Mechanics

Question 1

Result of Muscle Contraction:
descend downward increasing the vertical dimension of the throacic cavity

Answer 1

Diaphragm

Question 2

Result of Muscle Contraction:
Elevate the lower ribs upward and outward, enlarging the thorax in both the front-to-back and side-to-side dimensions

Answer 2

External Intercostals

Question 3

Result of Muscle Contraction:
Raise the sternum and elevate the first two ribs, enlarging the upper portion of the thoracic cavity

Answer 3

scalene and sternocleidomastoid

Question 4

Result of Muscle Contraction:
Maintains patency of the conducting upper airways to reduce airflow resistance

Answer 4

Muscles of the upper respiratory tract

Question 5

The Inspiratory Muscles include:

Answer 5

diaphragm, external intercostals, scalene and sternocleidomastoid and muscles of the upper respiratory tract

Question 6

Result of Muscle COntraction:
Increase the intra-abdominal pressure, which exerts an upward force on the diaphragm to decrease the vertical dimension of the thoracic cavity

Answer 6

abdominal muscles

Question 7

Result of Muscle Contraction:
flatten the thorax by pulling the ribs downward and inward, decreasing the front-to-back and side-to-side dimensions of the thoracic cavity

Answer 7

internal intercostals

Question 8

The expiratory muscles include:

Answer 8

abdominal muscles and internal intercostals

Question 9

Timing of Stimulation to Contract:
Only during active (forced) expiration

Answer 9

abdominal muscles and internal intercostals

Question 10

Timing of Stimulation to Contract:
Only during forced inspiration; accessory inspiratory muscles

Answer 10

Scalene and sternocleidomastoid and muscles of the upper respiratory tract

Question 11

Timing of Stimulation to Contract:
During active inspiration; the primary muscle of inspiration

Answer 11

Diaphragm

Question 12

Timing of Stimulation to Contract:
During active inspiration; play a secondary role to the primary action of the diaphragm

Answer 12

external intercostals

Question 13

Expiration (at rest) to functional residual capacity is ___ due to the elastic recoil of the lungs

Answer 13

passive

Question 14

Expiration is ___ as needed for exercise or beyond FRC

Answer 14

active

Question 15

In a person breathing rhythmically while sleeping, the expiration of tidal volume would be due to
a) contraction of the abdominal muscles
b) elastic recoil of the lung tissue
c) elastic recoil of the chest wall
d) contraction of the diaphragm

Answer 15

b

Question 16

In a person breathing rhythmically while sleeping, the inspiration of tidal volume would be due to
a) contraction of the abdominal muscles
b) elastic recoil of the lung tissue
c) elastic recoil of the chest wall
d) contraction of the diaphragm

Answer 16

d

Question 17

During forced inspiration, which muscle is not contracting
a) diaphragm
b) external intercostal
c) internal intercostal
d) scalene

Answer 17

c

Question 18

Intrapleural, pleural, or intrathoracic pressure

Answer 18

pressure within the pleural cavity exerted outside the lungs within the thoracic cavity; usually less than atmospheric pressure

Question 19

intrapulmonary or alveolar pressure

Answer 19

the pressure within alveoli. bc alveoli communicate with the atmosphere thru conducting airways, air quickly flows down its pressure gradient any time intrapulmonary pressure differs from atmospheric pressure

Question 20

transpulmonary pressure

Answer 20

difference in pressure between the inside and outside of the alveoli; it is equal to intrapulmonary pressure minus the intrapleural pressure

Question 21

Pressures During breathing Cycle:
Start inspiration

Answer 21

Diaphragm contracts
chest volume increases
pleural pressure decreases
alveolar pressure decreases
air flows into lungs
volume of air in lungs increases
pressure equilibrate

Question 22

Pressures During breathing Cycle:
Passive expiration

Answer 22

diaphragm relaxes
chest volume decreases
intrapleural pressure increases
alveolar pressure increases
air flows out of lungs
volume of air in lungs decrease
pressures equilibrate

Question 23

At the start of inspiration, there is a fall in
a) atmospheric pressure
b) intra-alveolar pressure
c) intra-pleural pressure
d) intra-alveolar and intra-pleural pressure

Answer 23

d

Question 24

towards the end of inspiration, there is an increase in
a) atmospheric pressure
b) intra-alveolar pressure
c) intra-pleural pressure
d) intra-alveolar and intra-pleural pressure

Answer 24

b

Question 25

At the end of inspiration, which two pressure are equal?
a) atmospheric & alveolar
b) atmospheric & pleural
c) alveolar & pleural
d) atmospheric, alveolar & pleural

Answer 25

a

Question 26

Which of the following events occurs first to start the normal sequence of inspiration?
a) intrapulmonary pressure decreases
b) intrapleural pressure becomes more negative
c) air flows into the lungs, causing an increase in intrapulmonary pressure
d) diaphragm contracts

Answer 26

d

Question 27

Elastic Properties of the Lung:
Elastin primarily contributes to the elasticity
Collagen limits ___

Answer 27

over-expansion

Question 28

Lung Compliance:
Pulmonary Fibrosis

Answer 28

involves an increase in fibrous material within the lung interstitium. causes the lungs to stiffen which decreases lung compliance; when the elastic recoil fo the lung is increased, normal changes in transpulmonary pressure produce smaller than normal changes in lung volume; lung compliance is also decreased with alveolar edema or if pulmonary venous pressure is increased; these conditions inhibition proper inflation of alveoli

Question 29

Lung compliance:
Emphysema

Answer 29

degradation of the elastin and collagen framework of the lung parenchyma; results from excessive release of destructive enzymes such as trypsin from alveolar macrophages in response to chronic exposure to cigarette smoke or other inhaled chemical irritants; emphysema markedly decreases the elastic recoil of the lung, thereby increasing the compliance of the lung; reduction of radial traction that keeps small airways stretched open –> leads to airway collapse and increase in airway resistance during expiration

Question 30

Elastic recoil v radial traction

Answer 30

elastic recoil and radial traction are both caused by the effects of elastin on lung tissue; the elastin that surrounded a single airways produces radial traction that keeps the airway open; overall, the elastin in the lung works to produce inward recoil

Question 31

Surface tension:
the air-liquid interface exists in the alveoli

Answer 31

the interface generates surface tension that behaves like a thin bubble that is prone towards collapse and resists the expansion of the alveoli during inspiration
- two alveoli of unequal sizes but having the same surface tension are joined together by same terminal airway, the alveolus with a small radius will have a higher pressure and will empty its air into larger alveolus

Question 32

Surfactant is a…

Answer 32

lipid protein complex that is produced by type II alveolar cells; it contains hydrophobic and hydrophilic regions that allow it to incorporate into the air-liquid interface

Question 33

Surfactant increases the ___ of the lung by reducing ___ that would draw fluid to the alveolar surface

Answer 33

compliance; surface tension

Question 34

The second property of surfactant is that as the surface area of a surfactant film is increased…

Answer 34

the surface tension increases

Question 35

Surfactant Medical Consideration:
Type II alveolar cells produce surfactant at ___ gestation

Answer 35

30 weeks; infants > 10 weeks premature may develop respiratory distress syndrome