Lecture 13 Flashcards
Respiratory System Function
Respiratory system oxygenates blood and removes carbon dioxide
Circulatory System Function
Circulatory system transports gases in the bloodstream
How many lobes are each lung composed of?
The right lung has 3 and the left lung has 2
Bronchi
Largest conducting tube
Bronchioles
Less than 1 mm (thin system of tubes that help conduct air into and out of the lungs)
Terminal bronchioles
Located at the terminus of the conducting zone (last of the conducting airflow in lungs)
Respiratory bronchioles
Distal to terminal bronchiole with alveoli projecting from walls
Alveoli
O2 and CO2 exchange (type
I pneumocytes) have cells that produce surfactant (type II pneumocytes)
Pulmonary Surfactant
Produced by type II pneumocytes. Reduces surface tension in the alveoli
Acinus or respiratory unit
Functional unit of lung (alveoli)
Ventilation
Movement of air into and out of lungs (inspiration and expiration, respectively)
Inspiration
Caused by the action of the diaphragm (descends) and intercostal muscles (expand)
Where does gas exchange occur?
Gas exchange occurs between alveolar air and pulmonary capillaries
What is Atmospheric pressure at sea level?
760 mm Hg
Partial pressure
Part of the total atmospheric pressure exerted by a gas
Partial pressure of oxygen (PO2)
0.20x760mmHg=152mmHg
Why do gases diffuse among blood, tissues, and pulmonary alveoli?
Differences in their partial pressure
Requirements for efficient gas exchange
Changes in atmospheric O2 or CO2, Large capillary surface area in contact with the alveolar membrane, Unimpeded diffusion across the alveolar membrane, Normal pulmonary blood flow, and Normal pulmonary alveoli (Impairment of any will result in impaired gas exchange)
Pleura
Thin membrane covering lungs (visceral pleura) and internal surface of the chest wall (parietal pleura)
Pleural cavity
Potential space between lungs and chest wall
Intrapleural pressure
Pressure within pleural cavity (normally less than intrapulmonary pressure), also referred to as negative or subatmospheric pressure
What does the release of the vacuum in pleural space lead to?
Lung Collapse (loss of negative pressure)
What can impair lung function when found inside the pleural space?
Fluid (inflammatory or hemothorax) or air accumulation (pneumothorax)
Pulmonary Function Tests
Tested by measuring volume of air that can be moved into and out of lungs under normal conditions
Vital capacity
Maximum volume of air expelled after maximum inspiration – can be used to evaluate progress of chronic disease (emphysema)
One-second forced expiratory volume (FEV1)
Maximum volume of air expelled in 1 second – can be used to detect airway narrowing in inflammatory or bronchospasm (Asthma)
Pulse oximeter
Measures oxygen saturation in blood
Pneumothorax
Escape of air into pleural space due to lung injury or disease (Loss of negative pressure)
Manifestations of Pneumthorax
Chest pain, shortness of breath, reduced breath sounds on the affected side, chest x-ray: lung collapse and air in the pleural cavity
Tension pneumothorax
Positive pressure develops in the pleural cavity, and air flows through the perforation into the pleural cavity (air flows on inspiration but cannot escape on expiration which causes a build-up of pressure)
Tension Pneumothorax treatment
Chest tube is inserted into pleural cavity, left in place until lung heals/re-expands
Atelectasis
Collapse of the lung due to obstructive atelectasis or compression atelectasis
Obstructive atelectasis
Thick mucus secretions, tumors, foreign object, diaphragm elevates on affected side
Compression atelectasis
From external compression of the lung by fluid, air or blood in the pleural cavity, and reduced lung volume and expansion
Pneumonia
Inflammation of the lung (when exudate reaches the pleural surface), Exudate spreads through the lung, Exudate fills alveoli, Affected lung portion becomes relatively solid (consolidation)
Classification of Pneumonia
Etiology (cause), anatomic distribution of inflammatory process, and predisposing factors
Most common cause of Pneumonia
Streptococcus pneumoniae infection
Lobar
Infection of one or more lobes of lung from bacterial pnemonia
Bronchopneumonia
Infection of parts of lobes or lobules adjacent to
bronchi by pathogenic bacteria
