The Respiratory System Major Function of the Respiratory System: To supply the body with O 2 and dispose of CO 2

Processes involved in respiration  Ventilation-movement of air into and out of the lungs  External respiration- gas exchange between the blood (pulmonary capillaries) and the airsacs (alveoli) in the lungs  Transport of respiratory gases- movement of O2 and CO2 between the lungs and the tissues  Internal respiration- gas exchange between the blood (tissue capillaries) and tissue cells  * cellular respiration- utilization of O2 by cells for energy (ATP) production via oxidative phosphorylation

Basic Anatomy of the Respiratory System  Figure 22.1

Basic Anatomy of the Respiratory System  Upper Respiratory Tract Organs nasal cavity, pharynx, larynx Accessory structures: oral cavity, sinuses  Lower Respiratory Tract Organs trachea, bronchi, bronchioles, alveoli

Basic Anatomy of the Respiratory System  Figure 22.1

Respiratory Mucosa  mucous membrane lining the respiratory tract from the nasal cavity (and sinuses) to the bronchioles  epithelial layer is comprised predominantly of ciliated, simple columnar epithelial cells, with mucous-secreting goblet cells interspersed No cilia or goblet cells in smallest bronchioles or alveoli No cilia or goblet cells in smallest bronchioles or alveoli

Respiratory Mucosa

 Conducting Zone- structures from the nasal cavity up to and including the terminal bronchioles  Respiratory Zone- respiratory bronchioles (with attached alveoli) through the alveolar sacs

Fig 22.7up to nasal cavity

Alveoli  Microscopic sacs where gas (O 2 /Co 2 ) exchange occurs; lined with simple squamous epithelium (called type I cells or Type I pneumocytes)

Alveoli Figure 22.9c (not required)

 Alveoli, together with the pulmonary capillary endothelium→form the respiratory membrane

Alveoli  Microscopic sacs where gas (O 2 /Co 2 ) exchange occurs; lined with simple squamous epithelium (called Type I cells or Type 1 pneumocytes )  Alveoli, together with the pulmonary capillary endothelium→form the respiratory membrane (also called the alveolar-capillary membrane). Site of external respiration.  The thinness of the squamous alveolar cells and the pulmonary capillary endothelial cells makes the respiratory membrane very thin to allow efficient O 2 /CO 2 exchange

 Pleurae- serous membranes covering the lungs; contain pleural fluid  protect and lubricate the lungs

 Pleurae- serous membranes covering the lungs; contain pleural fluid  protect and lubricate the lungs The two pleurae are separate sacs