21-3: Mechanics of Breathing Flashcards
pulmonary ventilation
exchange of gasses between the atmosphere and the alveoli of the lungs, depending on pressure differences.
When the pressure inside the lungs is less than atmospheric pressure, air moves ___.
into the lungs
inspiration
the process of breathing in
atmospheric pressure
the pressure exerted by the air (gases) around the body, 750 mmHg at sea level
intrapulmonary pressure
pressure within the alveoli of the lungs; must be less the atmospheric pressure for air to enter lungs
intrapleural pressure
pressure in pleural cavity around the lungs, abt 4 mmHg lower (neg pressure)
transpulmonary pressure
difference between intrapulmonary and intrapleural pressure, keeps lungs from collapsing
Boyle’s Law
when temperature is constant, the pressure of a gas in a closed container varies inversly with the volume of the container. inc V = dec P
The thoracic cavity is the closed container housing the lungs (enclosed by ribs, vertebrae and diaphragm) and the single entrance is the trachea
When the volume of the thorax increases: pressure ___, and air ___.
decreases; moves into lungs
When the volume of the thorax decreases: pressure ___, and air ____.
increases; moves out of lungs
How does the volume of the thorax increase?
contraction of inspiratory muscles (diaphragm and external intercostals)
What is the diaphragm’s role in inspiration?
dome shaped skeletal muscle forming floor of thorax
contraction causes it to pull down, flatten, and lengthen the thorax
What is the role of the external intercostals in inspiration?
muscles between ribs
contraction pulls ribcage up and out, and thoracic cavity widens
Contraction of the inspiratory muscles causes the size of the thorax to ____, intrapulmonary pressure to ___ atmospheric pressure, and air to ___.
increase; drop below; be drawn into lungs
expiration
the process of breathing out
Normal expiration is a ___ process, depending on ___.
passive; natural elasticity of lungs
During expiration, the inspiratory muscles ___, causing: __.
The volume of the thoracic cavity ___, and intrapulmonary pressure is __ atmospheric pressure, causing air to ____.
relax; rib cage to move down and diaphragm move back up
decreases; higher; rush out of lungs
During expiration, intrapulmonary pressure is ___ atmosphiric pressure.
higher than
During inspiration, intrapulmonary pressure is ___ atmospheric pressure.
lower than
Forceful expiration is a(n) ___ process.
active
What muscles are involved in forceful expiration?
abdominal and internal intercostal muscles
During forceful expiration, the ____ muscles ____, ___ the volume of the thoracic cavity.
What effect does this have on the air in the lungs?
abdominal and intercostal muscles contract; further decreasing
more air is forced out of lungs
spirometer
device used to measure the amount of air flushed in and out of hte lungs during breathing
respiratory rate
breaths per minute
tidal volume
amount of air moved into or out of the lungs wiht each normal quiet breath
inspiratory reserve volume
the amount of air that can be inhaled forcibly beyond the tidal volume
inspiratory capacity
the total amount of air that can be inspired after a normal expiration
IC = TV + IRV
expiratory reserve volume
the maximum amount of air that can be forcibly expired beyond tidal volume
vital capacity
the total amount of exchangable air, a maximum expiration following following a maximum inspiration
VC = IRV + TV + ERV
residual volume
amount of air left in lungs after a maximum expiration (to keep them from collapsing)
total lung capacity
the maximum amount of air that the lungs can hold
TLC = IRV + TV + ERV + RV
minute ventilation
the total amount of gas that flows into or out of the respirator tract in one minute
minute ventilation equation
MTV = TV x RR
