respiration Flashcards
4 variables for respiratory physiology
volume, pressure, temperature, motion
what is boyle’s law
P is inversely proportional to 1/V
what is the partial pressure of saturated water vapour at 37ºc
47mmHg
what does it mean when you say inspired air is saturated with water vapor
water vapor is diluting the gases
Pressure and % of O2 in inspired gas
21kPa, 21%
partial pressure of O2 when it reaches the alveoli
19.9kPa
what is Daltons law of partial pressure
pressure exerted by each gas in a mixture of gases is independent of the other gases present
what is the PO2 in arterial blood
13.3kPa
what is the PCO2 in arterial blood
5.3kPa
what is the PO2 in the alveoli
13.3 kPa
what is the PCO2 in the alveoli
5.3kPa
what is the PO2 in venous blood
5.3kPa
what is the PCO2 in venous blood
6.0kPa
what happens during inspiration
- ribcage expands
- lungs stretch
- diaphragm moves downwards
- alveolar pressure reduced
- air drawn in
what happens during in expiration
- rib cage contracts
- lungs contract
- diaphragm moves up
- alveolar pressure increased
- air pushed out
what is PVR
pulmonary ventilation rate
PVR equation
respiration rate x tidal vol
what is the average PVR during rest
6l/min
what is the average PVR during exercise
120l/min
what does AVR mean
alveolar ventilation rate
what is AVR
the actual amount of air reaching the alveoli, to calculate it you need to allow for the ‘wasted’ ventilation of dead spaces
what is perfusion (Q)
deoxygenated blood passes through the lungs and becomes re-oxygenated
what is the ventilation perfusion ratio (VA/Q)
a ratio of alveolar ventilation to blood flow
ventilation-perfusion ratio in dead space
1.normal ventilation but no perfusion
2. no capacity to carry O2 away or bring CO2 to alveoli
3. No gas exchange between the alveoli and the blood so alveoli equilibrates with atmosphere
ventilation-perfusion ratio in shunt
- no ventilation, normal perfusion
- No new O2 in system
- alveoli equilibrates with venous blood
what is lung compliance like at high pressure
low as lung is stiffer
what part of lung is more compliant, base or apex
base
what ensues compliance
elastic recoil
how much lung compliance is healthy
high