PULMONARY 02: LUNG MECHANICS 1

Question 1

What is the law that describes how air will flow in and out through airways?

Answer 1

Boyle’s law, and it dictates air will flow according to pressure gradients

Question 2

Inspiration is __(active/passive)__ ; expiration is __(active/passive)

Answer 2

Active; passive

Question 3

What is the most important muscle of respiration?

Answer 3

Diaphragm

Question 4

Aside from the diaphragm, what is the other major set of muscles that aids in inspiration?

Answer 4

External intercostals

Question 5

What are the accessory muscles of expiration?

Answer 5

Internal intercostals

Abdominal muscles

Question 6

Other accessory muscles to inspiration?

Answer 6

Sternocleidomastoid; scalenus (lift of wall of chest)

Question 7

At the end of inspiration and expiration, what is the pressure across the entire system? Why?

Answer 7

Pressure difference across the system is zero, because there is no air flow. Inward recoil of the lung and outward recoil of the chest wall are balanced.

Question 8

Pressures in alveoli relative to outside in inspiration

Answer 8

Alveolar pressure is below atmospheric pressure, leading air to flow in

Question 9

Pressures in alveoli relative to outside during expiration

Answer 9

Alveolar pressure is above atmospheric pressure, therefore air will flow out (along gradient)

Question 10

Boyle’s law

Answer 10

At a fixe temperature, the volume of a gas is inversely proportional to the pressure exerted by the gas

come on, make your gen chem teachers proud by remebering this one

Question 11

If you double the volume of a system, what will happen to the pressure?

Answer 11

The pressure will drop (1/2 original value)

Question 12

If you halve the volume of a system, what will happen to the pressure (at a given number of gas molecules)?

Answer 12

Pressure will double

Question 13

How is the shift in pressures required to change alveolar pressure relative to the outside accomplished?

Answer 13

Muscles changing the volume of the chest cavity

Question 14

The thoracic and abdominal cavities are separated by the ____(muscle)____

Answer 14

diaphragm

Question 15

The lungs are in what body cavity

Answer 15

Thoracic

Question 16

How do the major muscles of inspiration aid in increasing the volume of the chest cavity?

Answer 16

The diaphragm pulls down and enlarges the thoracic cavity in a vertical direction

The external intercostals pull the ribs up and out

Question 17

In deep, forceful inspiration, how do the accessory muscles help?

Answer 17

The scalenus and sternocleidomastoid raise the sternum and elevate the first two ribs, enlarging the portion of the thorax

Nasal muscles are also activated and this provides some MINOR addition of volume

Question 18

Tidal breathing is ____mL air going in/out of lungs

Answer 18

500mL

Question 19

Expiration is mostly a (active/passive) process, and therefore muscles aid in this by:

Answer 19

Passive process:

Diaphragm relaxes, allowing muscle to resume dome shape and reducing volume of chest cavity. Additionally, intercostal muscles relax, and the ribs fall due to gravity. This increase in pressure leads to the lungs deflating and thorax compressing due to natural recoil

Question 20

In forceful expiration, the ___ muscles engaged help in expiration by:

Answer 20

Abdominal muscles help by incresing abdominal pressure, pushing chest cavity up more.

Internal intercostals contract, and flatten the rib cage bby pulling ribs down and out

Question 21

Why do the internal and external intercostals have opposing effects?

Answer 21

They are placed differently on the ribs themselves when compared to the spine

The External intercostals have the most superior rib being the point that has the attachment closest to the ribs. This means that when contracting, the second rib will be ulled up and toward the stable point diagonally. The internal intercostals have the opposite arrangement, with the inferior rib having the stable spinal-adjacent position. This means contraction pulls down diagonally toward the inferior rib

Attached is a picture of the external intercostals.

Question 22

The pleural space is filled with (fluid/air)

Answer 22

FLUID

YOU MUST LUBE THE LUNGS

Question 23

What is the area between the visceral and parietal pleura called?

