Embriología y anatomía del pulmón

EMBRIOLOGY OF THE LUNG

• The lungs develop from the ventral wall of the foregut (endoderm).
• Embryonic period stages: pseudoglandular, canalicular, saccular, alveolar.
• Fetal period stages: surfactant begins around weeks 26-28.
• The respiratory diverticulum gives rise to the lungs.
• Key structures develop at different stages of gestation.

ANATOMY OF THE LUNG

• Lungs have 3 lobes (right) and 2 lobes (left).
• The conducting zone includes the trachea, bronchi, and bronchioles.
• The trachea and bronchi transport air.
• Bronchioles are the final part of the conducting zone.
• Respiratory zone is where gas exchange occurs (alveolar ducts and sacs).

HISTOLOGY OF THE LUNG

• Clara cells increase towards terminal bronchioles, have secretory function.
• Type I pneumocytes (95%): flattened, thin structure.
• Type II pneumocytes (5%): produce surfactant (reduces surface tension of alveoli).
• Alveoli provide large surface area for gas exchange.
• Surfactant is crucial for preventing lung collapse.

CONGENITAL ANOMALIES

• Pulmonary Hypoplasia: Defective development of lungs, resulting in decreased weight and volume & abnormalities.
• Cystic Fibrosis: Autosomal recessive disorder affecting multiple organs, especially the lungs. Involves thick, sticky mucus buildup. Causes sinusitis and wide airways in the lungs.

ATELECTASIS

• Atelectasis is the collapse of the lung.
• Types of atelectasis: Resorption (airway obstruction), Compression (fluid buildup), Contraction (pulmonary or pleural fibrosis).

RESPIRATORY DISTRESS SYNDROME OF THE NEWBORN

• Surfactant deficiency: is the leading cause of RDS in premature babies.
• Surfactant lowers surface tension, preventing alveolar collapse.
• Insufficient surfactant leads to lung immaturity.
• Risk factors include premature birth, diabetes, and C-section.

OBSTRUCTIVE AND RESTRICTIVE PULMONARY DISEASES

• Obstructive diseases: Characterized by airflow limitation.
• Restrictive diseases: Characterized by reduced lung expansion.
• Examples of causes: ARDS, pneumoconiosis, chest wall disorders.
• Key tests include FEV1, which evaluates airflow obstruction.

CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD)

• COPD: Progressive lung disease characterized by chronic bronchitis and emphysema; often coexisting.
• Emphysema: Destruction of the alveolar walls, leading to air trapping and decreased elasticity.
• Chronic bronchitis: Inflammation of the large airways with increased mucus production resulting in chronic cough and excessive sputum production.
• Symptoms: dyspnea (shortness of breath), chronic cough, sputum production.
• Major risk factor: cigarette smoking

CHRONIC BRONCHITIS

• Chronic inflammation of the bronchi.
• Recurrent infections play a role
• Hypersecretion of mucus.
• Reid index (ratio of mucous gland thickness to bronchial wall thickness), increased in bronchitis.

EMPHYSEMA

• Destruction of alveolar walls, reduced lung elasticity.
• Dyspnea, usually chronic progressive, and typically irreversible.
• The major symptom is shortness of breath.
• Most often caused by cigarette smoking.
• Categorized as: centriacinar, panacinar, or paraseptal.

BLUE BLOWER vs. PINK PUFFER

• Differences are clinical presentation and symptoms associated with chronic bronchitis: overweight, cyanotic, increased hemoglobin.
• Differences are clinical presentation and symptoms associated with emphysema: thin, pink, dyspnea.

MORPHOLOGICAL TYPES OF EMPHYSEMA

• Centriacinar: Begins around respiratory bronchioles.
• Panacinar: Destroys the entire alveoli uniformly.
• Paraseptal: Localized around the pleura, commonly in lower lobes.

PNEUMOCONIOSIS

• Conditions caused by inhaling mineral dusts or organic dusts.
• Coal dust, silica, asbestos, etc.
• Respiratory illnesses that develop due to prolonged exposure to a certain particulates.

ANTHRACOSIS

• Lung condition resulting from carbon particle inhalation.
• Usually benign and does not cause significant disease, but can cause progressive fibrosis with severe exposure.

ASBESTOSIS

• A group of lung diseases caused by inhaling asbestos fibers.
• Asbestos related conditions: asbestosis, lung cancer, mesothelioma, etc.
• Symptoms include shortness of breath, cough, chest pain, etc.

SILICOSIS

• Progressive interstitial lung disease caused by silica inhalation.
• Symptoms, include dyspnea, cough, and possible lung cancer.

HYPERSENSITIVITY PNEUMONITIS

• Inflammatory lung disease, arising from exposure to specific antigens.
• Often associated with an agricultural or occupational setting.

SARCOIDOSIS

• Multisystemic disease of unknown cause, typically involving the lungs.
• It's characterized by the formation of noncaseating granulomas in the affected organs.
• No specific treatment.

USUAL INTERSTITIAL PNEUMONIA (UIP) / IDIOPATHIC PULMONARY FIBROSIS (IPF)

• Chronic progressive lung fibrosis of unknown etiology.
• No known cure.

CRYPTOGENIC ORGANIZING PNEUMONIA (BOOP)

• Characterized by an inflammatory reaction in the lung, resulting in abnormal tissue growth filling alveoli and airways.
• It typically responds well to corticosteroid treatment.

ACUTE RESPIRATORY DISTRESS SYNDROME (ARDS)

• Caused from a variety of factors including infection, injuries, etc.
• Characterized by acute lung inflammation with fluid buildup.

BRONCHIECTASIS

• Permanent dilatation of bronchi and bronchioles, typically caused by recurrent inflammation and infection
• Can be congenital or acquired.

COMMUNITY-ACQUIRED PNEUMONIA (CAP)

• Infection of the lungs, acquired from the community.
• This can be bacterial or viral

PNEUMOCYSTIS JIROVECII PNEUMONIA

• Opportunistic infection, prevalent in immunocompromised individuals.
• Characteristics: pink, foamy material in the alveoli, and presence of cup-shaped cysts.

CYTOMEGALOVIRUS (CMV) PNEUMONIA

• Viral infection, can lead to lung damage in immunocompromised individuals.
• Characterized by hemorrhagic nodules of the lung and also present in the blood vessel walls .

ASPERGILLUS

• Invasive fungal infection, especially individuals receiving immunosuppressive drugs.

TUBERCULOSIS

• Bacterial infection of the lungs, spread by airborne droplets.
• Can be dormant for years.

DISEASES OF VASCULAR ORIGIN

• Pulmonary Embolism: Blood clot obstructing a pulmonary artery.
• Pulmonary Hypertension: Elevated pulmonary artery pressure.
• Important to note the high morbidity potentially to both conditions.
• Diffuse Pulmonary Hemorrhage Syndromes: Conditions leading to diffuse bleeding in the lungs

Este cuestionario cubre la embriología, anatomía y la histología del pulmón. Abarca desde el desarrollo embrionario hasta las estructuras que facilitan el intercambio de gases. Ideal para estudiantes de ciencias de la salud y biología.