Ventilation and Gas Exchange Flashcards
Definition of minute ventilation
Volume of air expired in one minute or per minute
Respiratory rate
Frequency of breathing per minute
Aveolar ventilation
Volume of air reaching the respiratory zone per minute
What is the anatomical dead space
Capacity of airways incapable of undertaking gas exchange
What is alveolar dead space
Capacity of airways that shoulder be able to undertake gas exchange but cannot
What is the physiological dead space
Sum of alveolar and anatomical dead space
What is hypoventilation
Deficient ventilation of the lungs, underable to meet metabolic demand - acidosis
What is hyperventilation
Excessive ventilation of lungs atop metabolic demand - alkalosis
What is hyperpnoea
Increase depth of breathing
What is hypopnoea
Decreased depth of breathing
What is apnoea
Cessation of breathing
What is dyspnoea
Difficulty in breathing
What is bradypnoea
Abnormally slow breathing rate
What is tachypnoea
Abnormally fast breathing rate
What is orthopnoea
Positional difficulty in breathing
Why is there residual volume when you exhale
There is surfactant and liquid that prevents the lung from collapsing
Capacities are the some of what
Sum of two or more volumes
What is the formula for minute ventilation
Tidal volume x breathing frequency
What is the alveolar ventilation formula
(tidal volume - dead space) x breathing frequency
What factors affect lung volumes and capabities
Body size - height, shape (less so)
Sex - males have larger lunger volume
Disease - breakdown of tissue, COPD lung capacity goes up
Age
Fitness - athletic parents
What is non-perfused parenchyma
Alveoli without a blood supply
No gas exchange
Typically 0
What is the conducting zone
No gas exchange
150mL in adults
Anatomical dead space
What is the respiratory zone
Where gas exhange happens
Alveolar ventilation
What can increase dead space in lungs
Anasethetic circuit
Snorkelling
Intubation
What can decrease the dead space lungs
Tracheostomy
Cicothyrocotomy
Don’t want airways to collapse
What is the chest wall relationship
Chest wall has a tendency to spring outwards
Lung has a tendency to recoil inwards
What happens during inspiration
Inspiration muscle effort + chest recoil > lung recoil
What happens during expiration
Chest recoil < lung recoil + expiratory muscle effort
Basic chest wall anatomy
Lungs are surrounded by visceral pleural membrane
Inner surface of chest wall is covered by a parietal pleural membrane
Pleural cavity is a fixed volume
Diagram of pleural cavity integrity
What is an example of negative pressure breathing
Healthy breathing
What is an example of positive pressure breathing
Resusitation
Mechanical ventilation
CPR
Fighter pilots
What does a negative transrespiratory pressure lead to
Inspiration
P(inside)-P(outside)
What does light ventilation require
Pulling force of diaphragm
What is the dalton law
Pressure of gas mixture is equal to the sum of partial pressures of gases in that mixture. Normally 100kPa
What is the fick laws
Moelcules diffus from regions of high conc to low conc at rate proportional to concetration gradient, surface area or diffusion capacity. Inversely proportional to thickness of surface
What is henrys law
At a constant temeprature, the amount of a given gas that dissolves in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibirum
What is Boyle laws
Volume of gas is inversly proportional to pressure of gas
What is charles law
At a constant pressure, the volume of gas is proportional to the temperature of that gas
What is the percentage of air
N - 78.09
o2 - 20.95
Ar = 0.93
C02 - 0.04
Other things - 0.01
How does the composition of air change in smoke
CO2 and CO increases
What happens to air composition in high altitude
Partial pressure is lower
Air is thinner
Diagram of inspired gas in airways
Conducting airways - saturate the air
What happens to air as it goes down the airways
Warmed, humidified, slowed and mixed
What happens as oxygen keeps binding to haemoglobin
Affinity for oxygen increases
What is allosteric behaviour
Protein changes shape in response to something that is bound or unbound
Allosteric behaviour of haemoglobin
What is the role of 2,3 - DPG
helps unload oxygen
What is cooperativity
The more 02 the more 02 affinity
What does a pulse oximeter determine
oxygen binding
don’t assume patient is fit and healthy as can have a low haemoglobin
What happens during a rightward shift of oxygen dissociation curve
Increase in temperature
Acidosis
Increase in 2,3 - DPG
Exercise
High CO2 (hypercapnia)
What happens during a downward shift
Anaemia
Impaired oxygen carrying capacity
What happens during an upwards shift
Polycythemia
What effect does carbon monoxide have on oxygen dissociation curve
Downwards and leftwards shift
Decreased capacity
Increase affinity
What is the relation of foetal haemoglobin to the oxygen dissociation curve
Greater affinity that adult HbA to extraxt oxygen from mothers placenta
What is the relation of myoglobin to oxygen dissociation curve
Myoglobin has a greater affinity than adult HbA to extract oxygen - exist in muscles, storage cupboard
Why is the oxygen saturation lower in tissues
Airway dumps blood with less oxygen which dilutes blood saturation
How much is the saturation of haemglobin as it travels back to lungs
75%
What is resting oxygen consumption
250mLm/min
What is HbC02
Carbaminohaemoglobin
How does C02 load into tissues
Why do we not produce a proportionate amount of C02 compared to O2
Due to the water as a byproduct
What is the pulmonary transit time
C02 is more soluble, less time
Gas exchange time normally 0.25s