Interstitial or primary atypical pneumonia
Caused by virus or Mycoplasma
Post-op pneumonia
Accumulation of mucus secretions in bronchi
Aspiration pneumonia
Irritating substance, foreign body, food, vomit, water inhaled
Obstructive pneumonia
Distal to bronchial narrowing
Clinical features of pneumonia
Fever, cough, purulent sputum, pain on respiration (if pleura involved), shortness of breath, impaired blood oxygenation, lung consolidation, and elevated WBC
SARS (severe acute respiratory syndrome)
Highly communicable lower pulmonary infection, Unusual coronavirus first identified in late 2002, last in 2004
SARS Manifestations
Fever, chills, mild respiratory infection, occasional diarrhea, acute respiratory distress 3-7 days from onset
Middle eastern respiratory syndrome (MERS-CoV)
First identified in 2012, Infections still occurring – relatively low numbers (2500 total as of Jan 2021 – only 45 cases in 2020), Similar symptoms to SARS, but much more deadly than SARS (35% fatality), Small, isolated outbreaks
COVID-10 (SARS CoV2)
Genetically similar to SARS Cov1 (83%) with extensive protein homology, Over 200 million cases confirmed with over 4 million deaths, Most (80%) develop mild symptoms, 5% critical and require ventilation support
Pneumocystis Pneumonia cause
Pneumocystis jiroveci, protozoan parasite of low pathogenicity, Organisms attack and injure alveolar lining, leading to exudation of protein material into alveoli
Who does Pneumocystis Pneumonia affect?
Affects mainly immunocompromised persons (AIDS patients, patients receiving immunosuppressive drugs, premature infants)
Pneumocystis Pneumonia symptoms and diagnosis
Thick mucous/sputum too thick to expel creates – non- productive cough, dyspnea, pulmonary consolidation. Diagnosis through lung biopsy, bronchoscopy or from bronchial secretions
Usual Interstitial Pneumonia
Injury to connective tissue causing fibrosis which tends to be viral or genetic (autoimmune) in origin. Marked by patchy collagen distribution scarring and fibroblast proliferation (slow gradual progress over a period of years)
Tuberculosis (TB)
Infection from acid-fast bacterium, Mycobacterium tuberculosis transmitted from airborne droplets (Infection begins in lungs but can spread to other parts of the body)
Mycobacterium tuberculosis
Causes TB; Bacterium has a capsule composed of waxes and fatty substances; resistant to destruction (hard to stain)
Granuloma
Aggregation of immune cells with central necrosis, indicates development of cell-mediated immunity (TB) - formed as immune cells to attack TB
Multinucleated giant cells
Bacteria plus fused macrophages and periphery of lymphocytes and plasma cells
Caseous Granuloma
Fibrous tissue surrounding central cluster of macrophages/giant cells, center region becomes necrotic as granulomatous inflammation progresses – highly characteristic of TB infection
Miliary tuberculosis
Systemic spread of TB (blood/lymph), Large numbers of organisms disseminated in body when a mass of tuberculous inflammatory tissue erodes into a large blood vessel (AIDS patients and immunocompromised individuals are at risk)
Diagnosis of Miliary TB
Skin test, detects immune reaction to TB proteins
(Mantoux test) – can detect latent, Chest X-ray, Sputum culture
Drug-Resistant Tuberculosis
Resistant strains of organisms emerge with failure to complete treatment or premature cessation of treatment (Multi-drug resistant TB (resistant to at least two of the anti-TB drugs) and Extensively drug-resistant TB (no longer controlled by many antituberculosis drugs))
Treatment for Drug-Resistant Tuberculosis
Tx- combination drug regimen for several months (6-9 months)
Acute bronchitis
Inflammation of the tracheobronchial mucosa (sore throat common in URTI)
Chronic bronchitis
From chronic irritation of respiratory mucosa by smoking or atmospheric pollution
Bronchiectasis
Walls thickened and weakened by chronic inflammation become saclike and fusiform (chronic cough, purulent sputum, and repeated pulmonary infection)
Bronchitis and Bronchiectasis treatment
Exercise, oxygen therapy, drugs can provide symptom relief, Only effective treatment is surgical resection of affected segments of lung
Chronic Obstructive Pulmonary Disease (COPD) anatomic derangements
