Chapter 16: Diseases of the Respiratory System

This set covers viral, bacterial, fungal, and parasitic diseases of the respiratory system, including their causative agents, clinical stages, and diagnostic characteristics based on the lecture notes.

Mucociliary escalator

A protective mechanism in the trachea and bronchi that removes inhaled transient microbes; it is notably inhibited by cigarette smoking.

Pharyngitis

Commonly known as a sore throat, this is an infection of the pharynx that can be viral or bacterial in origin.

Laryngitis

An infection of the larynx that frequently results in the loss of voice.

Epiglottitis

An infection of the epiglottis that can lead to airway closure and suffocation; historically caused by $Haemophilus influenza$, but now more commonly viral due to immunization.

Croup

A viral infection in children involving the larynx and epiglottis, characterized by difficult breathing and a high-pitched barking cough.

Stridor

A high-pitched, noisy respiration sound indicative of progression in parainfluenza or croup infections.

Streptococcus pyogenes

The group A $\beta$-hemolytic bacterium responsible for strep throat, affecting primarily children aged 5 to 15.

Rheumatic fever

A complication that occurs in 3% of untreated strep throat cases when $S. pyogenes$ interacts with the immune system.

Glomerulonephritis

Kidney damage or failure that can result from an untreated infection of $Streptococcus pyogenes$.

Sinusitis

Infection of the sinus cavities; categorized as acute (less than one month) or chronic (over 3 months).

Diphtheria

A disease caused by toxigenic strains of $Corynebacterium diphtheriae$ which interferes with protein synthesis, particularly affecting the heart and kidneys.

Pseudomembrane

A formation of damaged epithelial cells, fibrin, and blood cells in the pharynx that can block the airway in diphtheria patients.

Rhinoviruses

A primary cause of the common cold that replicates best at $33^{\circ} C$ to $34^{\circ} C$ and is inactivated by acidic conditions.

MERS (Middle Eastern Respiratory Syndrome)

A coronavirus infection with a 60% death rate, associated with camels and bats, characterized by symptoms similar to SARS plus kidney failure.

HPIV-1 and HPIV-2

The specific types of human parainfluenza viruses that are the most common causes of croup in children.

Respiratory syncytial virus (RSV)

An enveloped RNA virus from the Paramyxoviridae family that is a significant cause of lower respiratory infections like pneumonia.

2009 H1N1

A quadruplet reassortment influenza virus containing genes from North American swine and avian flu, human flu, and Eurasian swine flu.

Bordetella pertussis

The aerobic, encapsulated, Gram-negative coccobacillus responsible for whooping cough.

Catarrhal stage

The initial stage of pertussis (7 to 10 days post-exposure) featuring fever, sneezing, vomiting, and a mild dry cough.

Paroxysmal stage

The second stage of pertussis involving violent coughing sieges, ropelike mucus, and potential cyanosis.

Cyanosis

A bluing of the skin caused by a lack of oxygen in the blood, often occurring during severe pertussis coughing fits.

Classic Pneumonia

Inflammation of lung tissue that causes more deaths in the U.S. than any other infectious disease.

Mycobacterium tuberculosis

The slow-growing bacterium that causes tuberculosis by multiplying inside phagocytic white blood cells.

Tubercles

Chronic granulomas in the lungs consisting of macrophages, giant cells, and connective tissue, which can permanently destroy lung function.

Caseous necrosis

The cheesy appearance of the central portion of a tubercle as it undergoes tissue destruction.

Miliary tuberculosis

A condition where tuberculosis organisms spread via the circulatory system to other organs, such as the spine or urogenital tract.

PPD skin test

A diagnostic test involving the intracutaneous injection of purified protein derivative to detect a delayed hypersensitivity reaction to TB.

Aspergillosis

Also known as farmer's lung disease, caused by $Aspergillus fumigatus$; it can lead to the formation of 'fungus balls' in the lungs.

Paragonimus westermani

A parasitic lung fluke acquired by ingesting infected shellfish, which matures in the bronchioles and causes chronic cough.