[020] pulmonary ventilation Flashcards
what is the fluid between visceral and parietal pleura called
pleural fluid
what is the function of the small quantity of lubricating fluid between pleural surfaces
lubricates the surfaces, allowing them to easily move over one another during breathing
in addition, surface tension generated holds the surface together
what is excess accumulation of fluid called
pleural effusion
if air penetrates between two layers of pleura,
what happens?
called pneumothorax
layers separate, lung collapses
movement of ribs would not be transmitted to lungs since changes in negative intrathoracic pressure would not be generated
functional residual capacity
the volume of gas contained in respiratory tract (lungs and airways) at beginning of inspiration under normal circumstances
to increase or decrease lung volume away from FRC requires activation of respiratory muscles
what muscles are active during normal resting inspiration
main muscle active : diaphragm
external intercostal may play a small part but not essential
are expiratory muscles active during normal quiet expiration
no
quiet expiration is a passive process so expiratory muscles are not active
how are lungs returned to FRC in normal quiet expiration
elastic recoil of lung tissue and effects of surface tension
‘pull’ lungs back to FRC
which muscles are recruited to achieve maximal inspiration
external intercostal muscles (play bigger part when inspiration is maximal)
accessory muscles of inspiration are recruited :
scalene muscles elevate first 2 ribs and
sternocleidomastoids raise sternum
what muscles are active during maximal expiration
abdominal muscles
- most important muscles recruited during active expiration, squeeze abdominal contents up against diaphragm, pushing it up into thorax
internal intercostal muscles also aid active expiration
what factors determine the maximum volume that can be inspired
determined by many factors including:
maximal force that can be generated by inspiratory muscles
compliance of chest wall and lungs
- compliances depend on posture, age and body size
what factors determine maximum volume that can be expired
chest wall and lung compliance
posture, body size and age
resistance of airways and tendency for airway to collapse
define
minute ventilation
volume of air entering and leaving nose or mouth per minute
define
alveolar ventilation
volume of air entering and leaving alveoli per minute
define
dead space ventilation
volume of air not taking part in gas exchange per minute
