Respiratory System Flashcards
Functions of respiratory system:
Conducts air into & out of lungs Exchanges gases between air & blood Humidifies air Warms air Filters air
Alveoli:
Saclike structures surrounded by capillaries
site of exchange of oxygen and CO2
300 million in lung
Provides surface area where diffusion takes place
What are the two cell membranes that aid diffusion?
membrane of alveolar cells
membrane of cells of capillary wall
Visceral (pulmonary) pleura
outer surface of lungs
Parietal pleura
inner surface of thoracic cavity & diaphragm
Pleural fluid
lubricating fluid between 2 membranes
Intrapleural pressure
pressure in pleural cavity between 2 membranes; less than atmospheric pressure
Increase in volume of intrathoracic cavity
Increases lung volume
Decreases intrapulmonic pressure
Causes air to rush into lungs (inspiration)
Decrease in volume of intrathoracic cavity
Decreases lung volume
Increases intrapulmonic pressure
Causes air to rush out of lungs (expiration)
What do inspiratory muscles do?
increase intrathoracic cavity volume
Muscles that elevate ribs
external intercostals, scalenes, sternocleidomastoid, pectoralis minor
Diaphragm
Flattens as it contracts
Puts in motion pressure changes that cause inspiration
Contraction moves abdominal contents forward & downward
Expiration:
No muscular effort needed at rest
Passive recoil of diaphragm & other muscles decreases intrathoracic cavity volume
What muscles work during forced expiration to pull ribs downward?
Internal intercostals
Rectus abdominis
Internal oblique muscles of abdominal wall
Airflow equation
Airflow = P1 − P2/Resistance
What is P1-P2?
pressure difference between 2 areas
What can increase airflow?
Amplifying pressure difference between 2 areas
Decreasing resistance to airflow
What is biggest factor affecting airflow at rest?
Diameter of airway
What decreases resistance to airflow in exercise?
bronchodilation
Tidal volume
amount of air moved per breath
Pulmonary ventilation
anatomical dead space + alveolar ventilation