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Ventilation, Perfusion, Diffusion - Coggle Diagram
Ventilation, Perfusion, Diffusion
Hypoxia: under-oxygenation of organs, tissues, & cells impairing normal metabolism.
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Ventilation: Inhalation
Primary Neuro-Chemical Control of Resp.:
Chemo receptors in the resp centre (medulla oblongata) sensitive to high levels of PCO2 stimulate us to take breath by sending messages via the-
- Phrenic nerve to diaphragm making it contract downwards
- Intercostal nerves t the intercostal muscles making the ribcage move up and out.
The intrathoracic space enlarges, the air pressure within decreases & air passively enters the lungs via the nose & mouth
Secondary Neuro-Chemical Control of Resp.:
Peripheral chemoreceptors in the arch of the aorta (aortic bodies) & in the carotid veins (carotid bodies) are sensitive to low levels of O2.
If the blood oxygen levels are low theses chemoreceptors send messages via the glossopharyngeal & vagus nerves to the resp. centre to initiate inspiration
Ventilation: Expiration
On full inspiration, stretch receptors in the lungs send messages to the resp. centre in the brain blocking the neural signals to inhale.
The intercostal muscles & the diaphragm relax causing the intrathoracic space in lungs to decrease & the intrathoracic air pressure to increase.
Air is pushed out via the trachea, nose & mouth
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Transport of O2
Understanding the relationship between the partial pressure of O2 (PO2) & O2 saturation (SO2) is very important
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O2 is carried in chemical combo. with haemoglobin as oxyhaemoglobin (98%) or in solution in plasma (2%)
Transport of CO2
Chronic lung diseases that effect the diffusion of gases across the alveolar membrane can lead to acid-base disturbances
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CO2 transported to the lung:
dissolved in plasma (5%),
bound to haemoglobin (10%),
bicarbonate buffer system (85%)
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