Flashcards
Gas Exchange II - Mechanisms of Ventilation 1
Cards in this deck (16)
- 1How is ventilation achieved?Via convection of the respiratory medium over the gas exchange surfaces (active or passive).
This maintains a partial pressure gradient at the respiratory interface so fresh O2 is delivered and CO2 is removed. - 2What mechanical force is applied to achieve ventilation?Active muscle force, which is applied to the relaxed respiratory system.
- 3What is the key step in ventilation?The act of inspiration, all events that occur after the increase in the volume of the thorax is mainly passive.
- 4What is Boyle's Law?P1V1=P2V2
So as volume in thorax increases, pressure in interpleural layer falls. - 5Draw a diagram showing the process of InspirationActive process
Volume of thorax is increased as diaphragm contracts and external intercostal muscles contract. - 6Draw a diagram and describe the pressure and volume changes that accompany inspirationVolume of thorax increases, shown by change in tidal volume.
Pressure in interpleural space starts off negative w.r.t atmospheric pressure.
As pressure becomes even more negative it causes alveoli to expand, their volume decreases below atmospheric pressure.
As a result of pressure in alveoli at the end of the bronchilar tree becoming sub-atmospheric as air molecule mol/L stays the same, a pressure gradient is created.
Air flows into lungs until alveolar presusure=atmospheric pressure.
Whole process is passive. - 7Draw a diagram and describe the pressure and volume changes that accompany expiration.Elastic recoil of lungs and chest wall reduces volume of the thorax.
Ribcage moves down and in.
Diaphragm and intercostal muscles relax.
Volume of thorax decreases.
Causes interpleural pressure to increase as volume of interpleural space has gone back to its original volume.
Distending pressure on alveoli is removed.
Alveoli recoil.
Pair>Patm as air molecules in alveoli are under a higher pressure.
Another pressure gradient between alveoli and the atmosphere arises, as air flows passively from alveoli and is expelled from the lungs via 'bulk flow'. - 8Draw a diagram showing the lung volume changes in a single breathAir continues to move into lungs until the pressure gradient has dissipated = the peak of inspiration.
There's no air movement in/out of the lungs between the F.R.C and the P.O.I, and therefore is shows the static property of the lungs. - 9What is compliance?A value showing the elasticity and distention of the lungs by delta V as a function of delta P.
c=dV/dP - 10Dynamic Pressure-Volume Relationship, inspiration.Curve deviates to the right during inspiration because of resistive forces which oppose airflow.
A greater pressure is required to get air into the lungs. - 11Name the types of resistance affected inspirationAirway resistance, which is the resistance to movement of air.
Pulmonary tissue resistance - friction between lungs and chest wall. Pleural fluid decreases this resistance.
Inertia of air and tissues - the movement of a static state to a dynamic state i.e. sneezing/coughing. Not so much an issue in tidal breathing. - 12Dynamic Pressure-Volume relationship - Expiration. (5)Curve deviates to the left because resistive forces assisst airflow.
i.e. elastic recoil of lungs and chest wall
An elastic system always resists perturbation from its relaxed state.
Surface tension in alveolar surfactants oppose expansion of the alveoli.
Expiration can be active during forced exhalation as internal intercostal muscles and abdominal muscles contract. - 13Describe ventilation in birdsBird lung volume changes less than in mammals
Air moves through lungs from interconnected air sacs which do not participate in Gx as they don't have a rich blood supply. - 14Describe ventilation in frogsA positive pressure gradient as air has to be forced into the lungs
Lungs emptied by abdominal contraction, the glotti and abdominal walls alternate in cyclic contractions to ensure sufficient gas exchange. - 15Describe airway movements in insectsSpiracles line each body segment and penetrate within to allow direct diffusion between air and tissues of the body.
In larger insects contraction of abdominal muscles 'pump' air through tracheae. - 16Describe ventilation mechanism of bony fishTalk about floor of mouth and operculum pressure/volume changes shit.
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- User has deleted their subject information Flashcards on Gas Exchange II - Mechanisms of Ventilation 1, created by Deleted user on 27/12/2017.
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- Created by J yadonknow · Dec 20, 2017
- Copied by J yadonknow · Dec 27, 2017
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