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Respiratory System - Anatomy & Physiology

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  • What are the main functions of the nose in the respiratory system?
    The nose provides an airway for respiration; moistens, warms, filters, and cleans incoming air; provides a resonance chamber for speech; and houses olfactory receptors.
  • What structures form the upper respiratory system?
    The upper respiratory system includes the nose, nasal cavity, paranasal sinuses, pharynx, and larynx.
  • What is the role of nasal conchae in the nasal cavity?
    Nasal conchae increase the mucosal surface area to filter, heat, and moisten incoming air.
  • Describe the three regions of the pharynx and their functions.
    Nasopharynx: air passageway with pharyngeal tonsil; Oropharynx: air and food passageway with palatine and lingual tonsils; Laryngopharynx: air and food passageway continuous with esophagus.
  • What are the main functions of the larynx?
    The larynx provides an open airway, routes food and air into proper passageways, and produces sound via vocal cords.
  • What cartilage types compose the larynx?
    The larynx consists of hyaline cartilages (thyroid, cricoid, arytenoid, corniculate, cuneiform) and elastic cartilage (epiglottis).
  • How does the epiglottis protect the airway during swallowing?
    The epiglottis closes off the larynx during swallowing to prevent food or liquids from entering the airways.
  • What is the structure and function of the trachea?
    The trachea is a tube supported by C-shaped cartilaginous rings, lined with ciliated pseudostratified epithelium to propel mucus upward, and connects the larynx to the primary bronchi.
  • How do the bronchi branch and change structurally as they become smaller?
    Primary bronchi branch into secondary and tertiary bronchi, then bronchioles; cartilage decreases, epithelium changes from pseudostratified columnar to cuboidal, and smooth muscle increases.
  • What defines the respiratory zone of the respiratory system?
    The respiratory zone begins at respiratory bronchioles, leading to alveolar ducts and alveolar sacs where gas exchange occurs.
  • What is the respiratory membrane composed of?
    The respiratory membrane consists of type I alveolar cells, their basal lamina, and pulmonary capillary endothelium, allowing gas exchange.
  • What is the function of type II alveolar cells?
    Type II alveolar cells secrete surfactant, which reduces alveolar surface tension.
  • What are the pleurae and their functions?
    The pleurae are double-layered serous membranes; the parietal pleura lines the thoracic cavity, the visceral pleura covers the lungs, and pleural fluid lubricates to allow friction-free lung movement.
  • Explain Boyle's law in relation to pulmonary ventilation.
    Boyle's law states that pressure of a gas varies inversely with volume; during inspiration, thoracic volume increases, pressure decreases, and air flows into lungs.
  • What muscles are involved in quiet inspiration?
    The diaphragm and external intercostal muscles contract to increase thoracic volume during quiet inspiration.
  • How does forced expiration differ from quiet expiration?
    Forced expiration is active, using abdominal muscles to increase intra-abdominal pressure, while quiet expiration is passive, relying on lung elastic recoil.
  • What factors influence airway resistance?
    Airway resistance is influenced by airway diameter and length; resistance is usually low due to large upper airways and numerous smaller airways.
  • Define lung compliance and factors that reduce it.
    Lung compliance is the ease of lung expansion; it is reduced by decreased tissue elasticity, scar tissue, inflammation, or low surfactant levels.
  • What are tidal volume and vital capacity?
    Tidal volume is the air moved during quiet breathing (~500 ml); vital capacity is the total exchangeable air, sum of tidal volume, inspiratory reserve, and expiratory reserve volumes.
  • How is oxygen transported in the blood?
    About 1.5% of oxygen is dissolved in plasma; 98.5% is bound reversibly to hemoglobin in red blood cells.
  • What factors affect hemoglobin's affinity for oxygen?
    Increased temperature, CO2 partial pressure, H+ concentration, and BPG decrease hemoglobin's oxygen affinity, promoting oxygen release to tissues.
  • Describe the three ways carbon dioxide is transported in blood.
    CO2 is transported dissolved in plasma (7–10%), bound to hemoglobin (20%), and as bicarbonate ions (70%).
  • What is the Haldane effect?
    The Haldane effect describes how deoxygenated hemoglobin binds more CO2, facilitating CO2 transport from tissues to lungs.
  • What are the main respiratory centers in the brainstem?
    The ventral respiratory group (VRG) generates rhythm; the dorsal respiratory group (DRG) integrates sensory input; the pontine respiratory group modulates rhythm.
  • How do central and peripheral chemoreceptors regulate breathing?
    Central chemoreceptors respond to increased H+ from CO2 in cerebrospinal fluid; peripheral chemoreceptors in carotid and aortic bodies respond to low O2, high CO2, and pH changes.
  • What is the Hering-Breuer reflex?
    A protective reflex activated by lung stretch receptors that inhibits inspiration to prevent lung overexpansion.
  • How does exercise affect respiration?
    Exercise causes hyperpnea—deeper, faster breathing—to meet oxygen demand, driven by neural factors rather than changes in blood gases.
  • What changes occur during acclimatization to high altitude?
    Increased ventilation rate, lower hemoglobin saturation, and increased erythropoietin production to improve oxygen delivery.
  • What characterizes chronic obstructive pulmonary diseases (COPD)?
    COPD includes emphysema and chronic bronchitis, causing airflow obstruction, dyspnea, coughing, and frequent infections.