3. Ventilation in mammals Flashcards
What is ventilation? and whats it controlled by?
Ventilation consist of inspiration (breathing in) and expiration (breathing out). It’s controlled by the movement of the diaphragm muscles, intercostal muscle and ribcage
What happens during inspiration?
> The diaphragm and the intercostal muscle contracts.
This causes the ribcage to move outwards, upwards and flattened the diaphragm, increasing the volume of the thorax (the space where the lungs are)
As the thorax volume is increase, the pressure of the lungs decreased (below atmospheric pressure)
This causes the air to flow into the lungs
Inspiration is an active transport process - it requires energy.
What happens during Expiration?
> The diaphragm muscle and the intercostal muscle relax
The ribcage move inwards, downwards and the diaphragm becomes curved again, decreasing the thorax pressure
As the thorax pressure is decreased, the air pressure increased (to above its atmospheric pressure)
Air is forced out of the lungs
Expiration us a passive process - doesn’t require energy
What is tidal volume (TV)?
The volume of air in each breath
What is Vital capacity
The maximum volume of air that can be breathed in or out
What is breathing rate
How many breath are taken per unit time
Whats oxygen uptake?
The rate at which a person uses up oxygen
Hows a spirometer used?
> The spirometer has an oxygen - filled chamber with a movable lid
The person using the spirometer breaths through a tube connected to the oxygen chamber.
As the person breath in our out, the chambers moves up and down.
This movement is then recorded by a pen attached to the lid of the chamber - this writes on a rotating drum, creating a spirometer trace.
Or the spirometer can be hooked to a motion sensor - this will use the movements to produce electronic signals, which are picked up by a data logger.
The soda lime in the tube the subject breathes into absorbs carbon dioxide.
Why does the total volume of gas in the chamber decreases over time?
This is because the air thats breathed out is a mixture of carbon dioxide and oxygen. The carbon dioxide is absorbed by the lime water - so theres only oxygen in the chamber which the subject inhales from. As this oxygen get used up by respiration, the total volume decreases.
What should the person using the spirometer must do to get a valid result?
The person using it must wear a nose clip so make sure that they can only breath in and out from there mouth
How do you find out the breathing rate from the graph?
Look at how many peaks there are
How do you find out the tidal volume?
the length of the trace
How do you find out the vital capacity?
The length of the long trace
How do you find out the oxygen uptake?
By taking the average slope of the trace
