Mechanics of ventilation Flashcards
What is ventilation defined as?
The movement of air in and out of the lungs
What determines the total volume of air breathed in per minute?
volume of each breath x by the number of breaths per minute
What is the tidal volume?
The volume of air entering/leaving in a single breath
In which zone does gas exchange occur?
The respiratory zone, e.g the alveoli
What is Physiologic dead space?
Alveolar + Anatomic dead space
What makes up tidal volume?
A dead space component and an alveolar component
What is the total lung capacity?
The maximum amount of air that the lungs can hold
What is the functional residual reserve?
volume of air left in the lungs after a normal breath
What is the residual volume?
Minimum volume of air remaining in the lungs after a max expiration
What is the vital capacity?
max volume of air that can be moved out during a single breath following a max inspiration
What occurs during inspiration?
Diaphragm contracts and flattens, external IC muscles pull the ribs cranially upwards (using fibres) this increases the volume of the thoracic cavity
What are the two different types of expiration?
Forced and Passive Expiration
What is passive expiration?
Expiration in animals that does not require muscle contraction
What is Forced Expiration?
Active process that pushes more air out of the lungs
What is an example of physiologic dead space being useful?
Panting
Why is the difference in pressure mostly governed by the alveolar pressure?
Atmospheric pressure stays constant
What is the transpulmonary pressure?
The difference between intra-alveolar and intra-pleural pressure
What is the intrapleural pressure?
The pressure outside of the lungs but within the thoracic cavity (within pleural sac)
What is the intra-alveolar pressure?
Pressure inside of the alveoli
What happens to respiratory activity during exercise?
respiratory muscle activity increases
What is ventilation synched with in running mammals?
Ventilation is synchronised with gait in canter and gallop but not walk or trot
How does moving of quadrupeds whilst running effect ventilation?
Flexion/extension of the spine can increase/ decrease the size of the thoracic cavity
What are three factors that will effect ventilation rate?
1) Changes in atmospheric pressure
2) Changes in resistance
3) Change in interpleural pressure
How does the diameter of the bronchioles effect ventilation rate?
Decreased diameter of bronchioles (due to disease) will increase the resistance
What is laminar air flow?
Straight air flow (think blowing through a straw)
What type of air flow increases when the diameter of the bronchioles increase?
laminar air flow
What opposes the expansion of the alveoli?
At an air-water interface, the water molecules are attracted to eachother rather than the air- this creates surface tension
Which opposes the expansion of the alveoli
What counterracts the surface tension in the alveoli?
Surfactant, which is a detergent-like mixture of lipids, proteins and ions
What is the name of the cells that secrete surfactant?
Type-II alveolar cells
What does high lung compliance mean?
High lung compliance means that the lungs will expand easily
What is pneumothorax?
collapsed lung, this trauma causes the pressure inside and outside the lung to equalise
What enables ribcage expansion in birds?
Hinged ribs
What do birds have instead of alveoli?
air capillaries that radiate from cylindrical parabronchi
