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Published byMelvyn Kelly Modified over 9 years ago
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Physiology of the Respiratory System
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Objectives You will be able to… 1.Explain how air enters and leaves our lungs. Note: This covers all of the information in this presentation.
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Pulmonary Ventilation Ventilation: the movement of air into and out of the lungs, a.k.a. breathing. Two phases of ventilation: – Inhalation Drawing air into the lungs. – Exhalation Expulsion of air from the lungs.
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Inhalation How does air get into your lungs? – Respiratory muscles contract to enlarge the thorasic cavity. – Respiratory muscles include: Intercostal muscles – Located between the ribs. Diaphragm – Located below the rib cage between the thorasic and abdominal cavities.
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Inhalation Diaphragm – When it contracts it flattens out and moves downward. What will happen to the thorasic cavity? – This increases the vertical space (volume) of the thorasic cavity.
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Inhalation Intercostal Muscles – When they contract the rib cage moves out and up. – This also increases the amount of space (volume) in the thorasic cavity.
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Inhalation How does this change in volume allow us to breath? – There is pressure exerted on the thorasic cavity and lungs (greater than atmospheric pressure). – Pressure x Volume = constant PV = k (Boyles Law) – P = k/V If the volume of the thorasic cavity increases, the pressure will do what? – Decrease!!! – When the pressure exerted on the lungs decreases below atmospheric pressure, air is pushed into the lungs.
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Exhalation When the respiratory muscles relax, the thorasic cavity returns to its normal dimensions. – The rib cage moves back down and in. – The diaphragm thickens and moves upward. When the volume decreases, what happens to the thorasic cavity pressure? – Increases! When the pressure is higher than the atmospheric pressure, air is no longer pushed into the lungs.
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Inhalation and Exhalation
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