Respiratory System Bullets 002

• The pleurae are serous membranes that enclose the lungs.
• The visceral pleura directly covers the lungs.
• The parietal pleura lines the cavity of each hemithorax.
• The pleura space is a potential space between the two pleurae. Only few ml of serous fluid is found in the pleural space, to serve as lubricant.

• The right lung has three lobes, while the left lung has two lobes.
• The two lungs are separated by a space called mediastinum.
• There are approximately three hundred million alveoli in the lungs.
• The right lung is broader, but shorter due to the presence of the liver on the right side of the abdomen.
• Residual volume is the amount of air that remains in the lungs after forceful expiration. It prevents collapse of the lungs during expiration.
• Tidal volume is the amount of air that moves in and out of the lungs with each normal breath.
• Inspiratory reserve volume is the amount of extra air that can be inhaled, beyond the tidal volume.
• Expiratory reserve volume is the amount of extra air that can be exhaled after a normal breath.
• Total lung capacity is the total of all four volumes (residual, tidal, inspiratory reserve and expiratory reserve volumes).
• Functional residual capacity is the amount of air that remains in the lungs after normal exhalation.
• Pneumocytes. The type 1 pneumocytes line the alveoli, whereas the type 2 pneumocytes produce surfactant.
• The thorax provides protection for the lungs, heart and great vessels.
• The thorax is made up of 12 pairs of ribs, bounded anteriorly by the sternum and posteriorly by the thoracic vertebrae.
• The diaphragm is the main respiratory muscle for inspiration. It is supplied by the phrenic nerve.
• The following are the accessory muscles for inspiration: sternocleidomastoid, scalene, parasternal, trapezius and pectoralis muscles. They are used during increased work of breathing.
• Medulla oblongata is the primary respiratory center.
• Pons contains pneumotaxic center (responsible to the rhythmic quality of breathing) and apneustic center (responsible for deep, prolonged inspiration).
• Normal breath sounds are bronchial, bronchovesicular and vesicular.
• Bronchial breath sound is heard over the manubrium in the large tracheal airways. This sounds are high-pitched and loud.
• Bronchovesicular breath sound is heard over the bronchi. These sounds are moderate-pitched, with moderate-amplitude.
• Vesicular breath sound is heard all over the chest and heard best in the bases of the lungs. These sounds are low-pitched and soft.