PULMONARY 01: FUNCTIONAL ANATOMY

Question 1

Main purposes of the upper airways

Answer 1

Filtration, warmth, and humidity of air

Question 2

Main zones of airways

Answer 2

Conducting zone, respiratory zone

Question 3

Conducting zone is also called “anatomical dead space,” what does this mean?

Answer 3

There is no gas exchange occurring here

Question 4

Bronchi vs bronchioles - which has cartilage?

Answer 4

Bronchi have cartilage, bronchioles do not

Question 5

What is the volume of the anatomical dead space and how does this compare to total lung capacity?

Answer 5

It is about 150mL

Total lung capacity is about 5L

Question 6

What is the volume of the respiratory region?

Answer 6

2.5-3L

Question 7

What is the surface area of the respiratory region

Answer 7

50-100m^2

~750sqft (average apt in chicago area)

Question 8

What is the broncho-pulmonary segment?

Answer 8

The functional anatomical unit

Question 9

What is the respiratory segment

Answer 9

Composed of the respiratory bronchi and alveolar ducts, this is the physiological unit

Question 10

How does the composition of alveoli capillary networks contribute to gas exchange?

Answer 10

The alveoli capillaries are extremely thin which allows for gas diffusion

Question 11

Why don’t alveoli collapse due to Laplace’s law?

Answer 11

Because of surfactant, which reduces surface tension, interdependence (collateral ventilation, mechanical tethering stabilizing alveoli)

Question 12

Law of Laplace

Answer 12

Magnitude of inward directed pressure in a bubble (alveolus) = (2x Surface tension(T))/Radius of alveolus

Question 13

What is the normal conclusion based on the Law of Laplace, regarding the stability of alveoli?

Answer 13

You would typically expect small alveoli to collapse due to small pressure and high tension, and that large bubbles would become over-distended

Question 14

Why do alveoli not collapse (primarily)

Answer 14

Surfactant

Interdependence

Question 15

What produces surfactant?

Answer 15

Type II cells

Question 16

What is the surfactnat

Answer 16

It is a lipoprotein complex (phospholipids, surfactant-associated proteins, neutral lipids)

Question 17

How does surfactant break up surface tension

Answer 17

Smaller alveli are more affected than bigger ones, so it has less impact on larger alveoli. It normalizes inward directed force by breaking up some of that fluid-generated water pressure.

Question 18

What does surfactant allow for as far as filling rates?

Answer 18

It allows for small and large alveoli to fill at similar rates

Question 19

What is interdependence with regard to alveoli?

Answer 19

Mechanical tethering and collateral ventilation supporting the structural integrity of the alveoli

Question 20

What is the mechanical tethering aspect of interdependence?

Answer 20

The tendency to collapse of alveoli is put off by tethering to neighboring alveoli; if one alveoli wants to get smaller (collapse) the others stop it, because they want to get bigger. thus, if one gets smaller, the others provide resistive force.

Question 21

What is the collateral ventilation stability of alveoli? (MLK)

Answer 21

This is the connections of neighboring alveoli. This is done through the MLK system:
M: Martin channels which connect neighboring bronchioles
L: Lambert channels which connect bronchioles to the alveoli that neighbor it
K: Kohn (pores of Kohn) which connect alveoli together

Question 22

What are the two circulatory systems that feed the lungs?

Answer 22

Bronchial (systemic) and pulmonary (deox blood from RV)

Question 23

What is the largest vascular bed in the body?

Answer 23

The pulmonary circulation (the circulation from the RV)

Question 24

What is the role of the lungs in the RAAS system?

Answer 24

The lungs has ACE which will convert Angiotensin I to active Angiotensin II

Question 25

How do our lungs remove inhaled particles?

Answer 25

Change answer to swallowing, mucociliary transport, & macrophages

Question 26

Pathogenic consequences of the mucociliary clearance

Answer 26

Some viruses can use the mucociliary system to their advantage to stabilize and become more virulent

Question 27

How do the cilia in the mucociliary clearance system work?

Answer 27

The cilia are beat back and forth by microtubule and dynein motors to get things moving; basically dynein pulls on microtubules to get them to beat in the right organization.

Question 28

What are the ways we can clear inhaled particles (big picture)? Think about anatomical location and basically what will happen if particles get there. Hint: There are 3 big ones

Answer 28

Nasopharynx (particles can be swallowed)

Bronchi (mucociliary systems transports)

Alveoli (alveolar macrophages engulf particles)

The lymphatics also play a role for the macrophages to fuck off after they’ve done their job

Question 29

Deposition of inhaled material occurs in what 3 ways

Answer 29

Impaction, sedimentation, diffusion

Question 30

Deposition of inhaled material by impaction: Particle size, representative site

Answer 30

Large particles, nasopharynx

Question 31

Deposition of inhaled material via sedimentation; what is the particle size and where is a representative site

Answer 31

Medium particles (1-5um) and this occurs in small airways, such as bronchioles

This is why smokers have a lot of bronchiole problems and get a lot of long term problems

Question 32

Deposition of inhaled material by diffusion: where would this occur and what would the size of the particls be

Answer 32

Alveoli, small particles (<0.1um)

Many small particles will also be exhaled back out

Question 33

Anatomical shunting

Answer 33

Blood from lungs via pulmonary arteries is returned to pulmonary veins without passing through pulmonary capillaries. This bypasses alveolar gas exchange and leads to a slight overall decrease in overall oxygenation of blood going back to heart

Question 34

What creates surface tension in the alveoli?

Answer 34

There is water on the internal surface of the alveoli, which creates surface tension that resists being stretched and reduces surface area.