Topic 3: Respiratory System
Function of the Respiratory System
- Respiratory function:
- Gas transport for metabolism
- Move oxygen from air into pulmonary blood
- Clearance of carbon dioxide
- Non-respiratory function:
- filter blood
- chemical processing
- maintenance and defenses
- facilitate venous return
Definitions
- Respiration: interchanges of gases bw atmosphere and cells of the body
- Ventilation: transport of air to and from the lungs
- Gas exchange: O2/CO2 exchange bw air in the lungs and cells in the body
- Cellular respiration: oxidation of cellular molecules that produces CO2, water and ATP
Overall Gas Transport
1. Ventilation:
- movement of bulk airflow, delivering air to respiratory zone where gas exchange occurs
- Airways = system of tubular zones, deliver air, conditioning of the inhaled air (warmed to CBT,
humidification, filtration to prevent foreign objects and microorganisms entering the lungs)
- Nasal and oral cavities:
- inner surface = mucous membrane that warms and humidifies air
- Hair in nostrils act as filter
- Contains ciliated cells and mucus cells (goblet cells)
- Pharynx
- Connection bw nasal/oral cavity and the larynx
- Larynx
- Connects pharynx and the trachea: glottis and epiglottis prevents food from
entering trachea
- Trachea
- Flexible tube kept open by cartilage rings
- Inner surface lined with ciliated and mucus cells
- Coordinated cilia movements push the trash back towards the pharynx
- Bronchi
- Cartilage plates to maintain shape
- 1 tube per lung = primary bronchi
- Branches off to narrower tubes with less cartilage
- Bronchioles
- Smooth muscle
, - Alveoli - respiratory zone
- Single layer
of epithelial
cells
- Surrounded
by capillary
network
- Airway cross sectional area
- Increases dramatically
moving from trachea
to respiratory zone
- Velocity = flow/cross
sectional area
- Airway clearance
- Defensins: airway
“lysol” destroy
bacteria
2. Gas exchange/Lung diffusion:
- gas exchange bw respiratory
zone and blood
3. Circulation/Transport: blood
←> tissues, requires adequate
function of pulm and systemic
circulations
4. Tissue diffusion: RBS/plasma → tissues, passive diffusion
5. Internal respiration
- Pleural membranes: wet epithelial surfaces, cover the lungs
- Interpleural space filled with small amounts of fluid for lubrication of movements
Function of the Respiratory System
- Respiratory function:
- Gas transport for metabolism
- Move oxygen from air into pulmonary blood
- Clearance of carbon dioxide
- Non-respiratory function:
- filter blood
- chemical processing
- maintenance and defenses
- facilitate venous return
Definitions
- Respiration: interchanges of gases bw atmosphere and cells of the body
- Ventilation: transport of air to and from the lungs
- Gas exchange: O2/CO2 exchange bw air in the lungs and cells in the body
- Cellular respiration: oxidation of cellular molecules that produces CO2, water and ATP
Overall Gas Transport
1. Ventilation:
- movement of bulk airflow, delivering air to respiratory zone where gas exchange occurs
- Airways = system of tubular zones, deliver air, conditioning of the inhaled air (warmed to CBT,
humidification, filtration to prevent foreign objects and microorganisms entering the lungs)
- Nasal and oral cavities:
- inner surface = mucous membrane that warms and humidifies air
- Hair in nostrils act as filter
- Contains ciliated cells and mucus cells (goblet cells)
- Pharynx
- Connection bw nasal/oral cavity and the larynx
- Larynx
- Connects pharynx and the trachea: glottis and epiglottis prevents food from
entering trachea
- Trachea
- Flexible tube kept open by cartilage rings
- Inner surface lined with ciliated and mucus cells
- Coordinated cilia movements push the trash back towards the pharynx
- Bronchi
- Cartilage plates to maintain shape
- 1 tube per lung = primary bronchi
- Branches off to narrower tubes with less cartilage
- Bronchioles
- Smooth muscle
, - Alveoli - respiratory zone
- Single layer
of epithelial
cells
- Surrounded
by capillary
network
- Airway cross sectional area
- Increases dramatically
moving from trachea
to respiratory zone
- Velocity = flow/cross
sectional area
- Airway clearance
- Defensins: airway
“lysol” destroy
bacteria
2. Gas exchange/Lung diffusion:
- gas exchange bw respiratory
zone and blood
3. Circulation/Transport: blood
←> tissues, requires adequate
function of pulm and systemic
circulations
4. Tissue diffusion: RBS/plasma → tissues, passive diffusion
5. Internal respiration
- Pleural membranes: wet epithelial surfaces, cover the lungs
- Interpleural space filled with small amounts of fluid for lubrication of movements
