Respiratory System PDF

Body Systems Respiratory system  Respiratory system supports respiration Respiration is the release of energy from glucose in the form of ATP (which cells use for energy requiring processes) Occurs in all living cells in the body Usually aerobic (with oxygen) but can s...

Body Systems Respiratory system  Respiratory system supports respiration Respiration is the release of energy from glucose in the form of ATP (which cells use for energy requiring processes) Occurs in all living cells in the body Usually aerobic (with oxygen) but can switch to anaerobic respiration in the muscles due to lack of oxygen during vigorous exercise Produces carbon dioxide and water as wastes Respiratory system absorbs oxygen into the blood and removes carbon dioxide from the blood in the lungs (gas exchange)  The respiratory system Movement of oxygen and carbon dioxide between air & blood occurs by diffusion Diffusion requires concentration gradients Concentration gradients are maintained by breathing which ventilates the lungs and blood flow through the pulmonary capillaries Breathing movements are brought about by the diaphragm and intercostal muscles between the ribs Blood flow is maintained by the contraction of the right ventricle  Breathing movements Inhalation (a) Intercostal muscles contract moving the ribs up and out (b) Diaphragm contracts and is lowered (c) Volume of chest increases lowering pressure (d) Chest pressure is below atmospheric pressure (e) Air flows into the lungs  Breathing movements Exhalation (a) Intercostal muscles relax moving the ribs down and inwards (b) Diaphragm relaxes and is raised (c) Volume of chest contracts raising pressure (d) Chest pressure is above atmospheric pressure (e) Air flows out of the lungs  Gas exchange Oxygen diffuses from the air in the alveolus to the red blood cells in the capillary Carbon dioxide diffuses from the blood to the air in the alveolus Blood flow in the capillary and airflow from breathing maintain concentration gradients for both  How the alveoli carry out gas exchange There are millions, providing a large surface area for diffusion Walls are one cell thick so small distance for efficient diffusion Each has a good capillary network A film of moisture allows oxygen to dissolve before diffusing across  Cleaning the respiratory system Walls of the airways have cells that produce sticky mucus The mucus traps dust and bacteria Other cells have cilia, tiny hairs that move the mucus to the top of the airway Dust and bacteria are removed from the airway to prevent inflammation and infection  Smoking Cigarette smoke contains hundreds of chemicals Nicotine is highly addictive and causes CHD Other chemicals inactivate the cilia leading to accumulation of mucus and bronchitis (inflammation of the bronchial tubes) Alveolar walls may become inflamed and break down causing emphysema with shortness of breath and difficulty absorbing sufficient oxygen Chemicals in the tar cause normal cells to become cancerous, leading to cancers of the lung, larynx and bladder (by metastasis)  Effect of exercise on breathing Heavy exercise immediately increases heart and breathing rates but differently for fit and unfit people Stroke volume (blood pumped per beat) and tidal volume (air breathed per breath) also increase Changes increase ventilation and blood flow, providing steeper concentration gradients for gas exchange Breathing and heart rates fall after exercise but not immediately