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The Respiratory System - Lab

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The Respiratory System - Lab

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  1. The Respiratory System - Lab

  2. The main function of the respiratory system is to supply oxygen to, & eliminate carbon dioxide from the body In order to accomplish this task, the respiratory system must work in conjunction with the cardiovascular system

  3. Anatomy Overview Nasal cavity The respiratory tract includes: Nose (nasal cavity) Pharynx (nasopharynx, oropharynx, laryngopharynx) Larynx Trachea Bronchi (primary, secondary (lobar), tertiary (segmental)) Bronchioles Terminal bronchioles Alveolar ducts Alveoli Pharynx Larynx Trachea Bronchi Bronchioles Respiratory bronchioles Left Lung Right Lung Alveolar duct Alveoli

  4. “Respiration” refers to the overall exchange of gases between the atmosphere, blood & cells • Respiration involves 3 processes • Pulmonary ventilation • Gas exchange (gas diffusion) • External respiration • Internal respiration • Gas transport

  5. Physiology of Respiration Pulmonary Ventilation – “exchange” (movement) of gases between the atmosphere & lungs; movement of gases occurs because of pressure differences between the atmosphere (atmospheric pressure (Po)) & lungs (intrapulmonic pressure (Pi)) • Two phases of ventilation: • Inspiration (inhalation) • Expiration (exhalation) Po at sea level = 760 mmHg

  6. Pulmonary Ventilation - Inspiration • Inspiration (inhalation) - • Active process involving contraction of diaphragm & external intercostal muscles Contraction of diaphragm & external intercostal muscles  increased volume of thoracic cavity  tension on parietal & visceral pleura  increased volume of lungs  decreased intrapulmonic pressure  air flows in

  7. Pulmonary Ventilation - Expiration • Expiration (exhalation) - • normally passive due to relaxation of diaphragm & external intercostal muscles • can be made active (forced expiration) due to contraction of abdominals & internal intercostal muscles Relaxation of diaphagm/external intercostals  decreased volume of thoracic cavity  decreased lung volume  increased intrapulmonic pressure  air flows out

  8. Gas Exchange (gas diffusion) • External respiration - the diffusion of O2 & CO2 between the alveoli & blood across the respiratory membrane • occurs because of pressure differences of each gas within alveolar air & pulmonary (deoxygenated) blood • results in creation of oxygenated blood

  9. Gas Exchange • Internal respiration – the diffusion of O2 & CO2 between the blood & interstitial fluid across the endothelium of systemic capillaries • occurs because of pressure differences of each gas between systemic (oxygenated) blood & interstitial fluid • results in creation of deoxygenated blood

  10. Lung Volumes & Capacities • Respiratory frequency (f) – number of ventilations (inspiration+expiration) per minute. (12-20 breaths/min) • Tidal volume (TV) - amount of air moved in or out of the lungs during a normal breath (500 ml) • Minute ventilation (VE=TV x f)- amount of air inhaled or exhaled in one minute (6000 ml/min)

  11. Lung Volumes & Capacities (cont.) • Inspiratory reserve volume (IRV) – amount of air that can be inhaled after a normal inspiration (above the resting TV) (2500ml/1900ml) • Inspiratory capacity (IC = TV+IRV) – amount of air inhaled after a normal expiration (3000ml/2400ml)

  12. Lung Volumes & Capacities (cont.) • Expiratory reserve volume (ERV) – amount of air that can be exhaled after a normal expiration (1000ml/700ml) • Residual volume (RV) – amount of air remaining in lungs even after maximal expiration (1200ml/1100ml avg –25% of VC)

  13. Vital capacity (VC=TV+IRV+ERV) – maximum amount of air you can exhale, following a maximal inhalation (4000ml/3100ml) • Total lung capacity (TLC=TV+IRV+ERV+RV) – maximum amount of air in your lungs, following a maximal inhalation (5200ml/4200ml)

  14. Control of Respiration • Unconscious control of breathing occurs through the activity of the respiratory centers of the brain • Medulla oblongata – “Rhythmicity center” controls basic pattern of breathing; inhale 2 seconds, exhale 3 seconds • Pons – has 2 centers (apneustic & pneumotaxic centers) that can unconsciously modify the rate & depth of respiration Respiratory centers can be influenced by mechanoreceptors (i.e. stretch receptors in lungs) & chemoreceptors (sensitive to CO2 levels, arterial pH, & O2 levels) in the body, as well as by higher brain centers