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1/5/12 THE RESPIRATORY SYSTEM Lecture 1: ORGANISATION OF THE RESPIRATORY SYSTEM Eamonn O’Connor Trinity College Dublin Respiration Lecture Series: Mon Jan 16th 9am: Organisation of the Respiratory System Mon Jan 16th 2pm: Lung Mechanics Thu Jan 19th 9am: Ventilation Mon Jan 23rd 9am: Gas Exchange Mon Jan 23rd 2pm: Gas Transport Thu Jan 26th 9am: Respiratory Control Mon Jan 30th 9am: Effects of Barometric Pressure Mon Jan 30th 2pm: Effects of Exercise (?) Lecture Slides at: http://www.medicine.tcd.ie/physiology/courses/student_area Physiology 11-12 Respiratory Systems Lecture 1 1 1/5/12 Things to consider... The Respiratory System: Location? Active or passive? Voluntary Resting or Involuntary? Ventilation: Frequency? Volume? Physiology 11-12 Respiratory Systems Lecture 1 Lecture Outline 1) Overview of the Respiratory System 2) Anatomy of the Respiratory System Physiology 11-12 Respiratory Systems Lecture 1 2 1/5/12 1) Overview of Respiratory System General Function: to obtain O2 for use by body’s cells & to eliminate CO2 that body cells produce Encompasses two separate but related processes Internal Respiration Oxidative External Phosphorylation Respiration Exchange of O2 and CO2 between the atmosphere and body tissues Physiology 11-12 Respiratory Systems Lecture 1 Internal Respiration Cellular Respiration Refers to metabolic processes within the mitochondria, which use O2 and produce CO2 while deriving energy from nutrient molecules Stanfield 4th Ed., Fig 16.1 Physiology 11-12 Respiratory Systems Lecture 1 3 1/5/12 External Respiration (4 Processes) Pulmonary ventilation (movement of air into lungs and out) Exchange O2 & CO2 between lungs (alveoli) and blood (pulmonary capillaries) by diffusion Transportation of O2 & CO2 between lungs and tissues Exchange O2 & CO2 between blood and body tissues by diffusion across systemic (tissue) capillaries Physiology 11-12 Respiratory Systems Lecture 1 External & Internal Respiration Sherwood 7th Ed., Fig 13-1 Physiology 11-12 Respiratory Systems Lecture 1 4 1/5/12 Secondary Functions Short-term pH regulation (acid-base balance) Enabling speech, singing, & other vocalisations Defence against pathogens in the airways Removes, modifies, activates, or inactivates various materials passing through the pulmonary circulation Eliminates heat & water Assists venous return Nose serves as the organ of smell Physiology 11-12 Respiratory Systems Lecture 1 2) Anatomy of the Respiratory System Respiratory Airways leading into the lungs The Lungs Structures of the Thoracic Cavity Physiology 11-12 Respiratory Systems Lecture 1 5 1/5/12 Upper Airways of the Respiratory Tract Nasal Cavity (Nose) Oral Cavity Pharynx (common passageway for the respiratory & digestive systems) Stanfield 4th Ed., Fig 16.2 Air Passages of the Head & Neck Physiology 11-12 Respiratory Systems Lecture 1 Respiratory Airways Stanfield 4th Ed., Fig 16.2 Airways from pharynx to lungs Larynx Conducting zone Respiratory zone Conducting zone (anatomical dead space) Respiratory zone Physiology 11-12 Respiratory Systems Lecture 1 6 1/5/12 Respiratory Airways cont. Conducting zone (anatomical dead space) Physiology 11-12 Respiratory Systems Lecture 1 Sherwood 7th Ed., Fig 13-2 Structures of the Conducting Zone Trachea Bronchi Secondary Bronchi Right Side – 3 (to 3 lobes of right lung) Left Side – 2 (to 2 lobes of left lung) Tertiary Bronchi 20-23 orders of branching Bronchioles Less than 1mm diameter No cartilage - risk of collapse Up to 8 million tubules! Walls of elastic fibres prevent this Terminal Bronchioles Physiology 11-12 Respiratory Systems Lecture 1 7 1/5/12 Functions of the Conducting Zone Air passageway 150ml volume Dead space volume Increase air temperature to body temperature Humidify air Physiology 11-12 Respiratory Systems Lecture 1 Epithelium of the Conducting Zone Goblet cells Secret mucus & trap particles Ciliated cells Propel the mucus up the glottis to be swallowed or expelled ‘Mucus escalator’ Stanfield 4th Ed., Fig 16.4 Physiology 11-12 Respiratory Systems Lecture 1 8 1/5/12 Structures of the Respiratory Zone Respiratory bronchioles Alveolar ducts Alveolar sacs Alveoli Stanfield 4th Ed., Fig 16.5 Physiology 11-12 Respiratory Systems Lecture 1 Functions of the Respiratory Zone Exchange of gases between air & blood by diffusion Epithelium of the Respiratory Zone Respiratory membrane Epithelial cells of the alveoli Endothelial cells of the capillary Physiology 11-12 Respiratory Systems Lecture 1 9 1/5/12 Anatomical Features of Respiratory Tract Stanfield 4th Ed., Fig 16.3 Physiology 11-12 Respiratory Systems Lecture 1 Alveoli Site of gas exchange 300 million alveoli per lung Rich blood supply Surface area = tennis court! Capillaries form ‘sheet’ over alveoli Pores of Kohn permit airflow between adjacent alveoli (collateral ventilation) 3 cell types: Type 1 alveolar cells Type 2 alveolar cells Make up the wall of alveoli, single layer of epithelial cells Secrete surfactant Reduce surface tension in alveolar walls Help prevent alveolar collapse Alveolar macrophages Stanfield 4th Ed., Fig 16.5 Sherwood 7th Ed., Fig 13-2 Remove foreign particles Physiology 11-12 Respiratory Systems Lecture 1 10 1/5/12 Physiology 11-12 Respiratory Systems Lecture 1 Respiratory Membrane Barrier for diffusion Alveoli: Type 1 cells & Basement membrane Capillaries: Endothelial cells & Basement membrane 0.2 microns (µm) thick Stanfield 4th Ed., Fig 16.5 Physiology 11-12 Respiratory Systems Lecture 1 11 1/5/12 Chest Wall & Pleural Sac Stanfield 4th Ed., Fig 16.7 Physiology 11-12 Respiratory Systems Lecture 1 Pleural Sac Pleural Sac around each lung Side attached to chest: parietal pleura Side attached to lung: visceral pleura Intrapleural space filled with intrapleural fluid Volume = 15ml Physiology 11-12 Respiratory Systems Lecture 1 Sherwood 7th Ed., Fig 13-5 12
