Mechanics Flashcards
Result of Muscle Contraction:
descend downward increasing the vertical dimension of the throacic cavity
Diaphragm
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
External Intercostals
Result of Muscle Contraction:
Raise the sternum and elevate the first two ribs, enlarging the upper portion of the thoracic cavity
scalene and sternocleidomastoid
Result of Muscle Contraction:
Maintains patency of the conducting upper airways to reduce airflow resistance
Muscles of the upper respiratory tract
The Inspiratory Muscles include:
diaphragm, external intercostals, scalene and sternocleidomastoid and muscles of the upper respiratory tract
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
abdominal muscles
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
internal intercostals
The expiratory muscles include:
abdominal muscles and internal intercostals
Timing of Stimulation to Contract:
Only during active (forced) expiration
abdominal muscles and internal intercostals
Timing of Stimulation to Contract:
Only during forced inspiration; accessory inspiratory muscles
Scalene and sternocleidomastoid and muscles of the upper respiratory tract
Timing of Stimulation to Contract:
During active inspiration; the primary muscle of inspiration
Diaphragm
Timing of Stimulation to Contract:
During active inspiration; play a secondary role to the primary action of the diaphragm
external intercostals
Expiration (at rest) to functional residual capacity is ___ due to the elastic recoil of the lungs
passive
Expiration is ___ as needed for exercise or beyond FRC
active
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
b
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
d
During forced inspiration, which muscle is not contracting
a) diaphragm
b) external intercostal
c) internal intercostal
d) scalene
c
Intrapleural, pleural, or intrathoracic pressure
pressure within the pleural cavity exerted outside the lungs within the thoracic cavity; usually less than atmospheric pressure
intrapulmonary or alveolar pressure
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
transpulmonary pressure
difference in pressure between the inside and outside of the alveoli; it is equal to intrapulmonary pressure minus the intrapleural pressure
Pressures During breathing Cycle:
Start inspiration
Diaphragm contracts
chest volume increases
pleural pressure decreases
alveolar pressure decreases
air flows into lungs
volume of air in lungs increases
pressure equilibrate
Pressures During breathing Cycle:
Passive expiration
diaphragm relaxes
chest volume decreases
intrapleural pressure increases
alveolar pressure increases
air flows out of lungs
volume of air in lungs decrease
pressures equilibrate
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
d
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
b