Chapter 19 - Infectious Diseases Affecting the Respiratory Systems

upper respiratory tract

Includes nose, pharynx, middle ear, and eustachian tubes.

lower respiratory tract

Includes trachea, bronchial tubes, and alveoli.

nasal hair

Traps large particles entering the nasal cavity.

ciliary escalator

Cilia move mucus and trapped particles upward toward the throat.

mucus

Sticky secretion that traps microbes.

Secretory IgA

Antibody found in mucosal secretions that neutralizes pathogens.

Alveolar Macrophages

Immune cells in the lungs that engulf pathogens.

Streptococcus pyogenes

Gram-positive bacterium causing strep throat and scarlet fever.

Pharyngitis

Inflammation of the pharynx; sore throat.

Scarlet Fever

Illness caused by erythrogenic toxin from S. pyogenes; rash and red tongue.

Rhinitis 

Common cold; viral infection of nasal passages.

Sinusitis

Inflammation of the sinuses; caused by viruses, bacteria, or fungi.

Otitis Media

Middle ear infection; common in children.

Pneumonia

Infection of the alveoli; fluid accumulation impairs gas exchange.

Lobar Pneumonia

Pneumonia affecting one or more lobes of the lungs.

Bronchopneumonia

Pneumonia affecting alveoli near bronchi.

Pleurisy

Inflammation of the pleural membranes.

SARS-CoV-2

Coronavirus causing COVID-19; RNA virus with spike proteins.

COVID-19

Viral pneumonia; may affect multiple organs.

Streptococcus pneumoniae

Gram-positive diplococcus; causes pneumococcal pneumonia.

Legionella

Gram-negative rod; causes Legionnaires’ disease via aerosol transmission.

Mycoplasma pneumoniae

No cell wall; causes walking pneumonia

Pneumocytis jirovecii

Fungus causing pneumonia in immunocompromised individuals.

VAP (Ventilator-Associated Pneumonia)

Pneumonia linked to mechanical ventilation.

MRSA

Methicillin-resistant Staphylococcus aureus; common cause of VAP.

Influenza Virus 

RNA virus with HA and NA spikes; causes flu.

Hemagglutinin (HA)

Viral spike protein that binds to host cells.

Neuraminidase (NA)

Viral spike protein that helps virus exit host cells.

Antigenic Drift

Minor changes in HA/NA; allows immune evasion.

Antigenic ShiftGram-negative coccobacillus; causes whooping cough.

Major changes in HA/NA; leads to pandemics.

Bordetella pertussis 

Gram-negative coccobacillus; causes whooping cough.

Pertussis Toxin

Enters bloodstream; contributes to symptoms.

Tracheal Toxin

Damages ciliated cells in the trachea.

DTaP Vaccine

Prevents diphtheria, tetanus, and pertussis.

RSV (Respiratory Syncytial Virus)

Common viral infection in infants; causes syncytia.

Mycobacterium tuberculosis 

Acid-fast rod; causes TB; slow-growing and resistant.

Tubercle

Walled-off lesion in lungs containing TB bacteria.

Caseous Center

Necrotic center of a tubercle; cheese-like appearance.

Miliary Tuberculosis

Disseminated TB infection throughout the body.

Tuberculin Skin Test

Diagnostic test for TB exposure.

MDR/XDR TB

Multi-drug/extensively drug-resistant tuberculosis strains.

BCG Vaccine

TB vaccine derived from M. bovis; not widely used in the U.S.