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Respiratory System

Respiratory System. Introduction. Functions. Provide for gas exchange Intake of O2 Removal of CO2 Regulate blood pH Sense of smell Produces sounds Filters, warms, moistens air Water, heat balance. 3 Major Steps. Pulmonary Ventilation Moving air in and out of lungs

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Respiratory System

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  1. Respiratory System

  2. Introduction

  3. Functions • Provide for gas exchange • Intake of O2 • Removal of CO2 • Regulate blood pH • Sense of smell • Produces sounds • Filters, warms, moistens air • Water, heat balance

  4. 3 Major Steps Pulmonary Ventilation • Moving air in and out of lungs External Respiration • Gas exchange between alveoli and blood Internal Respiration • Gas exchange between blood and body cells

  5. Structures and functions

  6. Upper Respiratory Nose (nares) • Warm, humidify, filter dust • Olfactory stimuli • Modify vocal sounds Pharynx • 3 regions • Tonsils, adenoids here • Eustachian tubes

  7. Lower Respiratory Larynx • “Voice box” • Thyroid cartilage • Epiglottis • Cricoid cartilage

  8. Lower Respiratory Trachea • Windpipe • Lined with ciliated mucous membrane; traps dust and moves it upward • C-shaped rings of cartilage keep airway open

  9. Lower Respiratory Bronchi, Bronchioles • Bronchi contain cartilage rings • Primary (1° ) bronchi enter lungs • Secondary bronchi branch from 1°, one for each lobe (3R, 2L) • Tertiary bronchi →→ terminal bronchi • Smaller airways have less cartilage, more smooth muscle

  10. Lower Respiratory Lungs • Right lung has 3 lobes, left has 2 • Surrounded by pleural membrane • Tertiary bronchioles divide into terminal bronchioles • These lead to respiratory bronchioles, which lead to the alveoli

  11. Lower Respiratory Alveoli • This is where gas exchange takes place • Surfactant cells secretes a substance that keeps the alveoli from collapsing • Macrophages help fight infection

  12. Pulmonary Ventilation Volume and pressure are inversely related Inhalation: • Contraction of diaphragm lowers the muscle and lung volume ↑ • Alveolar pressure ↓ • Air enters lungs to equalize pressure

  13. Pulmonary Ventilation Exhalation: • Relaxation of the diaphragm raises the muscle and lung volume ↓ • Alveolar pressure ↑ • Air rushes out

  14. Air Flow Frequency (f): Breaths/min; normal = 12 Tidal Volume (TV): volume moved in one normal breath • Normal = approx. 500ml • About 70% reaches alveoli • 30% remains in airway Minute Ventilation (MV): f x TV = 6000 ml/min

  15. Air Flow Inspiratory Reserve Volume (IRV): volume of air that can be inhaled beyond TV Expiratory Reserve Volume (ERV): volume of air that can be exhaled beyond TV Residual Volume (RV): air remaining in lungs after ERV

  16. Nature of Air Mixture of gases – N2, O2, CO2, H2O, etc. Each gas exerts a partial pressure Sum of partial pressures = atmospheric pressure Each gas diffuses down its pressure gradient • Example: O2 • In air, P = 105 mm Hg • In blood, P = 40 mm Hg

  17. Breathing Control Brain Centers: • Medullaryrhythmicity area • 2 areas in the pons Factors: • Voluntary adjustment (cortical) • Chemoreceptors • Limbic system; emotion, anticipation • Body temperature • Pain, airway irritation (cough, sneeze)

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