Answer 23

The pleural space

Question 24

What is the pleura that touches the lungs

Answer 24

visceral pleura

Question 25

what is the pleura that touches the chest cavity

Answer 25

parietal pleura

Question 26

The fluid that fills the intra-pleural space is called what?

Answer 26

Serous fluid it is only 10-20mL

Question 27

Elastic properties of the lung are driven by what two factors?

Answer 27

Surface tension of airways Elastic properties of cells and tissue (elastin (primarily), fibrillin, collagen, etc)

Question 28

According to the chest wall/lung volume relationship, pressures below zero are __(expanding/collapsing)__ and pressures above zero are _(expanding/collapsing)_

Answer 28

Expanding/collapsing

Question 29

At the end of expiration, the chest wall is experiencing a (expanding/collapsing) force, and why?

Answer 29

Expanding. You've forced the system to be really small and it wants to recoil. When you fill the lungs really big at total lung capacity there is a huge pressure now forcing it to collapse.

Question 30

How much of the lung volume is within the expanding forces for the chest wall/pressure within lung volume relationship?

Answer 30

2/3

Question 31

When considering the lungs/lung volume relationship, how often do we see a collapsing force?

Answer 31

ALWAYS | The lungs ALWAYS want to be smaller

Question 32

Describe this image

Answer 32

When we summate the chest wall and lung vs lung volume lines, we get the red line in the middle. The point at which the line crosses zero on the X axis is the functional residual capacity, which is the equilibrium point in lungs where we get to at lung relaxation. This is where the lungs and the chest wall equally try to pull at each other. To get past this point, we require muscles. The collapsing force increases as you move toward total lung capacity.

Question 33

The pleural space, even at rest, is not at "zero" pressure compared to the outside (this would lead to lung collapse). What the pressure relative to the outside? Positive, or negative?

Answer 33

Negative

Question 34

Transmural pressure

Answer 34

Pressure inside relative to outside of a container wall (push pressure)

Question 35

How many pressures do we have to consider when thinking about lung mechanics?

Answer 35

3: Transmural pressure across lung wall (transpulmonary/translung pressure) Transmural pressure across chest wall (transthoracic pressure) Pressure across the entire respiratory system

Question 36

What happens if you puncture the chest wall through the parietal pleura?

Answer 36

This will collapse the lungs, as it will normalize the intrapleural space pressure to the outside. the same problem would happen if you punctured the lung

Question 37

What is the pressure INSIDE THE LUNGS (not pleural space) relative to the outside at rest

Answer 37

Equal

Question 38

What happens to the volume of air in our lungs during inspiration and expiration

Answer 38

Starts at a baseline; as we inhale it increases, as we exhale it decreases

Question 39

What happens to the pressure inside the pleural space as we inspire an expire?

Answer 39

During inspiration, the pressure in the pleural space becomes more negative. this is due to the diaphragm and external intercostals generating a larger space in the chest cavity. During expiration, the opposite occurs, so pressure becomes less negative.

Question 40

What happens to flow of air during inspiration and expiration? Consider air flow relative to air leaving the lungs.

Answer 40

As we breathe in, the flow of air is going into the lungs, so this appears negative on the chart. Then as we stop breathing in, this flow reaches zero. As we breathe out, the air is pushed out, leading to a positive outward flow that diminishes near the end of the breath.

Question 41

during inspiration/expiration what happens to alveolar pressure

Answer 41

At the beginning of a breath we are at equilibrium with the atmosphere. Then we begin to go negative. However, this doesn't follow the same trend as in pleural space pressure because air is flowing inside. Thus by the end of inspiration we equilibrate with the outside. during expiration, the pressure becomes positive as air is pushed passively out through the activity of the chest cavity becoming smaller. Then, as this becomes less pronounced, and pressure equilibrates with the outside again, it returns to zero.

Question 42

What contributes to the sedimentation of medium particles in the bronchioles?

Answer 42

A decrease in air velocity