Session 2 - Vent And Lung Mechanics Flashcards
(30 cards)
What generates automatic rhythmic impulses which guide involuntary breathing
Neurones in the resp center of the brain
How is air drawn into the lungs
By expanding the thoracic cavity , not vice versa
What is the tidal volume
Volume of air which enters and leaves the lungs
What is the correct term for completely filling your lung with air to the max capacity
Inspiratory reserve volume
What is the correct term for breathing out more than y ou would at rest
Expiration reserve volume
What is a residual volume
We cannot empty ALL the air in our lungs even with expiratory reserve volume, so residual volume is the amount of air remaining
Describe the concept of anatomical dead space
Only part of the tidal volume is used for gas exchange
Rest is in conducting part of bronchioles (ADS)
Describe what alveolar dead space is
Air which not perfused or damaged that do not take part in gas exchange
What is physiological dead space
Anatomical dead space + alveolar dead space
Describe the forces acting on the chest region after “rest” (after quiet respiration)
Inward - lungs elasticity and surface tension (favours small lung volumes)
Out - muscles associated with ribs have elasticity 9outward movement of chest wall)
Net effect - at rest, these forces balance each other and create negative pressure within intrapleural space relative to atmospheric pressure
What happens during inspiration
Contraction of diphragm and external intercostal muscles expands the thoracic cavity outwards from equal position
Pleural seal makes sure lungs expand along with thorax
As lung volume incr and pressure decr the atmospheric pressure flows from high to low and into the lung space
After quiet respiration, what lets the thoracic cavity and lungs return back to this normal deflated protein
The natural recoil of the lungs which is stronger than the chest elasticity itself
Describe the surface tension of the pleural cavity
The molecules within this cavity form a seal that holds the outer surface of the lungs to inner chest wall to ensure that the chest wall and lungs move together
Describe how the pleural pressure differs when inspiration
At beginning pleural pressure is negative relative to atmospheric
At breath in, more negative (adding positive to neg) due to expansion of the thorax
Returns t resting neg pressure at end of quiet respiration
What of the main muscles of expiration and inspiration
Inspire - diaphragm 70 % and external intercostal muscles 30 %
Exhale - none, passive process due to lungs elastic recoil
What are the accessory muscles of respiration
Forced inspiration - SCM, scalene (neck) serrated anterior and pec major (chest wall)
Forced expiration - internal intercostal muscles and abdominal wall muscles
When are accessory muscles of inspiration used
When ventilation increases
Exercise
For what 2 things is energy used for when it comes to breathing
Inspiration (to stretch the lungs)and to (overcome airways resistance)
What is compliance
Stretchiness of the lung
Where do the elastic properties of lungs come from and why is this important to know
Elastic tissue
Surface tension forces of alveoli
To stretch lungs elastic recoil must be overcome
Describe how surface tension in alveoli work
Want to “collapse” lung
As alveoli fill due to lung filling , opposing surface tension forces wants to minimalise surface area due to gas liquid interface and therefore brings it back down
What is surfactant and its significance
What secretes it
Type 2 pneumocytes
Phospholipid structure made of proteins
Disrupt interaction between fluid molecules on surface therefore reducing surface tension
Describe how surface tension differs between a large alveoli and small alveoli
As alveoli expands, surfactant molecules (in between water) are spread further apart increasing the amount of surface tension exerted making it harder for them to expand (as it expands, surface tension incr) (less efficient)
As it shrinks, the surfactant molecules are closer together meaning so is the surfactant reducing the surface tension making them easier to expand (more efficient) (surfactant reduces surface tension as area of alveolus decreases)
What law determines the pressure within one alveoli bubble
Law of Laplace
