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Respiration Cambridge Biology
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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!)
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One more thing before video:
Aerobic Respiration Anaerobic Respiration Using O2 to break down glucose “with air” ~ “with oxygen” NOT using O2 “without air”
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Aerobic Respiration Using O2 to break down Glucose to release Energy for cells. Glucose + Oxygen Carbon Dioxide + Water + Energy C6H12O6 + 6O2 6CO2 + 6H20 + Energy
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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).
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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!)
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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 mm
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Alveolar Gas Exchange
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Alveolar Gas Exchange
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Alveolar Gas Exchange
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Alveolar Gas Exchange
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Pathway of Inhaled Air Mouth/nose Trachea R + L Bronchi Bronchioles
Alveoli
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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!
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Pathway of Oxygen
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Pathway of Oxygen
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Pathway of Oxygen
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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 Lung
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Oxygen Content of Air Inspired Air Expired Air Oxygen 21.00 % 16.00 %
Carbon Dioxide 00.04 % 04.00 % Nitrogen 78.00 % Moisture Content Variable High Temperature
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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.
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Pleural Cavity and Breathing Muscles
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Lungs & Diaphragm
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Inhalation Diaphragm contracts Intercostal muscles contract
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.
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Diaphragm
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Inspiration
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Inspiration
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Exhalation Diaphragm relaxes Intercostals also relax Volume DECREASES
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.
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Inspiration / Expiration
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Air Pressure in Model Lung
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How do Other Animals Breathe?
Diffusion: Small animals with no ventilation structure Gills: Fish Lungs: Mammals Birds Herpetiles (Reptiles + Amphibians) Skin: Amphibians Tracheae: Insects
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Diffusion O2 and CO2 diffuse in and out of the organism without a specialized organ Small size Large surface area
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Gills Structures on fish that allow gas exchange with water.
Fish “pump” water over and through gills.
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Gills in Respiration
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Gills in Respiration
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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
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Bird Respiratory System
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Bird Respiration
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Lungs + Skin
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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.
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Insect Anatomy
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Insect Tracheae
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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.
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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
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Yeast: Anaerobic Respiration
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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.
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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.
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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.
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Goblet Cells and Cilia
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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.
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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
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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.
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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!
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Particles
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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.
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So… what should you do to protect your Lungs?
Don’t smoke! Try not to breathe polluted air.
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