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Respiration Cambridge Biology Let’s watch a video! But first… • What is “respiration”? • NOT “breathing”! – This is the action of your lungs inhaling and exhaling air; “ventilation.” • Respiration = the process of breaking down glucose to use for ENERGY – If glucose were gasoline, then respiration would be the engine running in your car. • (you can’t go anywhere if the engine’s not running!) One more thing before video: Aerobic Respiration Anaerobic Respiration • Using O2 to break down glucose • NOT using O2 • “without air” • “with air” ~ “with oxygen” Aerobic Respiration • Using O2 to break down Glucose to release Energy for cells. • Glucose + Oxygen Carbon Dioxide + Water + Energy • C6H12O6 + 6O2 6CO2 + 6H20 + Energy But where did the Glucose come from? • You ate it! • Food breaks down into glucose molecules in the stomach (Digestion). • These glucose molecules enter your blood in the small intestine (Absorption). • Blood carries the glucose molecules to individual cells (Circulation). But where did the Oxygen come from? • You inhaled it (breathing). • In your lungs, your blood takes in O2 and lets out CO2. • This is called Gas Exchange. – (you’re exchanging one gas for another) • You need LOTS of surface area to exchange gasses quickly enough. – Lungs have about 70 square meters of S.A. • (about the size of a tennis court!) How do you get so much Surface Area in the Lungs? • Alveoli: very tiny sacs about 0.25 mm across • Alveoli are where Gas Exchange occurs – Gas can only exchange through a small distance – Blood capillary is right next to alveolus – Gas moves through capillary wall and alveolus wall • Distance of 0.001 mm Alveolar Gas Exchange Alveolar Gas Exchange Alveolar Gas Exchange Alveolar Gas Exchange Pathway of Inhaled Air • • • • • Mouth/nose Trachea R + L Bronchi Bronchioles Alveoli Pathway of Oxygen • Alveoli • Pulmonary (Lung) Capillaries • Pulmonary Vein – The blood in this Vein is Oxygenated (!!) – It is moving AWAY from the Lungs, but TOWARD the Heart. • Heart Aorta Arteries Arterioles Capillaries Body Cells • Respiration (conversion to Energy) happens in the Cell – Now the Cell has plenty of Energy! Pathway of Oxygen Pathway of Oxygen Pathway of Oxygen Question Time! • Where does the blood in Pulmonary Vein come from? (Hint: it is Oxygenated) – The Lungs • Where is it going? – The Heart • Where does the blood in the Pulmonary Artery come from? (Hint: it is Deoxygenated) – The Heart • Where is it going? – The Lung Oxygen Content of Air Inspired Air Expired Air Oxygen 21.00 % 16.00 % Carbon Dioxide 00.04 % 04.00 % Nitrogen 78.00 % 78.00 % Moisture Content Variable High Temperature Variable High How do we Breathe? • Ventilation: – Moving fresh air into lungs – Moving “used” air out of lungs • Ventilation happens because of changes in pressure that our body creates by contracting and relaxing muscles: – Diaphragm – Intercostals (“between ribs”) • Pleural membranes keep everything airtight. Pleural Cavity and Breathing Muscles Lungs & Diaphragm Inhalation • Diaphragm contracts – It moves DOWN because of its unique shape • Intercostal muscles contract – Making the ribs move UP • Volume increases inside pleural cavity. • Pressure decreases; creates a vacuum! • Air from outside flows into the Lungs. Diaphragm Inspiration Inspiration Exhalation • Diaphragm relaxes – Now it moves back UP • Intercostals also relax – Ribs can move back DOWN • Volume DECREASES • Pressure INCREASES – like a full balloon! • Air moves back out of the Lungs. Inspiration / Expiration Air Pressure in Model Lung How do Other Animals Breathe? • Diffusion: – Small animals with no ventilation structure • Gills: – Fish • Lungs: – Mammals – Birds – Herpetiles (Reptiles + Amphibians) • Skin: – Amphibians • Tracheae: – Insects Diffusion • O2 and CO2 diffuse in and out of the organism without a specialized organ • Small size • Large surface area Gills • Structures on fish that allow gas exchange with water. • Fish “pump” water over and through gills. Gills in Respiration Gills in Respiration Lungs • Allow gas exchange with air. • Bird lungs are structured to allow maximum gas exchange – Air moves through the lungs, not in-and-out like in mammals Bird Respiratory System Bird Respiration Lungs + Skin Tracheae • Network of branching tubes in insects. • Gas exchange occurs directly between tracheae and respiring cells. – No blood involved! • Insects breathe in and out through spiracles. Insect Anatomy Insect Tracheae Respiration WITHOUT Oxygen • “Anaerobic Respiration” • Many organisms respire anaerobically. – Even humans! (sometimes) • But Aerobic Respiration is more efficient – It yields about 19 times as much energy from one glucose molecule as Anaer. Resp. Anaerobic Respiration in Yeast • Yeast is a single-celled fungus. • Breaks down Glucose into Ethanol and CO2 • Can be used to make alcoholic drinks and bread – Ethanol = alcohol – CO2 bubbles = bread rises Yeast: Anaerobic Respiration Anaerobic Respiration in Humans • Only when our muscles run out of O2 – During strenuous exercise • We break down glucose into lactic acid to release useable energy. • Lactic acid is toxic! • So, we can’t do this very long. How do your Lungs stay Clean? • The air we inhale contains dust and bacteria. • Lung passages are lined with goblet cells and cilia, which keep unwanted particles from getting to the alveoli. Goblet Cells + Cilia • Goblet cells secrete mucus that traps dust and bacteria. • Cilia are tiny hairs that sweep the mucus up toward the back of your throat. • Then you swallow the mucus, along with everything else! – Bacteria die in your stomach’s acid and enzymes. Goblet Cells and Cilia Cigarette Smoke: Tar • Damages DNA in lung cells • This can result in lung cancer – Lung cells divide uncontrollably into a mass called a tumor. • If Tar (or other harmful chemicals) get into the blood, they can be carried to other parts of the body and cause other types of cancer. Cigarette Smoke: Tar • Tar can paralyze or destroy Cilia – Now they can’t sweep mucus out of the bronchial tubes! • Tar makes Goblet Cells excrete more mucus – Mucus slides down into lungs, creating a breeding ground for bacteria • Excessive coughing damages lining of tubes – Bronchitis: inflammation of bronchi • Damage to alveolar walls hinders gas exchange – Emphysema: difficulty getting enough O2 Cigarette Smoke • Also contains Carbon Monoxide (CO) • CO binds to hemoglobin in blood (just like O2) – But it never comes off! – So that means less places in the blood for O2 • Smokers often run short of O2 during energetic activity. Air Pollution: Particles • Coarse – 1-10 μm across – Filtered out in airways and bronchial tubes • Fine – 0.1 to 1 μm across – Not filtered out; can deposit in alveoli • Ultrafine – 0 to 0.1 μm across – Can penetrate cell walls, enter bloodstream, and travel to your brain! Particles Air Pollution: Sulfur Dioxide • Gas produced from burning fossil fuels – (industry + automobiles) • Mixes with water and becomes sulfuric acid (acid rain): – SO2 + H2O H2SO4 • SO2 turns to acid when enters your lungs and can damage the lining and alveoli. So… what should you do to protect your Lungs? • Don’t smoke! • Try not to breathe polluted air.