Intro to Respiratory Physiology

Question 1

How does gas move across the blood-gas interface?

Answer 1

diffusion

Question 2

What physical factor really determines which way gas will move?

Answer 2

pressure - will move from high pressure to low pressure

Question 3

What is the partial pressure of O2 in the air compared to venous blood? What does this means/

Answer 3

150 mmHg in the air and 40 mmHg in the venous (pulmonary arterial) blood, so O2 will move into the blood

Question 4

Why will carbon dioxide move from blood to air?

Answer 4

partial pressure of CO2 is 46 mmHg in the venous blood but almost 0 mmHg in the air

Question 5

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?

Answer 5

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

Question 6

How is gas movement related to cross sectional area? How about the thickness of the barrier?

Answer 6

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

Question 7

What is the order of the airways starting from the top?

Answer 7

trachea
right and left bronchi
lobar bronchi
segmental bronchi
terminal bronchioles
alveoli

Question 8

What are the conducting airways?

Answer 8

the trachea to the terminal broncholes

they conduct air but are NOT involved in gas exchange

Question 9

What do the conducting airways comprise?

Answer 9

the anatomic dead space - the regions of the lung not exchangin air

Question 10

The anatomic dead space has gas concentrations similar to the atmosphere except for what?

Answer 10

the air is humidifed

Question 11

What is the average size of the anatomic dead space?

Answer 11

about 150 ml

Question 12

What would be a clinical example of an increased dead space?

Answer 12

intubation - basically makes your neck longer

Question 13

What is another name for the respiratory zone?

Answer 13

acinus

Question 14

What parts of the airways make up the respiratory zone?

Answer 14

the respiratory bronchioles have a few occasional alveoli

the alveolar ducts - completely lined with alveoli

Question 15

What initiates airflow into the lungs?

Answer 15

expansion of the thoracic cavity as the diaphragm and intercostals contract

Question 16

How far down into the airways will air flow just based on inspiration? How does it get further?

Answer 16

Goes down to the terminal bronchioles from inspiration

gets to the respiratory bronchioles and avoleoar ducts via diffusion

Question 17

So where would an inhaled particle settle along the airways?

Answer 17

in the terminal bronchioles - won’t get into the respiratory bronchioles or the alveoli because it can’t diffuse there

Question 18

True or false: the lung is not very compliant

Answer 18

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

Question 19

What is the order of blood vessels that blood will travel through in the pulmonary circuit?

Answer 19

pulmonary arteries leave the heart
capillaries
pulmonary veins back to the heart

Question 20

How much time do RBCs spend in the pulmonary capillaries?

Answer 20

less than a second! But they can equilibrate almost completly with alveolar gas in that span of time

Question 21

Why are birds and fish even better at gas exchange than we are?

Answer 21

counter current exchange - air is flowing in the opposite direction as the blood flow - more efficiency

Question 22

True or false: bronchial circulation is from the pulmonary side?

Answer 22

false - it’s from the systemic side (duh - it needs to be oxygenated)

Question 23

WHat is the issue with surface tension in the alveoli based on laplaces law of T=PxR?

Answer 23

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

Question 24

What reduces surface tension and prevents alveolar collapse?

Answer 24

surfactant

Question 25

What are the ways we can keep/move inhaled particles out of our airways?

Answer 25

filtered by the nose

can be moved towards the mouth by a mucous-ciliary elevator

can be engulfed by alveolar macropahges