CBIO2210 Week 8 Notes
CBIO2210 Week 8 Notes CBIO2210
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This 4 page Class Notes was uploaded by Elise Weidner on Tuesday March 1, 2016. The Class Notes belongs to CBIO2210 at University of Georgia taught by Rob Nichols in Spring 2016. Since its upload, it has received 29 views. For similar materials see Anatomy and Physiology II in Anatomy at University of Georgia.
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Date Created: 03/01/16
CBIO 2210 Notes 3/1/16 Top Hat Questions 1. Which of the following is NOT performed by the respiratory system? a. Transport of respiratory gases from the lungs to the tissues(job of circulatory system) b. Clean and moisten incoming air c. Providing an airway for the ventilation pf air into and out of the lungs d. Provide a surface for the exchange of gasses between air and blood 2. Which of the following regions of the respiratory system is the only region that is NOT kept open by hyaline cartilage? a. Nose b. Trachea c. Bronchi d. Bronchioles 3. Which of the following regions of the respiratory system is not lined by ciliated epithelium? a. Alveoli (would get clogged if there was mucus that the cilia move) b. Nasal cavities c. Trachea d. Left primary (main) bronchus 4. When the volume of a chamber containing a gas increases, the pressure____. This principle is known as _____ a. Decreases, Hooke’s law b. Decreases, Boyle’s law c. Increases, Hooke’s law d. Increases, Boyle’s law 5. Atelectasis can occur when: a. The intrapleural pressure equalizes with atmospheric pressure 6. Air moves into the lungs because: a. The pulmonary pressure (P pul) is less than the atmospheric pressure (P atm) 7. What causes greatest influence on resistance? a. Bronchiole diameter Mechanics of Breathing Our breathing method works, even when atmospheric pressure changes Just manipulating the pressure relative to atmospheric pressure, it needs to be a little lower than atm pressure so the air will come in Intrapulmonary pressure (P pul) o Combination of pressure in all the alveoli in the lungs o Hard to measure o Fluctuates with breathing because to breathe in this pressure must be lower than P atm to breath out it must be higher than the P atm. o Equalizes with P atm between inspiration and expiration Intrapleural pressure (P ip) o Must always be negative (less than both P pul and P atm) o Also fluctuates with breathing Transpulmonary Pressure (P tp) o Difference between P pul and P ip o Should always be positive (shouldn’t ever be 0) o P pul-P ip=P tp o Not directly measurable o Zero is not absolute zero o When pressure in alveoli is less than P atm them breath in and volume of air incoming increases o P ip around 5 mmHg lower than P atm Atelectasis (collapsed lung) o Most are spontaneous o Traumatic injury that admits air and/or blood into pleural cavity result: P ip equalizes to P atm o Plugged bronchioles (such as in COPD) loss of air pressure in bronchioles (need air pressure to keep them inflated, no cartilage rings) leads to progressive collapse of alveoli o happens if P tp is 0 Inspiration Active process- require constant muscle contraction of the diaphragm Inspiratory muscles contract to increase thoracic volume: o diaphragm (when relaxed) o external intercostals-outer layer of muscles between ribs (when exercising) get really high delta P (how fast air flows in) P pul goes negative allowing air to go in Expiration Can be passive Relaxed expiration is a passive process o “controlled collapse” (uncontrolled when an injury) o Balance of forces trying to collapse your lungs: Pro-collapse: elastic fibers & fluid lining alveolus Anti-collapse: negative Pip & surfactant Inspiratory muscles relax Elastic recoil decreases intrapulmonary volume P pul goes positive Forced expiration is an active process using internal intercostals (deepest layer on rib cage) and abdominal muscles o Coughing, sneezing, blowing out candles Factors Influencing Ventilation This inward - outward “flow” of air is not so easy Inspiratory muscles must consume energy to overcome factors that hinder air movement: o Resistance o alveolar surface tension o compliance Note: if there is obstruction in the airway, then expiratory muscles will be needed to overcome resistance, even during relaxed expiration (e.g., COPD) Greatest contributor to airway resistance is the bronchioles because they are so small Asthma Acute asthma attacks o reduction of bronchial diameter due to inflammatory response (histamine) o R is so high that flow is impaired or stopped regardless of ΔP Epinephrine dilates bronchioles o part of normal sympathetic response or administered exogenously (from outside) o albuterol (inhaler): short-acting β2-receptor agonist (acts like epinephrine), we eventually develop a resistance to it o formoterol: long-acting (Symbicort)-block histamine and “cort” part of symbicort anti-inflamitory Alveolar Surface Tension Surface tension = attraction of liquid molecules for each other at gas-liquid interface o resists expansion of surface area o The greater the surface tension, the greater the pressure necessary to inflate the lungs. o Surface tension pulls alveoli in (would collapse lungs if not for surfactant/Type II alveolar cells) Surfactant reduces surface tension o Type II alveolar cells o equalizes surface tension in all alveoli, thus reducing the pressure necessary to inflate the lungs o Infant respiratory distress syndrome (IRDS) sufficient surfactant not produced until around 30 – 32 weeks of fetal development Compliance (how easy something is to inflate) Compliance is the measure of how easy it is to inflate something. o high compliance = easy to inflate (and vice versa) Two primary factors: o distensibility (“stretch”) of the lung tissue generally high in healthy lungs o alveolar surface tension reduces compliance kept low by surfactant Higher compliance means less respiratory effort Fibrosis (major enemy of compliance) o due to chronic inflammation/infections o results in replacement of healthy elastic fibers with non-elastic scar tissue Key Concepts Flow of air in and out of the lungs (ventilation) is determined by pressure gradients. Pressure gradients are determined by volume changes (Boyle) Inspiration is always active; whereas quiet expiration is a passive balancing act of pro- collapse and anti-collapse forces Resistance and compliance are factors that affect ventilation o resistance impairs flow (primarily at bronchioles due to greatest cross-sectional area) o surface tension impairs compliance (reduced by surfactant)