Ventillation Ad Gas Exchange Flashcards
Tidal volume
Amount of air going in an out with each breath normally 500ml
Inspiratory reserve volume
Extra amount of volume you can get into lung on top of tidal volume
Expiratory reserve volume
Amount of air that can empty past tidal volume
Residual volume
Can fully empty lungs out due to lungs holding their structure which prevent collapse
Vital capacity
Difference between max air you can get into lungs and min air
Functional residual capacity
Everything below default position of lung capacity e.g. if you take in a deep breath and die, your lungs won’t empty all the way to bottom since that takes muscle effort, but to a baseline level due to elastic fibres of lung recoiling
Inspiratopry capacity
Everything above baseline value
Max volume of air a person can breathe after tidal volume
What factors affect lung volume and capacity
- Body and Size - The taller someone is, the larger their lungs (weight is not a factor)
- Sex - Average male has larger lung volume than the average female
- Disease - Can cause breakdown of the tissue inside
- Age - Older you are, lower the lung volume
- Fitness -If you have athletic parents, you are more likely to have larger lungs than someone w/o them
Dead space
Anatomical dead space is equivalent to conducting zone
Alveolar dead space is equivalent to non perfused parenchyma
Respiratory zone is where gas exchange occurs
Where gas exchange doesn’t occur
2 procedures that can decrease volume of someone’s dead space
Tracheostomy
Cricothyrocotomy
2 procedures that can increase volume of dead space
Snorkeling
Anaesthetic circuit
- What tendency does the chest wall vs lungs have to move?
Chest wall has tendency to spring outwards and lung has tendency to recoil inwards
When are recoiling forces equal
At end tidal expiration
Changes resulting in inspiration and expiration
Inspiratory muscle effort+chest recoil>lung recoil
Chest recoil<lung recoil +expiratory muscle effort
Membrane surrounding lungs
Visceral pleural membrane
Membrane covering inner surface of chest wall
Parietal pleural membrane
Pleural cavity
The gap between the pleural membranes which is a fixed volume
Pleural cavity contains
Protein rich pleural fluid
Which 2 conditions can compromise
Haemothorax where intrapleural bleeding occurs reducing ventilation ability
Pneumothorax were perforated chest wall causes lungs to collapse
Negative pressure gradient
Diaphragm is pulled down and rib cage out which reduces alveolar pressure below atmospheric pressure
Air flow into lungs
Normal breathing
Positive pressure breathing’s
When pressure in atmosphere is increased above alveolar pressure so air is forced into lung
Mechanical ventilation or cpr or fighter pilot
Diaphragm and respiratory muscles
Diaphragm creates pulling force when contracted
External intercostal muscle contract pulling rib cage in upwards and outward direction
Dalton’s law
Pressure of gas mixture is equal to some of partial pressure of gases in mixture
Ficks law
Molecules diffuse from high to low conc
Exchange SA and diffusion capacity inversely proportional to thickness of exchange surface
Henry’s law
At constant temp the amount of gas that dissolves jn a liquid is directly proportional to partial pressure of gas in equilibrium
Boyles law
At a constant temp the volume of a gas is inversely proportional to pressure of gas
Charles law
At constant pressure volume of a gas is proportional to temperature of gas
In accordance to Charles law which volume of air is slightly larger
Volume of expired air is larger as it is wet
How does composition of air being breathed in change when on oxygen therapy
Increase in oxygen partial pressure
Rest stay the same
How does composition of air change when on house fire
Decrease in oxygen partial pressure
Increase in carbon dioxide
Increase in carbon monoxide
High altitude
Composition stays the same but volume of each gas inhaled decreases
Inspired gas modifications
Warmed humidified slowed and mixed
Oxygen delivery
16mL/min
We need 250mL/min at rest so relying on dissolved oxygen isn’t enough
What type of protein is haemoglobin
Allosteric
When does right shift occur
Increased temp
Acidosis
Increased 2,3 DPG
Hypercapnia-higher pco2
Right shift means decreased affinity for oxygen
Left shift
Decreased temperature
Alkalosis
Hypocapnia
Decreased 2,3-DPG
Oxygen flux
Change in oxygen content in blood after unloading
Co2 loading
Moves just to blood where it binds to water making carbonic acid
Thus dissociated into bicarbonate
Thus moves out of blood and cl- moves j
Also bu do to Hb at amine end to make carb amino haemoglobin
How is Hb a good buffer
It binds to protons that carbonic acid dissociates into and maintains pH inside rbc so carbonic anhydrase can work
What increases dissolved oxygen in blood
Increased tidal volume
Minute ventilation
Gas entering and leaving lungs
Tidal volume times breathing frequency
Alveolar ventilation
Volume of air leaving alveoli
Tidal volume minus dead space times breathing frequency
