Respiratory System & Gaseous Exchange

• The respiratory system is responsible for the exchange of gases between the body's internal environment and external environment.
• Air enters through the nose or mouth, passes down the trachea (windpipe), branches into bronchi, then smaller tubes called bronchioles that end at tiny air sacs called alveoli where gas exchange occurs.
• Alveolar walls are thin to allow efficient diffusion of oxygen from the lungs into the bloodstream and carbon dioxide out of the bloodstream into the lungs.
• Oxygen diffuses across the alveolar wall into capillaries surrounding the alveoli, while carbon dioxide diffuses from the capillaries into the alveoli.
• Gas exchange takes place continuously during breathing.
• Gas exchange takes place by simple diffusion due to differences in partial pressures of oxygen and carbon dioxide on either side of the membrane.
• Inspiration involves contraction of diaphragm and intercostal muscles, increasing thoracic volume and decreasing intrathoracic pressure relative to atmospheric pressure.
• Expiration is a passive process caused by relaxation of diaphragm and intercostal muscles.
• Breathing involves two processes - inspiration (inhalation) and expiration (exhalation).
• Breathing involves inspiration (inhalation) when diaphragm contracts and rib cage expands, increasing lung volume and decreasing pressure inside the lungs compared to atmospheric pressure outside, causing air to flow into the lungs.
• Ventilation refers to the movement of air in and out of the lungs during breathing.
• Chemoreceptors


  Chemical sensors in the body that monitor oxygen and carbon dioxide levels in the blood.
• Pons Respiratory Centre


  A respiratory center in the pons of the brain that modifies the basic rhythm of breathing.
• Medullary Respiratory Centre


  A respiratory center in the medulla oblongata of the brain that controls the basic rhythm of breathing.
• Carbon Dioxide Transport


  The process of carrying carbon dioxide from body tissues to the lungs for exhalation via the bloodstream.
• Oxygen Transport


  The process of carrying oxygen from the lungs to body tissues via the bloodstream.
• Restrictive Lung Disease


  A type of respiratory disease characterized by a reduction in the capacity or volume of air the lungs can hold.
• Obstructive Lung Disease

  A type of respiratory disease characterized by difficulty emptying the lungs, with increased functional residual capacity and residual volume.
• Spirometry

  A pulmonary function test that measures lung volumes and capacities, useful in the diagnosis of respiratory disease.
• Total Lung Capacity


  The total volume of air the lungs can hold.
• Vital Capacity


  The maximum amount of air that can be exhaled after a maximum inhalation.
• Functional Residual Capacity


  The amount of air left in the lungs after a normal exhalation.
• Inspiratory Capacity


  The maximum amount of air that can be inhaled after a normal exhalation.
• Residual Volume


  The volume of air that remains in the lungs even after a forceful exhalation.
• Expiratory Reserve Volume

  The extra volume of air that can be exhaled after a normal exhalation.
• Inspiratory Reserve Volume


  The extra volume of air that can be inhaled after a normal inhalation.
• Tidal Volume


  The volume of air breathed in or out during a normal breath.
• Exhalation


  The process of breathing out, where the diaphragm relaxes and moves upward, and the intercostal muscles relax, reducing the size of the chest cavity and pushing air out of the lungs.
• Inhalation


  The process of breathing in, where the diaphragm contracts and moves downward, and the intercostal muscles contract, increasing the size of the chest cavity and drawing air into the lungs.
• Pulmonary Ventilation


  The process of moving air in and out of the lungs, also known as breathing.
• Pleurae


  A pair of thin membranes that surround the lungs and line the chest cavity, contributing to the mechanics of breathing.
• Lungs


  A pair of spongy, air-filled organs located in the chest that facilitate the exchange of gases between the air and the blood.
• Capillaries


  The smallest blood vessels that surround the alveoli and facilitate the exchange of oxygen and carbon dioxide with the bloodstream.
• Alveoli


  The tiny air sacs at the end of the bronchioles where gas exchange occurs between the air and the blood.
• Bronchial Tubes


  The air passages formed by the bronchi and bronchioles that transport air to different parts of the lungs.
• Bronchioles


  The smaller tubes branching off from the bronchi that go deeper into the lungs and act as air passages to ensure air reaches all parts of the lungs.
• Bronchi


  The larger tubes branching off from the trachea that carry air into the lungs.
• Trachea


  The tube that carries air from the nose and mouth to the lungs.
• Larynx


  The part of the respiratory system that contains vocal cords and is involved in speech production.
• Pharynx


  The part of the respiratory system that connects the nose and mouth to the trachea.