococcal pharyngitis (strep throat)

Throat infection caused by group A β-hemolytic Streptococcus pyogenes.

Group A streptococci (GAS)

Serological group that includes Streptococcus pyogenes; major cause of strep throat.

Streptococcus pyogenes

Gram-positive cocci with capsule; produces streptokinases and streptolysins that damage tissues.

Streptolysins

Hemolytic toxins produced by S. pyogenes that lyse red and white blood cells.

Rapid antigen detection test

Diagnostic assay used to quickly identify group A streptococcal antigens in throat swabs.

Scarlet fever

Illness caused by erythrogenic toxin from lysogenized S. pyogenes, producing a red rash.

Erythrogenic toxin

Phage-encoded exotoxin causing the rash of scarlet fever.

Diphtheria

Respiratory disease characterized by a grayish throat membrane; caused by Corynebacterium diphtheriae.

Corynebacterium diphtheriae

Gram-positive pleomorphic rod that secretes diphtheria toxin.

Pseudomembrane (diphtheria)

Tough grayish membrane formed in the throat from dead cells and fibrin.

Diphtheria toxin

AB exotoxin that inhibits protein synthesis, damaging heart and kidneys.

DTaP vaccine

Combined vaccine containing diphtheria toxoid, tetanus toxoid, and acellular pertussis antigens.

Otitis media

Middle-ear infection characterized by pus behind the eardrum; common in children.

Streptococcus pneumoniae

Encapsulated Gram-positive diplococcus that can cause pneumonia and otitis media.

Haemophilus influenzae (nonencapsulated)

Gram-negative rod often involved in otitis media and other upper-respiratory infections.

Common cold

Mild viral infection of the upper respiratory tract causing sneezing, runny nose, and congestion.

Rhinovirus

Enterovirus responsible for 30–50% of common colds; grows best below core body temperature.

Betacoronavirus (common cold)

Coronavirus group causing ~10–15% of colds.

ICAM-1 receptor

Cell-surface molecule to which many rhinoviruses bind in the nasal cavity.

Canyon hypothesis

Model proposing that viral binding sites lie in surface depressions shielded from antibodies.

Bronchitis

Inflammation of the bronchi in the lower respiratory tract.

Bronchiolitis

Inflammation of the bronchioles; often affects infants.

Pneumonia

Infection in which pulmonary alveoli become inflamed and fluid-filled.

Pertussis (whooping cough)

Highly contagious respiratory illness caused by Bordetella pertussis.

Bordetella pertussis

Gram-negative coccobacillus that adheres to ciliated tracheal cells via a capsule.

Tracheal cytotoxin

Cell-wall fragment of B. pertussis that damages ciliated epithelial cells.

Pertussis toxin

Systemic exotoxin of B. pertussis causing lymphocytosis and other effects.

Catarrhal stage (pertussis)

Initial phase resembling a common cold; highly infectious.

Paroxysmal stage (pertussis)

Second phase with violent coughing fits and gasping (“whoop”).

Convalescence stage (pertussis)

Recovery phase; coughing gradually subsides over weeks to months.

Mycobacterium tuberculosis

Acid-fast, slow-growing rod that causes tuberculosis.

Caseous center

Cheesy necrotic core within a tubercle where M. tuberculosis can persist.

Ghon’s complexes

Calcified lesions of healed primary tuberculosis.

Miliary tuberculosis

Disseminated TB resulting from tubercle rupture and systemic spread.

Pneumococcal pneumonia

Lobar pneumonia caused by Streptococcus pneumoniae with high fever and chest pain.

Lyt A

Autolysin of S. pneumoniae contributing to release of inflammatory components.

Pneumolysin O

Pore-forming toxin of pneumococcus that is pro-inflammatory.

Conjugated pneumococcal vaccine

Vaccine covering 23 pneumococcal capsule types to prevent invasive disease.

Psittacosis (ornithosis)

Atypical pneumonia acquired from bird droppings; caused by Chlamydia psittaci.

Chlamydia psittaci

Obligate intracellular Gram-negative bacterium transmitted as elementary bodies.

Influenza virus

Enveloped virus with eight RNA segments causing the flu.

Hemagglutinin (HA) spikes

Surface glycoproteins that bind sialic acid receptors to initiate influenza infection.

Neuraminidase (NA) spikes

Influenza enzymes that cleave sialic acid, aiding viral release from host cells.

Influenza A virus

Influenza genus categorized by HA and NA variations; source of pandemics.

Antigenic drift

Gradual accumulation of mutations in HA/NA producing seasonal influenza variation.

Antigenic shift

Major genetic reassortment of influenza RNA segments producing new HA/NA combinations and pandemics.

SARS-CoV-2

Betacoronavirus responsible for COVID-19.

Spike (S) protein

Trimeric surface protein of SARS-CoV-2 that binds ACE2 receptors for entry.

Membrane (M) protein

Structural SARS-CoV-2 protein involved in viral assembly.

Envelope (E) protein

Small SARS-CoV-2 protein contributing to assembly and pathogenesis.

ACE2 receptor

Host cell receptor for SARS-CoV-2 spike protein; down-regulated after viral entry.

Antigenic drift (SARS-CoV-2)

High mutation rate of the RNA genome producing new viral variants.

Histoplasma capsulatum

Dimorphic fungus causing histoplasmosis; yeast form grows inside macrophages.

Dimorphic fungus

Fungus that exists as mold in the environment and yeast in host tissue.

Itraconazole

Azole antifungal drug used to treat histoplasmosis.

Pneumocystis jirovecii

Yeast-like fungus causing Pneumocystis pneumonia in immunocompromised patients.

Pneumocystis pneumonia (PCP)

Opportunistic lung infection; primary indicator disease for AIDS.

Trimethoprim-sulfamethoxazole

Combination antibiotic used to treat Pneumocystis pneumonia.