Flashcards in Ventilatory system Deck (89)
What component is similar to saline in the lungs that reduce surface tension and improve the ventilatory efficiency?
Surfactant contains what three components secreted by what cells?
-produced by type II alveolar cells.
What is the equation for surface tension on the pressure?
pressure= 2* surface tension/ alveolar radius
By how much does surfactant reduce the surface tension in the lungs?
-reduces by 4.5 times.
What cells, muscles and cartilage are in the trachea?
-pseudostratified ciliated columnar with goblet cells
What are the high pressure/ low flow areas?
thoracic aorta, bronchial arteries, trachea, bronchial tree, adventitia, CT
What are the low pressure/ high flow areas of the lungs?
pulmonary artery and branches to the alveoli
What is the pressure gradient in the pulmonary system?
There is 9% of total blood volume of the body in the lung, where 70mL is in the pulmonary calillaries
What happens if the left side of teh heart were to undergo a failure?
-will increase pulmonary circulation, and BP
-there will be little effect in the systemic, due to the vast amount of fluid in that system
2% of the blood in the systemic arteries is blood that bypasses the pulmonary capillaries, and therefore contains less oxygen per deciliter than blood in equilibrium with alveolar air.
Where does the blood in the physiologic shunt come from?
-this blood is supplied from the lung parenchyma and the left side of the heart
What component contributes to the fact that arteriole blood has less oxygen per liter than in the alveolar capillaries?
-the physiologic shunt
When oxygen concentration is at 73mmHg or lower what happens to the vasculature in the lungs?
-blood vessels constrict by unknown method
-the poorly ventilated alveoli increase the blood to higher functioning alveoli
What are the different zones of blood flow to the lungs and what can affect this distribution?
-zone 1: when standing there is no blood flow, and alveolar pressure is higher than capillary pressure (pathological)
-Zone 2: intermittent flow only during systole
-Zone 3: continuous blood flow
In a normal individual what type of zone can the lungs be divided into while standing?
-apices have zone 2, and lower 2/3 will be a zone 3.
-strenuous exercise can convert all lobes/sections into zone 3
What happens when one lungs blood supply is obstructed and what feature contributes to allow this?
-unobstructed lung increases blood flow 2x
-this is due to passive dilation based on high level of capacitance of the pulmonary vessels
What hormones constrict the pulmonary arterioles?
What agents help dilate the pulmonary arterioles?
What agents cause venule constriction of the pulmonary system?
-E coli endotoxin
The sympathetic vasoconstrictor nerve fibers outflow from the cervical sympathetic ganglia and have what effect on vasculature?
-this decreases the pulmonary blood flow by 30% and mobilizes the blood from the pulmonary reserve to restore blood flow
What happens to allow for increased blood flow through the pulmonary system during exercise?
-opening of previously closed capillaries
-distension of the capillaries
--overall this prevents large increases of pressure in the alveolar capillaries
What are the benefits for the heart of opening new alveolar capillaries and improving there distensibility?
-prevents increased afterload of the heart, and therefore preventing pulmonary edema.
What is the normal left atrial pressure?
If the left atrial pressure is 40-50 mmHg, what is likely to occur?
left sided heart failure
An increase of 8mmHg in the left atria, is enough to cause what effect?
-increase the pulmonary arterial pressure
The pulmonary capillaries are leaky to protein molecules and contribute to what type of colloid osmotic pressure difference when compared to the peripheral tissue?
-the pulmonary interstitial tissue is 2 times higher than peripheral due to higher levels of colloid osmotic pressure
When does pulmonary edema occur within a matter of minutes that the lymphatic vessel are unable to compensate for?
- left sided heart failure or mitral valve disease
-damage to pulmonary blood capillary membranes
What happens when capillary pressure remains chronically elevated for 2 or more weeks?
-the compensatory mechanisms have time to adjust and prevent death.
-acute mechanisms will not be able to compensate as well.