The Respiratory System with Labels | Game Quiz

The Pharynx: A Shared Pathway

The pharynx, commonly known as the throat, serves both respiratory and digestive functions. This muscular tube divides into three regions: the nasopharynx, oropharynx, and laryngopharynx. The nasopharynx contains adenoid tissue that helps fight infections, while the oropharynx manages both food and air passage. The epiglottis, a flexible cartilage flap, prevents food from entering the airway during swallowing.

The Larynx: Voice Box and Airway Protection

Located in the neck, the larynx houses the vocal cords and serves as an airway guardian. Its complex cartilage framework includes the thyroid cartilage (Adam's apple), cricoid cartilage, and paired arytenoid cartilages. The vocal folds stretch between these structures, vibrating during exhalation to produce speech sounds while helping regulate airflow.

The Trachea: The Windpipe's Structure

The trachea extends from the larynx to the primary bronchi, reinforced by C-shaped cartilage rings that prevent collapse during breathing. Its inner surface features ciliated epithelium, whose coordinated movement propels mucus and trapped particles upward toward the throat for removal. Specialized goblet cells produce protective mucus throughout the airway.

Primary Bronchi: The Main Airways

At the trachea's lower end, it divides into left and right primary bronchi. These main airways enter their respective lungs at structures called hila, where blood vessels and nerves also pass. The right primary bronchus sits more vertically than the left, explaining why inhaled objects more commonly lodge in the right lung.

Bronchial Tree: Branching Airways

The bronchi continue dividing into progressively smaller branches, forming the bronchial tree. Secondary bronchi supply individual lobes, while tertiary bronchi serve smaller lung segments. This branching continues through bronchioles to terminal bronchioles, with each generation becoming smaller and more numerous.

Alveoli: The Gas Exchange Units

At the smallest branches, respiratory bronchioles lead to alveolar ducts and finally to alveoli - tiny air sacs where gas exchange occurs. Each alveolus is surrounded by a network of capillaries, with only a thin membrane separating air from blood. This interface allows oxygen to enter the bloodstream while carbon dioxide exits.

The Pleural Membranes: Protective Coverings

The lungs are enclosed in pleural membranes - a double-layered serous membrane system. The visceral pleura adheres to the lung surface, while the parietal pleura lines the chest cavity. Between these layers, pleural fluid reduces friction during breathing movements and helps maintain negative pressure necessary for lung inflation.

Breathing Muscles: Powering Respiration

The diaphragm, a dome-shaped muscle separating the chest and abdominal cavities, serves as the primary breathing muscle. External and internal intercostal muscles between the ribs assist in breathing. During heavy exertion, accessory muscles in the neck and chest provide additional support for deeper breathing.

Blood Supply: Supporting Respiratory Function

The pulmonary arteries deliver deoxygenated blood from the heart to the lungs, while pulmonary veins return oxygenated blood. A separate bronchial circulation provides oxygen and nutrients to the airway tissues themselves. This dual circulation system ensures proper functioning of both gas exchange and airway maintenance.

Neural Control and Regulation

The respiratory center in the brainstem coordinates breathing patterns through complex feedback mechanisms. Chemoreceptors monitor blood oxygen, carbon dioxide, and pH levels, while mechanoreceptors in the airways and lungs provide information about lung expansion and airway conditions. This integration ensures appropriate ventilation under varying conditions.