Ventilation and gas exchange Flashcards
(33 cards)
Draw and label the graph that show tidal volume
which is the least useful clinically? Why
Expiratory capacity- it fluctuates (in tidal volume area)
What is the equation for minute ventilation?
what is the normal breathing frequency
Tidal volume X Breathing frequency
normal breathing frequency is 12 breaths/min
What is the equation for alveolar ventilation
(Tidal volume - Dead space ) X breathing frequency
What are the factors affecting lungs volumes and capacities?
- Body size- larger height increases lubing volume
- Fitness- more training increases volume and capacity
- sex- males have higher lung volume
- Disease-
- Age- chronological (time) and physical( how well your body looks)
What is dead space? What are the areas of dead space in a healthy individual - describe it’s features
Spaces in airway where THERE IS NO VENTILATION (gas exchange)
in healthy individuals it is the conduction zone of the trachea and brochi
CONDUCTING ZONE
- 16 generations
- No gas exchange
- 150 mL in adults at FRC
- THIS IS THE ANATOMICAL DEAD SPACE
Describe the features of the respiratory zone of the airway
- 7 generations
- Gas exchange
- typically 350mL in adults
- air reaching here is equivalent to alveolar ventilation
What is the physiological dead space in healthy and unhealthy individuals ?
Healthy- physiological dead space is equal to anatomical dead space
unhealthy- physiological dead space = anatomical plus ALVEOLAR SPACE
What is alveolar dead space?
Alveoli without blood supply - non perfused parenchyma
No gas exchange
Typically 0mL in healthy adults
What are the ways of increasing or decreasing dead space
Increase
- anaesthetic snorkelling
decrease
- tracheostomy or cricothyroidostomy
can you think of any more
Describe the relationship between the chest wall and the lungs
Chest wall wants to expand outwards and lung wants to collapse inwards.
at functional residual capacity, they are at equilibrium- Chest recoil= Lung recoil
Describe the forces between chest wall and lungs that results to inspiration and expiration
Inspiration
Inspiratory muscle effort + chest recoil is GREATER than lung recoil
Expiration
Chest recoil is LESS than LUNG RECOIL and expiratory muscle effort
How is the chest wall connected to the lungs- anatomy
Lung is connected via pleural cavity
visceral pleural is connected to lungs
the parietal pleura is connected to inner surface of thoracic cavity
theres a pleural cavity between the layers containing protein rich fluid- it is also a semi-vacuum and a potential space- a fixed volume
Pleural fluid interacts non-abrasively.
What are the different ways in which the pleural cavity integrity can be disturbed, what will this cause the lungs to do?
Haemothorax in which there’s interpleural bleeding- which will cause pressure on the lung
Pneumothroax- when there’s a punctured lung or perforated chest wall; it will cause lungs to collapse
What are the different types of breathing in relation to pressure
Negative pressure breathing- when pressure in alveolar is reduced to be lower than atmospheric pressure of (1 atm.). E.G. normal breathing mechanism
positive pressure breathin- when atm pressure is increase to be greater than alveolar pressure.E.g fighter pilots use this, CPR
3 compartment model
what leads to expiration and inspiration
- Negative transrespiratory pressure leads to inspiration
- positive trans mural pressure leads to expiration
What is the order of FEV1/FVC ratio for restrictive, normal and obstructive disease
calculate the peak respiratory volume fo the graph (L/min)
Order in ascending order: Obstrucitve, normal, restrictive
Find the gradient for the smallest unit of time
Describe Henry’s Law
At a constant temperature, 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 equilibrium with a liquid
Content of dissolved gas = partial pressure of gas X arterial gas
What are the key gas laws that describe gas behaviour
- Henry
- Dalton
- Charles
- Boyle’s
- Ficks
What are the ways in which inspired gas is modified before it reaches the lungs.
how does Paritel pressure of each gas changes
It is WARMED, HUMIDIFIED, SLOWED, and MIXED as it passes down respirator tree
pO2 decreases; pH2O and pCO2 increases
The amount of oxygen dissolving due to Henry’s law isn’t enough (16mLmin-1) from the body? What is the VO2 of the body and how does it achieve this
VO2 is 250mL/min
This is achieved by Haemoglobin cooperative effect
What are the different types of haemoglobin during normal human development
HbA- 2 alpah and 2 beta
HbA2 - 2 alpha and 2 delta
HbF- 2 alpha and 2 gamma
Describe the allosteric behaviour of haemoglobin; what chemical binds to it when it’s saturated and what is it’s significance?
2,3-DPG; This puts the haem in a tensed state enabling unloading of oxygen onto tissue
For the oxygen dissipation curve, what causes left shift, i.e. higher affinity of oxygen?
- REDUCED BLOOD temperature
- alkalosis - high O2
- Hypocapnia- low CO2
- low 2,3 DPG
In an oxygen dissociation curve what causes right shift, i.e. lower affinity for o2
- HIGHER BLOOD temperature
- Acidosis
- Hypercapnia
- high 2,3, DPG
