Intro to Respiratory Physiology Flashcards
How does gas move across the blood-gas interface?
diffusion
What physical factor really determines which way gas will move?
pressure - will move from high pressure to low pressure
What is the partial pressure of O2 in the air compared to venous blood? What does this means/
150 mmHg in the air and 40 mmHg in the venous (pulmonary arterial) blood, so O2 will move into the blood
Why will carbon dioxide move from blood to air?
partial pressure of CO2 is 46 mmHg in the venous blood but almost 0 mmHg in the air
So the air moving into the lungs have 150 mmHg O2 and 0 mmHg CO2. What are the partial pressures of these two gases in the alveoli though? Why?
100 mmHg of O2 and 40 mmHg of CO2
because it’s in the alveoli - some O2 has already gone into the blood and some CO2 has already entered the air
How is gas movement related to cross sectional area? How about the thickness of the barrier?
Directly proportional to the cross sectional area
Inversely proportional to the thickness of the barrier
so you want a large surface area and a thin barrier for gas to diffuse though - this is why we have so many alveoli and why the alveolar walls are less than one micrometer
What is the order of the airways starting from the top?
trachea right and left bronchi lobar bronchi segmental bronchi terminal bronchioles alveoli
What are the conducting airways?
the trachea to the terminal broncholes
they conduct air but are NOT involved in gas exchange
What do the conducting airways comprise?
the anatomic dead space - the regions of the lung not exchangin air
The anatomic dead space has gas concentrations similar to the atmosphere except for what?
the air is humidifed
What is the average size of the anatomic dead space?
about 150 ml
What would be a clinical example of an increased dead space?
intubation - basically makes your neck longer
What is another name for the respiratory zone?
acinus
What parts of the airways make up the respiratory zone?
the respiratory bronchioles have a few occasional alveoli
the alveolar ducts - completely lined with alveoli
What initiates airflow into the lungs?
expansion of the thoracic cavity as the diaphragm and intercostals contract
How far down into the airways will air flow just based on inspiration? How does it get further?
Goes down to the terminal bronchioles from inspiration
gets to the respiratory bronchioles and avoleoar ducts via diffusion
So where would an inhaled particle settle along the airways?
in the terminal bronchioles - won’t get into the respiratory bronchioles or the alveoli because it can’t diffuse there
True or false: the lung is not very compliant
false! it’s super compliant - so you’ll get a big change in volume for only a small change in pressure
the flow rate is about 1 L/sec and is associated with only a 2cmmwater drop in pressure
What is the order of blood vessels that blood will travel through in the pulmonary circuit?
pulmonary arteries leave the heart
capillaries
pulmonary veins back to the heart
How much time do RBCs spend in the pulmonary capillaries?
less than a second! But they can equilibrate almost completly with alveolar gas in that span of time
Why are birds and fish even better at gas exchange than we are?
counter current exchange - air is flowing in the opposite direction as the blood flow - more efficiency
True or false: bronchial circulation is from the pulmonary side?
false - it’s from the systemic side (duh - it needs to be oxygenated)
WHat is the issue with surface tension in the alveoli based on laplaces law of T=PxR?
It basically means small alveoli should want to collapse and give up their air to large alveoli, in which case you’d just get more and more large alveoli until you just had one hue alveoli
What reduces surface tension and prevents alveolar collapse?
surfactant
What are the ways we can keep/move inhaled particles out of our airways?
filtered by the nose
can be moved towards the mouth by a mucous-ciliary elevator
can be engulfed by alveolar macropahges
