Lecture 26: Mechanics of Breathing

Question 1

What are the inspiratory muscles (4)?

Answer 1

-Diaphragm
-External Intercostals
-Scalene/Sternocleidomastoid
-Muscles of Upper Respiratory Tract

Question 2

What are the expiratory muscles?

Answer 2

-Abdominal
-Internal Intercostals

Question 3

What is the importance of the negative interpleural pressure?

Answer 3

The negative interpleural pressure keeps the LUNGS pulled against the PARIETAL PLEURA of the chest cavity

Question 4

How are changes in intrathoracic volumes produced during the respiratory cycle?

Answer 4

Respiratory muscles change intrathoracic volume, which changes the pressure, which changes the airflow

Question 5

Why is expiration a passive process during quiet breathing?

Answer 5

Recoil of lungs requires no muscular contractions

Question 6

When atmospheric pressure is equal to alveolar pressure, as at the end of expiration, what happens?

Answer 6

No airflow

Question 7

What causes airflow to go in during inspiration?

Answer 7

The atmospheric pressure is greater than the alveolar pressure (in other words: there’s a large transpulmonary pressure gradient)

Question 8

How does the intrapleural pressure change between during inspiration and at the end of expiration?

Answer 8

During inspiration: IPP is negative
End of expiration: IPP is less negative

Question 9

Under what three conditions does expiration become an active process?

Answer 9

1) Exercise
2) Forced Expiration
3) Hyperventilation

Question 10

How is volume and pressure impact by inhaling vs. exhaling?

Answer 10

Inhaling: Increase volume, decrease pressure
Exhale: Decrease volume, increase pressure

Question 11

How are Intrapleural pressure, Intrapulmonary pressure, and volume of breath affected by inspiration vs Expiration?

Answer 11

Inspiration: Decrease IPP pressures, increase volume
Expiration: Increase IPP pressures, decrease volume

Question 12

Which inspiratory muscle increase the vertical dimension if the thoracic cavity and increases the transverse diameter of the thorax?

Answer 12

Diaphragm

Question 13

What is the primary muscle of respiratory during quiet breathing?

Answer 13

Diaphragm

Question 14

What inspiratory muscle optimizes the inspiratory actions of the diaphragm?

Answer 14

External intercostals

Question 15

Which inspiratory muscles increase thoracic volume?

Answer 15

S/S

Question 16

Which inspiratory muscles decrease airflow resistance

Answer 16

Muscles of the upper respiratory tract

Question 17

Which expiratory muscles decrease thoracic volume?

Answer 17

Internal Intercostals

Question 18

Which muscles increase intraabdominal pressure?

Answer 18

Abdominal muscles

Question 19

Which two inspiratory muscle contracts during active inspiration only?

Answer 19

Diaphragm and external intercostals

Question 20

___ ___ is the pressure within the alveoli

Answer 20

Intrapulmonary/Alveolar Pressure

Question 21

____ ____ is the difference in pressure between inside and outside of alveoli

Answer 21

Transpulmonary pressure

Question 22

How do you calculate transpulmonary pressure?

Answer 22

TPP = Intrapulmonary pressure - Intrapleural Pressure

Question 23

Intrapleural/Pleural/Intrathoracic pressure is usually ___ than ATM pressure

Answer 23

less

Question 24

While elastin fibers can be stretched, collagen fibers resist ___

Answer 24

stretch

Question 25

How does increase in elastic lung recoil affect lung compliance and ease/difficulty of lung inflation?

Answer 25

More recoil means less lung compliance and more difficulty inflating lung

Question 26

Both elastic recoil and radial tension are caused by the effect of ___ on lung tissue

Answer 26

Elastin

Question 27

In pulmonary fibrosis, elastic recoil decrease and compliance increases. As a result, normal inspiratory changes in transpulmonary pressure lead to ___ changes in lung volume

Answer 27

larger

Question 28

If elastin is destroyed, radial tension is ___ and airway ___

Answer 28

reduced; collapses

Question 29

In emphysema, you have __ lung volume and ___ transpulmonary pressure

Answer 29

high; low

Question 30

In pulmonary fibrosis, you have low lung volume and high _____

Answer 30

transpulmonary pressure

Question 31

As one ages, their elastic recoil ___ and compliance ___

Answer 31

decrease; increases

Question 32

The air-liquid interface on the alveoli generates _____

Answer 32

surface tension

Question 33

The thin bubble on alveoli is prone to collapse and resists expansion of alveoli during ___

Answer 33

inspiration

Question 34

According to Laplace's Law, smaller surfaces have __ pressures. Therefore, if two alveoli of unequal sizes but same surface tension are joined via a terminal airway, what will occur?

Answer 34

higher -The alveoli with smaller radius will have greater pressure. Therefore: it will dump its air into larger alveolus

Question 35

How does surfactant affect surface tension and lung compliance?

Answer 35

Surfactant decreases surface tension and increases lung compliance

Question 36

How does surfactant minimize fluid accumulation?

Answer 36

Decreasing alveolar surface tension

Question 37

In Respiratory Distress Syndrome, the production of fetal ___ is delayed. As a result lung compliance is ___

Answer 37

surfactant; decreased

Question 38

A portion of lung elastic recoil is due to the surface tension made by _____ air-liquid

Answer 38

alveolar

Question 39

As the surface area of surfactant increases, so does the _______

Answer 39

surface tension

Question 40

What helps prevent alveolar collapse?

Answer 40

Surfactant

Question 41

In interconnected alveoli, the tendency for one alveolus to reduce/increase its volume is opposed by the adjacent alveoli. If an alveoli starts to collapse, the physical forces exerted by the other surrounding alveoli will tend to prevent this collapse. Alternatively, if one alveolus starts to overinflate, the surrounding alveoli will help prevent this overinflation. What is this called?

Answer 41

Interdependence

Question 42

Functional residual capacity is when passive INWARD recoil of the lung (PL) and the passive OUTWARD recoil of the chest wall are ___, but ___

Answer 42

equal, but opposite

Question 43

At volumes above FRC, the net recoil pressure of the respiratory system favors a ___ in lung volume

Answer 43

decrease

Question 44

At lung volumes below FRC, net recoil pressure of the respiratory system favors an __ in lung volume

Answer 44

increase

Question 45

Lung volumes BELOW FRC can only be maintained by the actions of the muscle of ____ while lung volumes above FRC can only be maintained by the actions of muscle of ____

Answer 45

expiration; inspiration

Question 46

If intrapleural pressure is raised to atmospheric pressure, such as during a puncture pneumothorax, the unopposed lung tissue will recoil ___, while the unopposed chest wall will spring ___

Answer 46

inward; outward

Question 47

During a pneumothorax, the interpleural pressure becomes the same as __. What occurs as a result?

Answer 47

Atmospheric pressure. Result: lung collapses inward and chest wall springs outward