Introductory Mammalian Physiology (PHOL0002) Notes - Respiratory System

The Respiratory System
The Respiratory System
 Lungs
o Purpose of lungs
 Decrease the diffusion distance
 Allows efficient exchange of gases
 Remove CO2
 Take in O2
o Lung structure




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 Nasal cavity / mouth  trachea  primary bronchi  divides into secondary and
tertiary bronchi  bronchioles  terminal bronchioles  alveoli
o 17 million branches
o 300 million alveoli
o Structure of the bronchus and bronchioles




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 Cartilage
o Around the outside of the bronchi
o C-shaped cartilage
 Allows diameter of tubes to be manipulated
o Allow parts of airways to remain open under significant pressure
 Epithelium
o Lines airways
o Mucus
 Traps particulate matter
 Traps micro-organisms

, The Respiratory System
o Cilia
 Hair like projections that beat to move debris out of the airway
 Glands
o Make and release mucus onto the surface
 Smaller bronchioles
o Less cartilage – more prone to collapse
o Less mucus and cilia
o Alveolar epithelial structure




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 Alveolar cells
o Thin
 Nucleus
 Cell membranes
 Capillary
o On surface of alveolus
o Carries O2 bound to haemoglobin
o Loses CO2
o Takes up O2
o Haemoglobin saturation




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 Arterial blood
o Blood is 97% saturated with O2
 Venous blood
o Blood is 75% saturated with O2
o O2 dissociation curve