Respiratory System Anatomy and Function Quiz

Respiratory System Anatomy and Function

• The respiratory system is divided into the upper and lower respiratory tracts, with the upper tract including the nasal cavity, paranasal sinuses, nasopharynx, and larynx, while the lower tract consists of the trachea, bronchi, bronchioles, and alveoli.
• The nasal cavity has a respiratory region with pseudostratified ciliated columnar epithelium, mucous and serous glands, and an olfactory region with bipolar neurons and sustentacular cells for olfaction.
• The paranasal sinuses are lined by respiratory epithelium and provide increased surface for humidification of air, but can also be a location of infections.
• The nasopharynx is lined by respiratory epithelium and contains large masses of lymphoid tissue, providing immune surveillance at the portals of entry of the respiratory and gastrointestinal systems.
• The larynx, which connects the pharynx to the trachea, is lined by a combination of respiratory epithelium and non-keratinized stratified squamous epithelium, and contains vocal cords that vibrate as air passes between them to make sound.
• The trachea, the beginning of the lower respiratory tract, is a continuously open, flexible tube of hyaline cartilage and fibroelastic tissue, with C-shaped rings of hyaline cartilage and bands of smooth muscle.
• The pulmonary components of the mononuclear phagocyte system include alveolar macrophages, which are located in alveoli and phagocytose and remove unwanted material from air spaces, and pulmonary interstitial macrophages, which are stationary in the connective tissue between alveoli.
• The pulmonary blood vessels consist of pulmonary arteries that carry de-oxygenated blood from the right heart and give rise to alveolar capillaries involved in gas exchange, and bronchial arteries that supply thick-walled structures in the lung with oxygenated blood.
• The pulmonary connective tissue contains reticulin, collagen, and elastin fibers, with a large amount of elastin in the alveolar walls, which is condensed at the opening of alveoli to form a supporting ring.
• The pleura, which lines the lung and pleural cavities, consists of a thin flattened mesothelium supported by fibroelastic connective tissue, with the visceral pleura covering the lungs and the parietal pleura lining the thoracic wall.
• The respiratory system is involved in two interrelated processes: cellular respiration, which involves the biochemical processes that generate energy, and mechanical respiration, which moves air and allows for gas exchange through inhalation, gas exchange, and exhalation.
• Key resources for understanding the respiratory system anatomy and function include "Robbins Basic Pathology", "Pathologic Basis of Veterinary Disease", and "Wheater’s Functional Histology: A

Respiratory Tract Anatomy and Histology

• Trachea is lined by respiratory epithelium, composed of pseudostratified columnar ciliated cells and goblet cells containing mucigen granules
• Submucosa of the trachea contains seromucous glands, with a decrease in number in lower parts of the trachea
• Bronchi branch off from the trachea and undergo changes in diameter, cell height, goblet cell concentration, smooth muscle, cartilage, and submucosal glands as they progress into the lung
• Bronchioles are airways with a diameter of less than 1 mm, lacking cartilage and submucosal glands, and are lined by simple ciliated columnar to cuboidal epithelium
• Clara cells are present in terminal and respiratory bronchioles, functioning in surfactant production and as stem cells
• Neuroendocrine cells in bronchioles contain peptide hormones that regulate smooth muscle tone
• Terminal bronchioles lead to respiratory bronchioles, which are interrupted by alveoli in their walls, marking the beginning of the gas exchange portion
• Alveoli are lined by type I and II pneumocytes, with type II pneumocytes producing surfactant and functioning as stem cells
• Type I pneumocytes form the majority of the alveolar surface and constitute the gas diffusion barrier
• Type II pneumocytes secrete surfactant to prevent alveolar collapse and are abundant in granular eosinophilic cytoplasm containing lamellar bodies
• The air-blood barrier consists of attenuated cytoplasm of type I pneumocytes, fused basement membrane, and thin cytoplasm of capillary endothelial cells
• The pulmonary mononuclear phagocyte system includes alveolar macrophages and pulmonary interstitial macrophages, which phagocytose and remove unwanted material from the air spaces

Bronchopneumonia and Interstitial Pneumonia in Animals

• Bronchopneumonia in animals refers to an inflammatory process in the bronchial, bronchiolar, and alveolar lumens leading to consolidation, often caused by viruses, bacteria, and mycoplasmas.
• The most common type of pneumonia in domestic animals is bronchopneumonia, characterized by cranioventral lung consolidation.
• Cranioventral pneumonia in animals is due to the gravity effect, as this portion is reached more quickly during breathing.
• Fibrinous bronchopneumonia in animals is characterized by fibrinous coating within 24-48 hours and affects the cranioventral portion of the lungs.
• Pneumonic Mannheimiosis in animals results in necrotic interlobular septal areas, fibrin coating, and coagulative necrosis, with congested vessels and hemorrhages.
• Atypical pneumonia in animals may not appear severe in X-rays but can have severe symptoms, often due to Mycoplasma pneumoniae and other intracellular bacteria or viruses.
• Interstitial pneumonia in animals involves inflammation localized to the alveolar walls and can be caused by aerogenous or hematogenous agents.
• Aerogenous agents for interstitial pneumonia in animals include inhaled toxic gases or pneumotropic viruses, while hematogenous agents include bacterial toxins or endotheliotropic viruses.
• Acute interstitial pneumonia in animals includes neutrophil infiltration of alveolar interstitium, while chronic interstitial pneumonia involves fibrosis of alveolar walls and proliferation of type II pneumocytes.
• Interstitial pneumonia in animals can result in edematous lungs with thickened interstitial and prominent costal imprints.
• The text provides detailed pathological descriptions and images of various pneumonia types in animals, including bronchopneumonia and interstitial pneumonia.
• The text highlights the importance of understanding the different types and causes of pneumonia in animals for accurate diagnosis and treatment.