Inflammation and narrowing of terminal bronchioles, Dilation and coalescence of pulmonary air spaces, Loss of lung elasticity; lungs no longer recoil normally following inspiration (caused by chronic irritation: Smoking and inhalation of injurious agents)
Pulmonary emphysema
Destruction of fine alveolar structure
of lungs with formation of large cystic
spaces which begins in upper lobes and eventually affects all lobes
Chronic bronchitis
Chronic inflammation of terminal bronchioles; cough plus purulent sputum
COPD Pathogenesis
Chronic Inflammatory swelling of mucosa, leukocytes accumulate in bronchioles and alveoli, releasing proteolytic enzymes that attack elastic fibers of lung’s structural support, coughing, retention of secretions predisposes to pulmonary infection and impairs gas exchange, Increased susceptibility to respiratory infections
COPD Treatment
Tx: Promote drainage of bronchial secretions to decrease frequency of pulmonary infections, Bronchodilators, inhaled steroids, oxygen therapy, lung therapy/exercise – lung transplant
Antitrypsin
Alpha1 globulin; prevents lung damage from lysosomal enzymes (trypsin, fibrinolysin, thrombin) – produced by liver, monocytes (protects lungs from the collateral damage of neutrophils)
Alpha1-Antitrypsin Deficiency
Deficiency permits enzymes to damage lung tissue, Autosomal dominant (1 mutation milder form of disease compared to double mutation), prone to emphysema development if levels are low, tends to affect lower lobes, causes an absent cough and excessive sputum production, and digestion of connective tissue
Bronchial Asthma
Spasmodic contraction of smooth wall muscles of bronchi and bronchioles and increased bronchial mucous secretions in response to stimuli, Attacks are often precipitated by allergens: Inhalation of dust, pollens, animal dander, other allergens (Atopy) – type 1 hypersensitivity + stress, exercise, cold, smoke, pollutants and respiratory infection
Bronchial Asthma onset
Child - typically allergic asthma, Adult - occupational/environmental
Bronchial Asthma Treatment
Fast acting bronchodilators (Ventolin), long-acting bronchodilators, Long- acting drugs that reduce the reactivity of airways and block release of mediators from mast cells (Corticosteroids, anti-leukotrienes)
Neonatal Respiratory Distress Syndrome
Progressive respiratory distress soon after birth, inadequate surfactant in lungs which causes alveoli to not expand normally during inspiration and collapse during expiration (most common in premature infants, infants delivered by cesarean section, and infants born to diabetic mothers)
Neonatal Respiratory Distress Syndrome treatment
Adrenal corticosteroids to mother before delivery and Oxygen and surfactant (delivered by ET tube)
Adult Respiratory Distress Syndrome
Shock (traumatic or septic) is a major manifestation that causes damage (fall in BP and reduced blood flow to lungs)
Treatment of Adult Respiratory Distress Syndrome
treat condition that caused shock (infection etc.), oxygen ventilator with slightly increased pressure (aids in diffusion) - High mortality rate 30-40% due to COVID-19
Pulmonary Fibrosis
Fibrous thickening of alveolar septa from irritant gases, organic and inorganic particles, inflammation, repair post ARDS which makes lungs rigid causing impaired diffusion of gases
Pneumoconiosis
Lung injury from inhalation of injurious dust or other particulate material (Silicosis, asbestosis (can also cause cancer), cotton fibers, coal dust)
Vaping (E-cigarette) Induced Lung Injury
Acute severe respiratory distress after vaping: SOB, chest pain – in some cases leading to development of chronic lung disease (syndrome is called EVALI) - similar damages to ARDS (This illness only occurred for a short period of time and mainly in the states)
Lung Carcinoma
Usually smoking-related neoplasm, Common malignant tumor in both men and women who smoke, lung cancer kills more women then breast cancer
Lung Carcinoma Classification, Prognosis, and Treatment
Classification (Squamous cell carcinoma and Adenocarcinoma - common, Large and small cell carcinoma (poor prognosis)
Prognosis (depends on stage, age, histology, health, biomarkers, generally poor)
Treatment (Surgery, radiation and chemotherapy for small cell carcinoma and advanced tumors, treatments with specific blocking agents)
