EXAM III Pulmonary Flashcards
Define minute and alveolar ventilation and equations
Total volume of gases moved in/out of lungs per minute (VE)
Total volume of gases that enter spaces participating in gas exchange/minute (VA)
Define pleural pressure
Pressure of fluid between parietal pleura and visceral pleura
Define alveoli pressure
Pressure of fluid in the alveoli
Define Transpulmonary pressure
Pressure difference b/w alveolar pressure and pleura pressure
What are the two circulations of the lung? Which circulation has a larger compliance?
High Pressure, Low Flow/Volume
thoracic aorta, bronchiole arteries, trachea, bronchial tree, adventitia CT
Low Pressure, High Flow/Volume - larger compliance
pulmonary artery and branches –> alveoli
What are the agents that constrict and dilate pulmonary arterioles?
Epi/NEpi
Angiotensin II
Prostaglandins
What effect does heavy exercise have on blood flow through the lungs? Why does this cause a minimal rise in pulmonary arterial pressure?
Distends capillaries to increase flow rate & increases the amount that are open
Increases pulmonary arterial pressure
What effect does left-sided heart failure have on left atrial pressure? (left side = body; right side = pulmonary)
Increase in blood pressure
Pressure build up in pulmonary circulation
Blood damming in left atrium
What are the four forces that are involved in hydrostatic and colloid forces?
capillary hydrostatic pressure = out
interstitial fluid colloid osmotic pressure = out
Interstitial fluid hydrostatic pressure = in
capillary osmotic pressure = in
Inwards are subtracted from outward force
What are the most common causes of pulmonary edema and at what capillary pressure level does it occurs?
Left-sided heart failure or mitral valve relapse
Damage to pulmonary blood capillary membranes; infections, breathing noxious substances
> 25 mmHg
Mitral valve disease
What are the results of bronchial obstruction and hypoxia in relation to blood flow?
An obstruction causes constriction of vessels that are supplying the poorly ventilated alveoli which is due locally to low alveolar PO2 effect on vessels, a drop in pH due to CO2 accumulation which causes vasoconstriction in pulmonary vessels and vasodilation in other tissues
Hypoxia = increases pressure in pulmonary artery; reduction of blood flow to a portion of the lung
Lowers alveolar PCO2 resulting in constriction of bronchi supplying that portion
(what happens in lungs is opposite of what happens elsewhere)
Define Dalton’s law
The total pressure extered by the mixture of non-reactive gases is equal to the sum/all of the partial pressures of individual gases
Define Boyle’s Law
Boiled water = pressure
Fixed amount of an ideal gas kept at a fixed temp.
Pressure is inversly proportional to Volume
Define Henry’s Law
At constant temp., amount of gas that dissolves in a given volume is directly proportional to the partial pressure of that gas in equilibrium with that liquid
What are the factors that control oxygen concentration in the alveoli?
Rate of absorption of oxygen into the blood
Rate of new oxygen into the lungs (alveolar ventilation)
Why can’t alveolar ventilation increase PO2 above 149 mmHg under normal conditions?
Due to the partial pressure of oxygen in the atm
The functional residual capacity of lungs = 2300ml; only 350 ml of new air is brought into alveoli w/ each normal inspiration and same amount is expired; multiple breaths are required to exchange most of alveolar air (only one 7th is replaced by new atm air)
Must increase oxygen levels in order to increase!!!
What is the structure of the respiratory membrane?
Capillary basement membrane
Epithelial basement membrane of the alveoli
Interstitial fluid not always present
What does the Va/Q ratio refer to?
Alveolar ventilation/blood flow
Define shunted blood
When venous blood passing through pulmonary capillaries does not become oxygenated due to a Va/Q ratio being below normal
Define Physiological Shunt
Wasted blood flow due to blood entering arterial system without passing through ventilated areas, causing PO2 of arterial blood to be less than PO2 of alveolar
Define physiological dead space
Wasted ventilation due to having a greater amount of ventilation with low blood flow
The sum of the wasted ventilation plus the anatomic dead space
What occurs to the Va/Q ratio when there is an airway obstruction?
(mucus plug)
No ventilation but still Perfusion
Va = 0
Blood gas compostion remains unchanged
All areas equilibrate
What occurs to the Va/Q ratio when there is a vascular obstruction?
(pulmonary embolism)
No perfusion; ventilation yes
Va/0 = infinity
No gas exchange, no blood contact = creates a physiological shunt
What are the factors that determine tissue PO2?
Rate of oxygen transported to the tissues
Rate of oxygen consumption by the tissue
