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THE RESPIRATORY SYSTEM GAS EXCHANGE ASSESSMENT STATEMENTS 1. Distinguish between ventilation, gas exchange and cell respiration. 2. Explain the need for a ventilation system. 3. Describe and label a diagram of the ventilation system, including trachea, lungs, bronchi, bronchioles, and alveoli. 4. Draw and label a diagram of the ventilation system, including trachea, lungs, bronchi, bronchioles and alveoli 5. Explain the mechanism of ventilation of the lungs in terms of volume and pressure changes caused by intercostal muscles, the diaphragm and abdominal muscles. FAST FACTS ABOUT THE RESPIRATORY SYSTEM • The surface area of the lungs is roughly the same size as a tennis court. • A sneeze travels faster than a cough (60 vs. 100 mph). • A person at rest breathes about 12x-15x/min. 17,000x/day and over 6 million times/year. • The right lung (3 lobes) is slightly larger than the left (2 lobes). • Mean alveolar number is 480 million (Range: 274-790 million). An adult alveolus ranges in size from 0.2 - 0.3 mm. FUNCTIONS OF THE RESPIRATORY SYSTEM 1. The organs of the respiratory system are designed to serve as gas exchangers for the body. 2. The respiratory system filters, warms, and humidifies the air we breathe. 3. The primary function of the respiratory system is to deliver air to the circulatory system and remove carbon dioxide (waste) from the circulatory system, sustaining cell respiration. 4. Along with the circulatory system, the respiratory system aids in the distribution of heat. BASIC TERMINOLOGY Breathing/Ventilation: The mechanical process by which we breathe in and out. NOT the same as Cellular Respiration. External Respiration: The exchange of gases between the atmosphere and the blood. Internal Respiration: The exchange of gases between the blood and the body’s cells. THE RESPIRATORY SYSTEM THE PATH OF AIR 1. Air enters your mouth and nose. Hairlike structures called cilia trap foreign particles and sweep them toward the throat. Filtered air then passes through the upper throat (pharynx). 2. The epiglottis allows air to pass from the larynx to a the trachea (windpipe). The trachea branches into two large tubes called the bronchi—leading to the lungs. 3. Each bronchus branches into smaller tubes called bronchioles. Each of these small tubes branches into even smaller passageways, ending in individual air sacs (grape-like clusters) called alveoli. GAS EXCHANGE & DIFFUSION (THE PROCESS OF SWAPPING ONE GAS FOR ANOTHER) Occurs in the alveoli of the lungs. The alveoli are uniquely structured to facilitate gas exchange. • Oxygen diffuses from air in the alveolar sacs to the blood in the capillaries. • Carbon dioxide diffuses in the opposite direction (from an area of high to low concentration). • Both oxygen and carbon dioxide only need to diffuse through 3 cells (including the red blood cell). Remember: Diffusion is the random molecular motion of molecules -- molecules passively move from areas of higher concentration to area of lower concentration SIMPLE DIFFUSION VISUALIZING THE RESPIRATORY SYSTEM THE MECHANICS OF VENTILATION (INHALATION & EXHALATION) THE MECHANICS OF BREATHING • Inhalation is the act of taking air into the lungs. The diaphragm contracts, causing the chest cavity to expand as the diaphragm moves down. • During exhalation, the diaphragm relaxes and returns to its normal resting position. This reduces the size of the chest cavity as the diaphragm moves up. VENTILATION OF THE LUNGS (INHALATION) The external intercostal muscles contract, moving the ribcage up and out. The diaphragm contracts (flattens and moves down). These muscle movements increase the volume of the thorax. The pressure inside the thorax drops below atmospheric pressure. Air rushes/flows into the lungs from outside the body until the pressure inside the lungs equals atmospheric pressure. VENTILATION OF THE LUNGS (EXHALATION) The internal intercostal muscles contract, moving the ribcage down and in. The externals relax. The abdominal muscles contract, pushing the diaphragm up into a dome shape. The diaphragm relaxes. These muscle movements decrease the volume of the thorax. The pressure inside the thorax rises above atmospheric pressure. Air flows/rushes from the lungs to outside the body until the pressure inside the lungs falls and equals atmospheric pressure. THE MECHANICS OF VENTILATION (ANIMATIONS) AUTONOMIC NERVOUS SYSTEM CONTROL http://science.howstuffworks.com/life/humanbiology/lung3.htm • Respiration rate is controlled by the part of the brain called the medulla oblongata (brain stem). • Respiration rate can be influenced by: 1. Oxygen/CO2 concentration, blood pH, Chemical Irritants (cigarette smoke) and Signals from other brain regions (hypothalamus, cortex). 1. Drugs can influence respiratory system functioning. RESPIRATORY SYSTEM DISORDERS RESPIRATORY SYSTEM DISORDERS