37.3 The Respiratory System • Respiration….2 meanings we learn – Cellular Respiration: release of energy from food in presence of oxygen – Organism Respiration: process of gas exchange between organism and the environment Human Respiratory System • Basic function is O2 and CO2 exchange between blood, air, and tissues structures • Pharynx: passageway for air and food • Larynx: contains vocal cords • Trachea: wind pipe – Epiglottis covers entrance when swallowing • Bronchi: passageways branching to each lung • Bronchioles: small passageways in each lung • Alveoli: air sacs that are site of gas exchange Air pathway… • nose/mouthpharynxlarynxtracheabronchi bronchioles alveoli Cilia and Mucus • Air must be warm, moist, and filtered • Mucus – Moistens air, traps inhaled particles • Cilia – Sweep trapped particles away from lungs, towards pharynx • Swallowed or spit out Gas Exchange • 150 million alveoli – Lots of surface area…why important? • Diffusion of O2 and CO2 across capillaries – Diffussion….what is it, why does it work here? • Inhale Breathing – Diaphram contracts, rib cage moves up – Vacuum created, air rushes in to fill it • Exhale – Diaphram relaxes, rib cage lowers – Pressure in lungs increases, air rushes out Breathing cont… • Works only because chest is sealed – Puncture breaks seal, keeps vacuum from forming • “sucking chest wound” Breathing controls • Medulla oblongata regulates – Monitors CO2 level – As CO2 increases, your urge to breath increases – Usually not dependent on O2 • Carbon Monoxide, airplanes, free diving….. Tobacco and respiratory sys • Tobacco contains nicotine, CO, and tar • Nicotine and CO paralyze cilia – Smoker cough Smoking Diseases • 30 % of smokers live to 80 • 55% of nonsmokers live to 80 • Chronic bronchitis, emphysema, lung cancer • Emphysema: loss of elasticity of lung tissue – What would this do? Diseases cont… • Lung cancer: 160,000 diagnosed each year – Spreads rapidly, few survive 5 years • Heart disease: smoking doubles risk – Smoking causes blood pressure to rise • What is high blood pressure called???
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