The pulmonary circulation is a critical component of the cardiovascular system and facilitates gas exchange between the heart and lungs. The lungs and heart are the main organs in the pulmonary circulation. In addition, the organs of the respiratory system are also involved in the circulating oxygen and carbon dioxide cycle. The process begins with the right ventricle pumping oxygen-poor blood into the pulmonary trunk, which bifurcates into the right and left pulmonary arteries. These arteries enter the lungs, where they divide into smaller arterioles and capillaries within the pulmonary alveoli, the primary site for gas exchange. After the gas exchange, pulmonary venules, which merge into larger vessels and eventually form pulmonary veins collected oxygen-rich blood. These vessels complete the pulmonary circuit by carrying oxygen-rich blood to the left atrium of the heart. Pulmonary arteries and veins show different histological features. The bronchi and bronchioles, which conduct the airways within the lungs, also play a supporting role in the pulmonary circulation. The bronchi are lined with pseudostratified ciliated columnar epithelium interspersed with goblet cells that secrete mucus to trap inhaled particles. The underlying lamina propria contains elastic fibres, smooth muscle and seromucous glands that facilitate airway potency and clearance. In conclusion, the pulmonary circulation is a finely tuned system that includes the right ventricle, pulmonary arteries, alveoli, capillaries and pulmonary veins. Each component exhibits specific histological features that support its function in gas exchange and blood oxygenation, which are crucial for maintaining respiratory and cardiovascular health.