Chemistry 8 Gases and Respiration Flashcards
Explain Boyles Law
An increase in the pressure of an enclosed mass of gas will result in a decrease in the volume. A decrease in the pressure of an enclosed mass of gas will result in an increase in the volume. The pressure of a gas varies inversley with its volume.
Key roles in body and healthcare where movement of gas play a role:
Breathing and exchange of alveolar blood gases. (diffusion of gases and transport of gases) Equipment used to aid our breathing (breathing apparutus, C02 therapy, atmospheric pressure)
Standard atmospheric terms
•Standard atmospheric pressure (P) Average = ~1013 hPa= 101.3 kPa Variation = ~ 980 hPa–1025 hPa Positive Pressure: P > Atmospheric Negative Pressure: P
Along what concentration gradient do gases move?
Movement of gases is always from a region of HIGH pressure to a region of LOW pressure
In what part of the body can we apply Boyles law?
The chest, as the Diaphragm acts to seal the cavity.
Describes the process of inspiration.
Active process of breathing in Intercostals muscles elevate the rib cage Diaphragm contracts/flattens, moving down.
Describes the process of expiration.
Passive process of breathing out Elastic recoil Intercostal muscles relax, rib cage descends Diaphragm returns to resting position (relaxes and ascends)
(Respirators) Explain what negative pressure ventilators do and why they would be used
Negative pressure ventilator = “Iron Lung” •Help to assist or control breathing •Mimics physiological process of breathing by periodically altering pressure in chamber •Lungs expel or inhale air when muscle control lost, e.g. polio
(Respirators) Explain what positive pressure ventilators do and why they would be used
Positive pressure system •More popular today •Oxygen actively pushed into the lungs to create pressure difference •Used when the patient cannot breathe alone–e.g. Apnoea, Life support, Flail Chest
Explain continuous airway pressure
Useful for neonates, snoring, sleep apnoea, cardiac failure •Some air must remainin the lungs to keep them inflated •Used when the patient cannot breathe alone
Explain partial pressure of gases
Air is a mixture of gases •N2, O2, CO2, H2O •Each gas contributes to net atmospheric pressure •760 mm Hg
Explain Daltons law
Total pressure exerted by a mixture of gases is the sum of the partial pressures of the individual gases P(total) = P1+P2+P3+…..more people make pushing a car easier.
Example in body:pulmonary gas exchange in body…mixture of O2 and CO2 the difference in pressure exerted by gases effect the exchange mechanism.
Pulmonary gas exchange
DeO2Hb → lungs → O2Hb •Partial Pressure in alveoli different to air •Partial Pressure in alveoli different to in the blood/capillaries… Gas exchange occurs along pressure gradients example in foss and fairne/lecture notes.
What is internal respiration
Gas exchange between the capillaries (blood) and the tissues (cells) of the body.
Ratios:
Inspired air: Alveoli of lugs:
Po2 160 mm HG Po2 104 mm HG
Pco2 0.3mm HG Pco2 40mm HG
Blood leaving tissues and entering lungs:
Po2 40 mm HG Blood leaving lungs entering capillaries
Pco2 45 mm HG Po2 100 mm HG
Pco2 40 mm HG
Explain Henrys Law
The amount of a gas that will dissolve in a given type and volume of liquid at a constant temperature is directly proportional to the partial pressure of the gas and it’s solubility constant…
Transport of O2 and CO2 in the blood.
Dissolved in solution (plasma)
Concentration = Partial Pressure
