Intro To The Respiratory System Flashcards
Why do we need a respiratory system?
1) Cells require energy to function, and we need O2 to make that energy
2) Aerobic respiration requires O2 and produces CO2. The atmosphere provides a source of O2, and CO2 can be expelled.
3) Our bodies are too large to rely on simple diffusion of gases from the atmosphere to the tissues.
What functions does the respiratory system have within the body?
- it provides (and ventilates) a specialised surface where gas exchange can take place between the atmosphere and the blood
- it contributes to the acid-base balance in the body (eg. the pH of the blood)
- its used for communication and metabolism
How does oxygen get from the atmosphere to the cells?
1) O2 is inhaled from the atmosphere into the alveoli within the lungs.
2) O2 diffuses from the alveoli into the blood within the pulmonary capillaries.
3) O2 is transported in the blood, predominantly bound to haemoglobin.
4) O2 diffuses into cells/tissues for use in aerobic respiration.
5) CO2 diffuses from the respiring tissues to the blood (the exchange occurs at the lungs).
Why is ventilation of gas exchange structures necessary?
Tissues continually demand O2 and produce CO2.
An adequate concentration gradient between the alveolar air and blood is required for efficient gas exchange (diffusion). Therefore, fresh air is required from the atmosphere to ensure that the alveolar oxygen pressure (PalvO2) is high and the alveolar CO2 pressure (PalvCO2) is low, relative to the blood.
What is the ideal gas law?
It is the equation of state of the hypothetical gas. It helps us model and predict the behaviours of gases.
It’s what helps us understand that gases naturally move from (connected) areas of higher pressure to lower pressure, until an equilibrium is re-established.
PV=nRT
where P is pressure, V is volume, n is the number of moles, R is the gas constant and T is the temperature.
We can manipulate the ideal gas law to produce Boyle’s Law.
Describe Boyle’s Law.
Boyle’s Law states that the pressure of a gas is proportional to the number of has molecules within a given volume.
P ∝ n/v
If the n remaines constant, increasing the volume will decrease the pressure.
Air consists of a mixture of gases which behave in accordance with their partial pressure rather than concentration.
How can we calculate partial pressure?
Partial pressure can be calculated by multiplying the total pressure by the mole fraction.
P gas = (P barometric - P H2O) x n gas
P gas is the partial pressure of the individual constituent gas, P barometric is the atmospheric pressure, P H2O is the water vapour pressure and n gas is the mole fraction.
