37-3 The Respiratory System Copyright Pearson Prentice Hall

The Human Respiratory System The respiratory system consists of the: Epiglottis Trachea Nose Pharynx Larynx Lungs Bronchus Mouth Diaphragm Bronchioles The respiratory system is responsible for the exchange of oxygen and carbon dioxide. Air moves through the nose, pharynx, larynx, trachea, and lungs. After reaching the lungs, the trachea branches into smaller and smaller tubes called bronchioles, which end in alveoli, or air sacs. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall What Is Respiration? What Is Respiration? In biology, respiration means different things. Cellular respiration is the release of energy from the breakdown of food in the presence of oxygen (occurs in the?????) At the organism level, respiration is the process of gas exchange—the release of carbon dioxide and the uptake of oxygen that occurs between RBCs and alveoli Breathing is the actual mechanical intake of air Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Breathing BREATHING Lungs are sealed in pleural membranes inside the chest cavity. At the bottom of the cavity is a large, flat muscle known as the diaphragm. During inhalation the rib cage rises and the diaphragm contracts, increasing the size of the chest cavity. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Breathing During inhalation, the diaphragm contracts and the rib cage rises up. This expands the volume of the chest cavity. The chest cavity is sealed, so this creates a partial vacuum inside the cavity. Atmospheric pressure fills the lungs as air rushes into the breathing passages. During inhalation the rib cage rises and the diaphragm contracts, increasing the size of the chest cavity. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Breathing Often exhaling is a passive event. When the rib cage lowers and the diaphragm relaxes, pressure in the chest cavity is greater than atmospheric pressure. Air is pushed out of the lungs. Air Exhaled Rib cage lowers During inhalation the rib cage rises and the diaphragm contracts, increasing the size of the chest cavity. Exhalation Copyright Pearson Prentice Hall

The Human Respiratory System RESPIRATION Alveoli are grouped in clusters. A network of capillaries surrounds each alveolus. Pulmonary artery Pulmonary vein The respiratory system is responsible for the exchange of oxygen and carbon dioxide. Capillaries Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Gas Exchange RESPIRATION Gas exchange takes place in the alveoli. Oxygen diffuses into the blood. Carbon dioxide in the blood diffuses into the alveolus. Let’s examine this up close O2 CO2 Gas exchange occurs by diffusion across the membrane of an alveolus and a capillary. Capillary Copyright Pearson Prentice Hall