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What is external respiration?
- pulmonary ventilation
- exchange btwn lungs and blood
- transportation in blood
- exchange btwn blood and body tissues
What are the upper airways?
- Nasal cavity
- Oral cavity
What are the components of the respiratory tract?
- Conducting zone
- Respiratory zone
What are the structures of the conducting zone?
- Secondary bronchi (R has 3, L has 2)
- Tertiary bronchi (20-23 orders of branching)
- Bronchioles (less than 1mm diameter)
- Terminal bronchioles
What are the functions of the conducting zone?
- Air passageway (150 mL volume = dead space volume)
- Increase air temp to body temp
- Humidify air
What is the epithelium of the conducting zone comprised of?
- Goblet cells - secrete mucus
- Ciliated cells - move particles toward mouth
- Musuc escalator
What are the structures of the respiratory zone?
- Respiratory bronchioles
- Alveolar ducts
- Alveolar sacs
What are the functions of the respiratory zone?
- Exchange of gases btwn air and blood
- Mechanism is by diffusion
What is the epithelium of the respiratory zone comprised of?
Respiratory membrane - epithelial cells of alveoli, endothelial cells of capillary
What are some properties of alveoli?
- Site of gas exchange
- 300 million alveoli/lung
- Rich blood supply
- Alveolar pores
What are 3 types of alveolar cells?
- Type I alveolar cells - make up wall of alveoli
- Type II alveolar cells - secrete surfactant
- Alveolar macrophages
What is the job of the respiratory membrane?
Barrier for diffusion - type I cells + basement membrane, capillary endothelial cells + basement membrane
What are the structures of the thoracic cavity?
- Chest wall - rib cage, sternum, thoracic vertebrae, muscles
- Pluera - membrane lining of lungs and chest wall
What is the volume of the interplueral space?
What is the role of pressure in the pulmonary ventilation?
- Air moves from high to low pressure
- Inspiration - pressure in lungs less than atmosphere
- Expiration - pressure in lungs greater than atmosphere
How does intra-alveolar pressure vary?
Inspiration = negative (less than atmospheric)
Expiration = positive (more than atmospheric)
How does intrapleural pressure compare to atmospheric?
- Always negative under normal conditions
- Always less than Patm
- Varies w/ phase of respiration (at rest = -4 mm Hg)
What the negative pressure in pleural sacs caused by?
- Elasticity in lungs and chest wall
- Opposition of lungs and chest wall pulls on intrapleural space
- Surface tension of intrapleural fluid holds wall and lungs together
What is transpulmonary pressure?
- Palv - Pip
- Distending pressure across the lung wall
What is the equation for air flow?
What creates/changes pressure gradients in lungs?
What is boyle's law?
Pressure is inversely related to volume
What factors determine intra-alveolar pressure?
- Quantity of air in alveoli
- Volume of alveoli
What muscles are involved in inspiration?
- External intercostals
What muscles are involved in expiratory muscles?
- Generally, expiraiton is passive (unless exercising)
- Internal intercostals
- Abdominal muscles