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Lecture 29
Lung Structure-Breathing
Term | Definition |
---|---|
External Respiration | Exchange of gases (O2 and CO2) btw body and environment. Internal respiration-use of O2 by mitcochondra |
Non-Respiratory Lung Functions | Water and heat loss,inc venous return,acid-base balance,speech,pathogen defense circulatory modification (ACE),sense of smell |
Lung Structure | Trachea-brochi-bronchiloes-alveoli. >20 generations of bronchioles. Alveoli are air sacs-sites of gas exchange |
Type 1 Cells | Epithelical cells~1 micron thick. Separate air from interstitial fluid. |
Type 2 Cells | In alveoli. Produce surfactant lowers resistance to alveolar opening. |
Lung Mechanics | Air flows from high-low pressure |
Atmospheric,Intra-Alovear, Intrapleural Pressures | A: 760 at sea level,600 at denver. 1-A: variable,exhale 1-2 > atm,inhale 1-2<atm. Ip: btw lungs anthoracic wall. Always 4 mmHg<atm. Lower pressure keeps lung always inflated |
Boyle's Law | PxV=constant. decV=incP and opposite |
Tidal Volume | Normal breathing volume. Inspiratory reserve volume-extra amount you can inspire. Expiratory reserve volume-extra amount you can expire. |
Inspiration | Regular-phrenic nerve from medulla. sends AP to diaphram. Diaphram contraction inc thorax volume, lowers pressure. DEc pressure causes inspiration. |
Extra Inspiration | External intercoastal muscles contract-expand thorax. |
Expiration | Normally passive. As diaphram relates, volume decreases,inc pressure,expiraiton |
Extra Expiration | Internal intercoastal muscles btw ribs contract. Abdominal muslces contract also squeeze thorax |
Compliance | Ease of lung expansion. Normally easy raises fibrosis (asbestos) of lungs lowers compliance. |
Alveolar Surface Tension | Adherence of H2O molecules creates surface tension on inside of alveoli. Surface tension must be overcome to open alveoli |
Surfactant | Several phospholipids, mix w/ water and lower surface tension. Also prevents edema in lungs. First made at 36th week of gestation. Glucocorticolds inc surfactant produciton in premature infants |
Anatomical Dead Space | Normal tidal volume is 500 mL. 150 mL of mouth,pharnx,trachea,bronchi,bronchioles is dead space. 350mL is normal alveolar inflation. Long,slow breathing minimizes dead space effect. Short,rapid breathing still must fill 150 mL dead space |