3: Respiratory System Flashcards
What are the functions of the respiratory system?
- conducts air into and out of lungs
- exchanges gases between air and blood
- humidifies air
- warms air
- filters air
What does humidifying inspired air do?
prevents damage to membranes due to drying out
What does warming inspired air do?
helps maintain body temperature
What does filtering inspired air do?
- mucus traps airborne particles
- cilia move mucus toward oral cavity to be expelled
What are the saclike structures surrounded by capillaries in the lungs?
alveoli
What are alveoli attached to?
respiratory bronchioles
What do alveoli do?
site of exchange of oxygen and carbon dioxide (provide a tremendous surface area for diffusion)
How many alveoli are there?
300 million in lungs
What are the respiratory membranes that aid diffusion?
membrane of alveolar cells, membrane of cells of capillary wall
What is the pleural sac?
double-layered membrane that encases each lung
Where is the visceral (pulmonary) pleura located?
outer surface of lungs
Where is the parietal pleura located?
inner surface of thoracic cavity and diaphragm
Where is the pleural fluid location?
lubrication between to 2 membranes
What is the pressure in the pleural cavity between 2 membranes? what is it less than?
Intrapleural pressure, less than atmospheric pressure
How are the lung attached to the inner walls of the thorax?
Not directly… they are connected by a thin film of fluid (serous fluid) that is secreted by the inner surfaces of the two thin serious membranes (plurae)
What happens to lung volume when there is an increase of volume in the intrathoracic cavity?
increases
What happens to intrapumonic pressure when there is an increase of volume in the intrathoracic cavity?
decreases
What does an increase of volume in the intrathoracic cavity cause?
inspiration (causes air to rush into lungs)
What happens to lung volume when there is a decrease in volume of the intrathoracic cavity?
decreases
What happens to intrapulmonic pressure when there is a decrease in volume of the intrathoracic cavity?
increases
What does an decrease of volume in the intrathoracic cavity cause?
expiration (causes air to rush out of lungs)
What is the most important inspiratory muscle?
diaphragm
What happens to the diaphragm as it contracts?
flattens
What does contraction of the diaphragm do to abdominal contents?
Pushes them forward and downward