Unit 2 Lecture 12 Flashcards
Define pulmonary ventilation
The alternating flow of air into and out of the lungs
What are the 2 types of respiratory muscles?
- Inspiratory muscles
- expiratory muscles
Function of inspiratory muscles
Expand the rib cage during inspiration and drive airflow into the lungs
Function of expiratory muscles
Depress the rib cage and force air out of the lungs
What is the skeletal portion of the thorax?
Thoracic cage
What bones make up the thoracic cage?
Ribs, costal cartilages, thoracic vertebrae, and sternum
What is respiratory mechanics?
The study of how the respiratory muscles move the rib cage
What does the “respiratory pump” refer to?
The respiratory muscles, rib cage, pleural membranes, and lung elastic tissues
What are the 4 inspiratory muscles?
- Diaphragm
- External intercostal muscles
- sternocleidomastoid
- scalenes
What is the primary inspiratory muscle?
diaphragm
What is the function of the external intercostal muscle?
moves ribs UP and OUT -> expanding the rib cage
What is the function of the sternocleidomastoid
elevates the sternum
What is the function of the scalenes
elevates the top two ribs
What are the 5 expiratory muscles?
- internal intercostals
- External obliques
- internal obliques
- transversus abdominis
- rectus abdominis
What are the oblique and ab muscles called
abdominal muscles
What is the function of the internal intercostals?
pull ribs DOWN and IN -> reducing the diameter of the rib cage
What is the function of the abdominal muscles?
Depresses the lower ribs and elevates the diaphragm by increasing abdominal pressure
What do both the internal intercostals and the abdominal muscles do?
they reduce the thoracic cavity volume to force air out of lungs
What is Boyle’s gas law
*At a constant temperature
The PRESSURE exerted by a gas is INVERSE to the VOLUME of gas
What happens during inhalation?
Throacic cavity increases in size and volume of lungs expands
What muscles contract during quiet, normal inhalation?
Diaphragm and external intercostals
What muscles contract during labored inhalation?
Diaphragm, external intercostals
AND
Sternocleidomastoid, scalenes, and pectoralis minor
What happens to the pressure during inhalation?
Pressure decreases
What happens during exhalation
thoracic cavity decreases in size and lungs recoil
What muscles RELAX during quiet, normal exhalation?
diaphragm and external intercostals
What muscles contract during forceful exhalation?
abdominal and internal intercostal muscles
What happens to pressure during exhalation?
pressure increase
Which way do lungs move physically?
lung tissue rapidly collapses inward
Which way does the chest wall move?
springs outward
What happens to the recoil forces and respiratory muscles between breaths?
recoil forces are equal and respiratory muscles are at rest
Define intra-pleural pressure (Pip)
the fluid pressure in the pleural cavity which surrounds the lungs
Define intra-alveolar pressure (Palv)
the air pressure inside the alveoli
Which pressure is higher? Intra-pleural or intra-alveolar pressure?
Intra-alveolar pressure
Define transpulmonary pressure (Ptp)
distending pressure exerted on the lungs
How do you calculated transpulmonary pressure
Alveolar pressure - pleural pressure
Ptp = Palv - Pip
What happens to pressure during inspiration and expiration
Inspiration: pressure decreases
Expiration: pressure increases
What is the Pip, Palv and Ptp at rest?
Palv = 760 mmHg
Pip = 756 mmHg
Ptp = 4 mmHg
What is the Pip, Palv and Ptp during inhalation?
Palv = 758 mmHg
Pip = 754 mmHg
Ptp = 4 mmHg
What is the Pip, Palv and Ptp during exhalation?
Palv = 762 mmHg
Pip = 756 mmHg
Ptp = 6 mmHg
What is the Pip, Palv and Ptp during a tidal breath?
Palv = 760 mmHg
Pip = 754 mmHg
Ptp = 6 mmHg
Define end-expiratory lung volume
The volume of gas that remains in the lungs at the end of expiration
What is another name for end-expiratory lung volume?
Functional residual capacity
what value is the end-expiratory lung volume?
2 liters
What is the alveolar pressure between breaths?
0 mmHg
What is the intra-pleual pressure between breaths?
< -2
What is a spirogram?
a tool that measures respiration
What is tidal volume
the amount of air the moves in and out of your lungs at rest
What is inspiratory reserve volume?
the amount of air we breath in (above tidal volume) during forced inspiration
What is inspiratory capacity?
inspiratory reserve + tidal volume = total amount we breath IN
What is expiratory reserve
the amount of air we breath out below tidal volume
What is vital capacity?
the amount of air we breath IN AND OUT during labored breathing
What is residual volume
the amount of air that stays in the lungs that we DO NOT breath out
What is functional residual capacity (FRC)
expiratory reserve volume + residual volume = total amount of air that could potentially be exhaled
what is the total lung capacity
the TOTAL amount of air lungs can hold between both inspiration and expiration
define lung compliance
the ease at which the lungs can be inflated
What does emphysema do?
increases lung compliance and raises FRC
What does fibrosis do?
decreases lung compliance and decreases FRC
What is dead space?
of all the air that is inhaled, the air that remains in the upper respiratory system (larynx, trachea, bronchi) where no gas exchange occurs is the “dead space”
Define pulmonary ventilation
a measure of the rate of lung ventiation
what is the formula for pulmonary ventilation
= tidal volume X breathing frequency (beats/min)
Define alveolar ventilation
a measure of the rate at which air actually ventilates the alveoli
what is the formula for alveolar ventilation?
(tidal volume - dead space) X breathing frequency
What does a large FRC mean?
labored breathing
What does a small FRC mean?
large fluctuations in O2 and CO2
What is the formula for lung compliance?
Complience = Change in Volume / Change in Transpulmonary pressure (Ptp)
What value is a normal tidal breath?
500 mL
How many mL of tidal breath reaches alveolar air?
350 mL
How many mL of tidal breath is left in dead space?
150 mL
