Flashcards in Ventilatory system Deck (89)
Pleural effusion is also know as?
lung collapse when pleural space pressure elevates above -4mmHg
True or False:
Hypoxia increases pressure in the pulmonary artery which is possibly due to release of prostaglandin.
If blood flow to a section of the lung, what are the following effects that will occur?
-alveolar PCO2 is decreased
-this causes constriction of the bronchi to that section of the lung
What are the main components of air?
0.03% Carbon Dioxide
What are is the only gas that exists in equilibrium between the atmosphere and the alveoli?
The total pressure exerted by the mixture of non-reactive gasses is equal to the sum of the partial pressures of individual gasses?
Pressure and Volume are inversely proportional when an ideal gas is kept at a constant amount and constant temperature.
What contributes to the drop of gas concentrations in the alveoli compared to the atmosphere?
the alveoli contain water vapor and offset the 'equilibrium' between atmosphere and alveolar gas concentration
At constant temperature, the amount of a given gas dissolves in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid.
What is the ideal gas law?
R= gas constant
T= temperature in Kelvin
Henry's Law is really mostly concerned with the solubility coefficient, which contributes to the ability of the gas to diffuse when it is dissolved in a liquid.
Why will carbon dioxide exert less partial pressure than oxygen?
-carbon dioxide has a higher solubility and will therefore have a lower exertion of partial pressure
The functional residual capacity of the lungs on average is 2300mL, and only has how much air inspired and expired?
350mL of air is brought into the alveoli
What controls the oxygen concentration in the alveoli and its partial pressure?
-rate of absorption of oxygen into the blood
-rate of new oxygen that enters into the lungs
Why will alveolar ventilation not increase above 149mmHg?
The highest amount of oxygen partial pressure is 149mmHg in the atmosphere. Therefore it is the maxmimum amount that could be absorbed
What is the partial pressure of carbon dioxide concentration in the alveoli controlled by?
-if excretion increases in tissues then PCO2 increases
-PCO2 decreases as ventilation rate increases
How thick should a membrane have to be in order to infere with gas exchange rates?
2-3X the normal thickness based on factors like edema, or fibrosis
What is the primary reason people with COPD has poor gas exchange?
Membrane thickness has increased 2-3X the normal thickness
What is Va/Q ratio?
-alveolar ventilation/ blood flow
What is the normal range for Va/Q?
Va/Q= 0.8= 4/5
Where in the capillary system is gas exchange considered complete?
- initial third of the capillary
If there is a pulmonary obstruction what happens to the Va/Q ratio?
-becomes 0 as Va=0 and therefore the blood gas composition remains the same. No gradient being created to drive exchange of gases
What happens to the Va/Q when there is a vascular obstruction like an embolism?
-Va/Q= infinity as Q=0
- this prevents gas exchange, as no blood can contact the gases
-this is considered a physiological shunt
With a vascular obstruction what happens to the alveolar partial pressures of CO2 and O2?
- PCO2= 0.0
- PO2 =149
During normal alveolar perfusion PCO2 and PO2 are able to reach what levels?
What is the best way to describe shunted blood?
-a certain amount of venous blood in the pulmonary capillaries that does not get oxygenated, normally occurring when Va/Q is below normal (0.8)
The thin descending loop of henle is highly permeable to which components?
Aldosterone is important for sodium reabsorption and potassium secretion, what does it target to do so?