THE RESPIRATORY SYSTEM. Lecture 1: ORGANISATION OF THE RESPIRATORY SYSTEM. Respiration Lecture Series:

Transcription

1 THE RESPIRATORY SYSTEM Lecture 1: ORGANISATION OF THE RESPIRATORY SYSTEM Eamonn O Connor Trinity College Dublin Respiration Lecture Series: Mon Jan 16 th 9am: Organisation of the Respiratory System Mon Jan 16 th 2pm: Lung Mechanics Thu Jan 19 th 9am: Ventilation Mon Jan 23 rd 9am: Gas Exchange Mon Jan 23 rd 2pm: Gas Transport Thu Jan 26 th 9am: Respiratory Control Mon Jan 30 th 9am: Effects of Barometric Pressure Mon Jan 30 th 2pm: Effects of Exercise (?) Lecture Slides at: 1

2 Things to consider... The Respiratory System: Location? Active or passive? Voluntary or Involuntary? Resting Ventilation: Frequency? Volume? Lecture Outline 1) Overview of the Respiratory System 2) Anatomy of the Respiratory System 2

3 1) Overview of Respiratory System General Function: to obtain O 2 for use by body s cells & to eliminate CO 2 that body cells produce Encompasses two separate but related processes Internal Respiration Oxidative Phosphorylation External Respiration Exchange of O 2 and CO 2 between the atmosphere and body tissues Internal Respiration Cellular Respiration Refers to metabolic processes within the mitochondria, which use O 2 and produce CO 2 while deriving energy from nutrient molecules Stanfield 4 th Ed., Fig

4 External Respiration (4 Processes) Pulmonary ventilation (movement of air into lungs and out) Exchange O 2 & CO 2 between lungs (alveoli) and blood (pulmonary capillaries) by diffusion Transportation of O 2 & CO 2 between lungs and tissues Exchange O 2 & CO 2 between blood and body tissues by diffusion across systemic (tissue) capillaries External & Internal Respiration Sherwood 7 th Ed., Fig

5 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 2) Anatomy of the Respiratory System Respiratory Airways leading into the lungs The Lungs Structures of the Thoracic Cavity 5

6 Upper Airways of the Respiratory Tract Nasal Cavity (Nose) Oral Cavity Pharynx (common passageway for the respiratory & digestive systems) Air Passages of the Head & Neck Stanfield 4 th Ed., Fig 16.2 Respiratory Airways Stanfield 4 th Ed., Fig 16.2 Conducting zone (anatomical dead space) Airways from pharynx to lungs Larynx Conducting zone Respiratory zone Respiratory zone 6

7 Respiratory Airways cont. Conducting zone (anatomical dead space) Sherwood 7 th 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 orders of branching Up to 8 million tubules! Bronchioles Less than 1mm diameter No cartilage - risk of collapse Walls of elastic fibres prevent this Terminal Bronchioles 7

8 Functions of the Conducting Zone Air passageway 150ml volume Dead space volume Increase air temperature to body temperature Humidify air 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 4 th Ed., Fig

9 Structures of the Respiratory Zone Respiratory bronchioles Alveolar ducts Alveolar sacs Alveoli Stanfield 4 th Ed., Fig 16.5 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 9

10 Anatomical Features of Respiratory Tract Stanfield 4 th Ed., Fig 16.3 Alveoli Site of gas exchange 300 million alveoli per lung Surface area = tennis court! Rich blood supply Capillaries form sheet over alveoli Pores of Kohn permit airflow between adjacent alveoli (collateral ventilation) 3 cell types: Type 1 alveolar cells Make up the wall of alveoli, single layer of epithelial cells Type 2 alveolar cells Secrete surfactant Reduce surface tension in alveolar walls Help prevent alveolar collapse Alveolar macrophages Remove foreign particles Stanfield 4 th Ed., Fig 16.5 Sherwood 7 th Ed., Fig

11 Respiratory Membrane Barrier for diffusion Alveoli: Type 1 cells & Basement membrane Capillaries: Endothelial cells & Basement membrane 0.2 microns (µm) thick Stanfield 4 th Ed., Fig

12 Chest Wall & Pleural Sac Stanfield 4 th Ed., Fig 16.7 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 Sherwood 7 th Ed., Fig