Gas Exchange at the Alveolus
The goal of both the cardiovascular system and the respiratory system is to deliver oxygen to the tissues and remove carbon dioxide. The respiratory system brings oxygen-rich air to the capillaries where oxygen enters the bloodstream. Carbon dioxide moves from the capillaries to the lungs and is released to the atmosphere during expiration. The respiratory system also aids the cardiovascular system through blood pressure regulation.
The respiratory system is involved in communication by allowing people to produce sound. As air passes through the nose or mouth through the pharynx and then the larynx, or voice box, the movement of air vibrates the vocal cords which produces sound. The vibration creates sound waves that then move back through the pharynx, nose, and mouth. In order for sufficient sound to be produced, the lungs have to be strong enough to provide adequate airflow to move the vocal cords.
Olfaction, or the sense of smell, occurs as air passes through the nasal passageways. Olfactory sensory neurons at the top of the nasal cavity have olfactory sensor proteins in their cell membranes that detect smells through subtle chemical changes in the inspired air. The cells are centered in the olfactory bulb which transmits the information to the olfactory nerve.
In addition, breathing functions as a type of pump that impacts venous return and lymph flow. During expiration, the vena cava (the large vein carrying oxygen-deficient blood back to the heart) is compressed, decreasing venous return and lymph flow. During inspiration, the vena cava is no longer compressed and both venous return and the flow of lymph is increased. Also during inspiration, blood flow from the lungs to the left atrium of the heart is increased, resulting in increased left ventricular filling. Increased ventricular filling leads to increased cardiac output. Movement of the diaphragm changes the pressures and space within the abdominal cavity. In this way, breathing helps to mobilize abdominal contents.