Movement of air from the external environment through the airways into the alveoli during breathing.
An inspiration and an expiration.
Conducting zone( 1 of 2 airways beyond the larynx)
extends from the top of the trachea to the beginning of the respiratory bronchioles - contains no alveoli and has no gas exchange with the blood
Respiratory zone( 1 of 2 airways beyond the larynx)
extends from the respiratory bronchioles down contains alveoli and is the region where gases exchange with the blood
Functions of the Conducting Zone
Provides a low resistance pathway for air flow by changes in contraction of the smooth muscle Provides defense by way of cilia, mucus, and macrophages Moistens and warms the air Phonates(vocal cords)
Cause of Cystic Fibrosis
mucous layer becomes thick and dehydrated, obstructing the airways Results from impaired Cl- channel involved in the secretory process
Type I alveolar cells
Flat epithelial cells that form a single cell thick air-facing surface
Type II alveolar cells
Thicker specialized cells that are dispersed between the Type I alveolar cells Produce surfactant
Plural surface coating the lung Attached to the lung by connective tissue
attached to and lines the interior thoracic wall and diaphragm
The exchange of air between the atmosphere and alveoli
Movement of air from high pressure to low pressure F= Change in P/ R *P= (alveolar pressure- atmospheric pressure) R=resistance
What happens when alveolar pressure is less than atmospheric pressure?
driving force for air flow is negative and inspiration occurs
What happens when alveolar pressure is greater than atmospheric pressure?
Driving force for air flow is positive and expiration occurs.
Volume and pressure are inversely related : P1V1=P2V2
Boyle's Law related to Expiration
The lungs act as the container effecting the alveolar pressure During expiration, lungs decrease in volume, thereby increasing alveolar pressure
Boyle's Law and Inspiration
Lungs increase in volume, alveolar pressure decreases
The difference in pressure between the inside and the outside of the lungs
Pressure inside the lungs
air pressure inside the alveoli
Pressure outside of the lungs
pressure of the intrapleural fluid surrounding the lungs
tendency of an elastic structure to oppose stretching or distortion.
atmospheric air enters the intrapleural space, causing the intrapleural pressure to increase Causes lung to collapse because the transpulmonary pressure acting to hold the lung open is eliminated.
What happens when contraction of the inspiratory muscles actively increases the thoracic dimensions?
The lungs are passively forced to enlarge The pressure inside the alveoli decreases to less than atmospheric pressure
What causes bulk flow of air
Pressure difference: alveolar pressure < atmospheric pressure Causes air to move into airways from a high atmospheric pressure to a low alveolar pressure Air flow ceases when alv pressure equals atm pressure
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