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Ch 21 - Unit 4
Micro ch. 21
| Question | Answer |
|---|---|
| Respiratory tract | most common place for infectious agents to gain access to the body |
| Upper respiratory tract | mouth, nose, nasal cavity, sinuses, pharynx, epiglottis, larynx |
| Lower respiratory tract | trachea, bronchi, bronchioles, lungs, alveoli |
| Respiratory defenses | nasal hair, cilia, mucus, involuntary responses (coughing, sneezing, swallowing); macrophages, secretory IgA against specific pathogens; normal flora |
| Normal biota of respiratory tract | generally limited to upper tract; gram+ bacteria very common; disease causing bacteria present, can cause disease if host is immunocompromised |
| Upper Respiratory Tract Diseases Caused by Microorganisms | Rhinitis, Sinusitis, Acute Otitis Media, Pharyngitis, Diphtheria |
| Rhinitis or the Common Cold | caused by Rhinovirus, coronaviruses, adenoviruses (200 different kinds); Symptoms begin 2-3 days after infection sneezing, scratchy throat, runny nose (rhinorrhea); transmission via droplets |
| Sinusitis (sinus infection) | Generally follows bout of common cold; symptoms of nasal congestion, pressure above nose/in forehead, facial swelling and tenderness; discharge opaque w/ green yellow color in bacterial infection; allergy discharge is clear; fungal infections are rare |
| Otitis media (ear infection) | usually follows respiratory infection or rhinitis; caused by S. pneumoniae, Haemphilus influenzae; inflammation of the Eustachian tubes and buildup of fluid in the middle ear can lead to bacterial multiplication in the fluids |
| Chronic otitis media | when fluid remains in the middle ear for indefinite periods of time (may be caused by biofilm bacteria) |
| Pharyngitis | inflammation of the throat; reddened mucosa, swollen tonsils, sometimes white packets; incubation pd of 2-5 days; swelling may affect speech and swallowing |
| Strep throat/streptococcal pharyngitis | caused by S. pyogenes; Lancefield group A, beta hemolytic, bacitracin susceptible; diagnosed via throat cultures; latex agglutination detects antigens; beta lactam antibiotics |
| Complications of S. pyogenes | scarlet fever (systemic toxin); rheumatic fever (joint inflammation, heart valve damage); glomerulonephritis (kidney damage) |
| S. pyogenes virulence factors | surface antigens, toxins, enzymes; polysaccharides prevent digestion; spiky M protein prevents phagocytosis; capsule provides adherence; secretes streptolysins; erythrogenic toxin; some may act as superantigens |
| Diphtheria | caused by corynebacterium diphtheria; gram + bacillus; toxigenic disease; lysogenic beta phage; pseudo membrane, swelling can block airway; Symptoms initially in upper respiratory tract; Myocarditis can result; TDaP vaccine |
| Diphtheria toxin | A-B toxin (active domain and binding domain); B transports A into cell; A is an enzyme; translation inhibited, cells die; Toxoid vaccine |
| Whooping cough-pertussis | caused by bordatella pertussis; localized infection, toxin production, damage to cilia; Acellular vaccine prevention in TDaP immunization |
| Whooping cough stages | catarrhal and paroxysmal |
| Catarrhal whooping cough stage | after incubation from 3-21 days, bacteria in respiratory tract cause cold symptoms for 1 to 2 weeks |
| Paroxysmal stage of whooping cough | severe and uncontrollable coughing; violent coughing spasms can result in burst blood vessels in eyes, vomiting; followed by very long convalescent phase of weeks/months; other microorganisms can easily cause secondary infection |
| Respiratory Syncytial Virus (RSV) Infection | Produces giant multinucleated cells (syncytia) in the respiratory tract; most prevalent cause of respiratory infection in the newborn age group; more serious infections give rise to symptoms of croup (coughing, wheezing, dyspnea, rales) |
| Influenza (flu) | Begins in the upper respiratory tract; serious cases may also affect the lower respiratory tract; 1- to 4-day incubation period; Symptoms begin very quickly, extreme fatigue can last a few days or a few weeks |
| Influenza virus | Zoonosis; 3 viruses A, B, C; Birds are common reservoirs; enveloped RNA virus; Hemagglutinin (HA) and neuraminidase (NA) |
| Mechanisms of influenza variation | antigenic drift and antigenic shift |
| Antigenic drift | Mutation of genes; Altered binding by antibodies; Slower process |
| Antigenic shift | Gene reassortment; Coinfections; Rapid process |
| Tuberculosis | cause Mycobacterium tuberculosis; only about 5% of infected actually develop clinical case; untreated progresses slowly; clinically divided into primary tuberculosis, secondary tuberculosis, and disseminated tuberculosis |
| Primary tuberculosis | period of hidden infection; after 3-4 weeks, immune system mounts cell-mediated assault (large influx of mononuclear cells into lungs); Tubercles form, centers of tubercles break down into necrotic caseous lesions that calcify; Tuberculin reaction |
| Secondary (Reactivation) Tuberculosis | Live bacteria can remain dormant and become reactivated weeks, months, or years later |
| Chronic tuberculosis | tubercles filled with bacteria expand and drain into bronchial tubes and upper respiratory tract; severe symptoms such as violent coughing, greenish or bloody sputum, low-grade fever, anorexia, weight loss, extreme fatigue, night sweats, chest pain |
| Extrapulmonary Tuberculosis | Outside of the lungs; more common in immunosuppressed patients and young children; regional lymph nodes, kidneys, long bones, genital tract, brain, and meninges; complications are usually grave |
| Diagnosing TB | tuberculin skin test; chest x-ray; acid fast stain of sputum; vaccine adjuvants may give false positives |
| Pneumonia | Inflammatory condition of lungs; fluid fills alveoli; caused by variety of different microorganisms; viral usually milder than bacterial; begins w/ upper respiratory tract symptoms, followed by lung symptoms of chest pain, fever, cough, discolored sputum |
| Streptococcus pneumonia; “Pneumococcus” | alpha hemolytic streptococcus; most common cause of bacterial pneumonia; capsule is main virulence factor; pneumovax vaccine available |
| Legionella pneumophilia | Legionnaire’s disease; Philadelphia 1976; Found in water supplies, spread in aerosols; Intracellular parasite of phagocytes |
| Mycoplasma pneumonia | Walking pneumonias; most common cause; No cell wall – cells are variably-shaped |
| Histoplasmosis | caused by Histoplasma capsulatum; dimorphic fungus w/ worldwide distribution; common in Ohio River Valley; only about 1% infected become ill; normal soil bacteria, fertilized soil can instigate blooms which lead to outbreaks |
Created by:
michellerogers
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