Mechanics Of Breathing Flashcards
(25 cards)
How is oxygen driven to the alveoli?
Down the pressure gradient - area of high pressure to low pressure
How does the difference between Pb and Pa differ between inspiration and expiration?
Ins = Pb > Pa
Exp = Pb < Pa
(Pb = atmospheric/barometric pressure)
(Pa = alveolar pressure)
When does alveolar pressure change
Secondary to thoracic volume changes
What muscles and directions aid in increasing thoracic volume
- diaphragm contracts and flattens
- ribs swing outwards and upwards
- internal inter costals relax and external intercostals contract
= increase in thoracic volume and decrease in thoracic pressure
What is Boyles law?
Pressure is inversely proportional to volume
Why is inspiration active and expiration active?
- Inspiration = active process using ex, int and innermost intercostals (need energy to contract muscles)
- Expiration (spontaneous breathing and = passive due to potential energy, it wants to deflate
What are the accessory muscles of respiration
Only needed when working hard to breath:
- scalenes in neck to elevate ribcage
- pec major
- sternecida mastoids
- trapesius and rectus abdominals
How is respiration and lung volume changes measured?
- via a spirometer
Tidal volume
Air moved in and out of lungs in normal breathing
Inspititory reserve volume
normal breath out, then take as deep as a breath in as possible then back to tidal volume - 3 L
Expiratory reserve volume
normal breath in then breath all air out as deeply as possible - 1,500 ml
Residual volume
cannot be measured by spirometry - 1 L left in lungs
all air is breathed out completely
Total lung capacity
Tidal volume +
Inspiratory reserve volume +
Expiratory reserve volume +
Residual volume
Vital capacity
What can be totally breathed in and totally breathed out:
Tidal volume +
Inspiratory reserve volume +
Expiratory reserve volume
Functional residual capacity
All air able to be breathed out of lungs after a normal breath in + residual volume (all air in lungs after normal breath in)
Expiratory reserve volume + residual volume
What is closing capacity
Closing capacity:
Further to the bottom to the small airways, there is less and less cartilaginous rings, so they have a tendency to close
The closing volume is when the small airways begin to close - between the start of airway closure and the residual capacity.
Closing capacity = closing volume (when airways close) + residual volume
As we age, what happens to closing capacity?
When do our lungs become poorly ventilated and what does this mean>
The capacity at which the alveoli begin to close increased:
BAD also known as airways start closing at a greater and greater capacity as we age.
If closing capacity exceeds Functional residual capacity, the alveolar dependant lung regions will be poorly ventilated - meaning poorer arteriole oxygen in older people
What is elastic recoil
When the lungs want to recoil and deflate to release all the potential energy accumulated inside of them
Conversely
On inspiration the chest wall wants to expand outwards - intrapleural pressure at its lowest
What is compliance and its calculation?
How willing something is to change/go along with something
Compliance = change in volume / change in pressure
Highest compliance at the residual capacity (more willing to inflate as more potential to inflate), lowest at total lung capacity
Is compliance equal throughout the lung? Why
No
More compliant at the bottom of the lung, as has more potential to inflate
Due to gravity as the alveoli at the bottom of the lung are the most compressed!
What does the compliance curve show?
That the highest compliance is at residual capacity (most willing to change and inflate) = steepest curve
Lowest at total capacity = plateaus
What is a capacity
2 or more volumes added together make a capacity
Name some diseases with DEcreased compliance and why they have DEcreased compliance
The lower the compliance the stiffer the lungs:
- pulmonary fibrosis
- congenital chest wall problems like Kyphoscoliosis
- circumferential burns - thick scar tissue - Eschar means chest wall can expand less - escharotomy to fix
What disease causes increased compliance? Why
Emphysema
Alveoli destroyed, lungs become more elastic, alveoli trap air
