Mechanics of breathing Flashcards
what is the partial pressure of 02 in the air?
21kPa / 160mmHg
what is the partial pressure of 02 in the alveoli?
100mmHg / 13kPa
what is the partial pressure of C02 in the alveoli?
40mmHg / 5kPa
What is residual volume?
the amount of air remaining in the lungs after maximal expiration
what is function residual volume?
the amount of air left in the lungs after passive exiration
what is inspiratory capacity defined as?
the maximum amount of air that can be inspired
TV + IRV
what is vital capacity defined as?
The maximum amount of air that can be expired from a maximum inspiration
TV+IRV+ERV
what is the normal volume for Vital capacity?
4600ml
what is the normal volume for tidal volume?
500ml
350 from inspired air and 150ml from dead space
how effective is breathing?
70% effective because 150ml of the 500ml tidal volume is kept as anatomical dead space
what is total lung capacity defined as?
the total capacity of the lungs - maximum inspiration and maximum expiration + residual volume.
VC+RV
what is the average inspiratory reserve volume and expiratory reserve volume?
3000ml IRV
1100ml ERV
why does vital capacity decrease with age?
as muscles weaken and the lungs become less elastic
what is the capacity of volume of air that each lung can hold ?
3litres per lung
therefore 6 litres In total
what is the volume of the anatomical dead space?
150ml
what zone is the trachea known as?
conductance zone as gas exchange doesn’t occur
what zone is the alveoli known as?
respiratory zone
what accessory muscles are involves in inspiration?
(external intercostal and diaphragm)
sternocleoidmastoid and scalene muscles
what accessory muscles are involves in expiration?
expiration is passive unless there is extreme expiratory load
muscles involves are internal intercostal and abdominal wall muscles
what does Pip stand for?
partial pressure of intra pleural cavity
what is the value of Pip?
-3mmHg
what recess provides space into which the lungs can expand on inspiration?
costodiaphragmatic
what is the main determinant of airway resistance?
radii of airways
large diameter = high resistance
small diameter = low resistance
(this is due to the total surface area available)
what is the difference between alveolar pressure and intrapleural pressure defined as?
transpulmonary pressure (Pt)
is the transpulonary pressure always positive or negative?
positive
is the intra pleural pressure always positive or negative?
negative
is the intrathoracic pressure always positive or negative?
it can be positive or negative (depending on the stage of respiration)
