BIOL 1344 Lecture 16 Outline of Last Lecture I. Respiratory SystemA. Upper Respiratory SystemB. Lower Respiratory System Outline of Current Lecture II. Anatomy of Lung – Mechanics of BreathingA. Quiet BreathingB. Forced BreathingC. Lung Pressure D. Air FlowE. Lung Diseases Current LectureEach lung is covered by two membranes. The inner layer is the visceral pleura, the outer is parietal pleura. The space between the two is called the pleural cavity and contains about 3 ml of fluid. Elastic tissue pulls the lungs inward while the body wall pulls it outward which results innegative pressure. The two pleural thorax are separate, if one is punctured the negative pressure is lost and the lung collapses. This is call pneumothorax but the person can still live using one lung.Quiet Breathing: During quiet (normal) breathing the inspiration (breathing in) is active while the expiration (breathing out) is passive. Spinal nerves send out acetylcholine which causes muscle contraction. During this contraction the external intercostals raise the rib cage and the diaphragm becomes flat rather than its relaxed dome shape which is a movement of 1-2 cm dueto the phrenic nerve.Forced Breathing: an example of this is heavy breathing during exercise. Both inspiration and expiration are active. The muscles used during inspiration are the sternocleidomastoid, spinae erectae, scalenes, and the serratus posterior superior. During expiration the muscles are the internal intercostals, transverse abdominis, thoracic transversus, serratus posterior inferior, and the external oblique muscles. Lung Pressure: Alveolar Pressure or Intrapulmonary Pressure is the pressure inside of the lungs. Normal pressure here is 0 = 760 mmHg. During inspiration, it drops to -1 (759 mmHg) and the These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.rib cage rises and the diaphragm lowers. During expiration, pressure reaches +1 (761 mmHg) and the diaphragm rises, rib cage lowers.Intrapleural Pressure is outside of the lungs in the pleural cavity. This is always negative. During inspiration (about 2 sec.) pressure drops to -6 (754 mmHg) then during expiration (about 3 sec.) pressure goes back up to -4 (756 mmHg). Air flow: Boyles Law states the P1V1 = P2V2 at a constant temperature. The flow of air = the change in Pressure/resistance and Resistance = 1/r4 while r = radius. Ventilation Rate: TV(tidal volume, 500 ml) X Rate of breath (about 12 per minute) =6000 ml/minHowever, the dead space in the trachea and other tubes in which there is no gas exchange equals about 150 ml. Therefore, the Alveolar Ventilation Rate is actually closer to 4.2 liters/min. TV (500) – Dead Space (150) X 12 = 4200 ml or 4.2 litersForced Vital Capacity (FVC) – air forced out/inFEV1 – forced expiratory volume, air pushed out in 1 secondFEV1/FVC = % of air leaving the lungs in the first sec. which should be about 80%Lung Disease: Constrictive – COPD (chronic obstructive pulmonary disease) and asthma. Air flowis constricted to less than 80%. Restrictive – tuberculosis, edema, fibrotic lung. Respiratory surface is restricted so there is less air in/out although no change in the FEV1/FVC
View Full Document
Unlocking...