Mechanics of Breathing Flashcards
What is respiration simply put?
the exchange of gases between the atmosphere, blood, and body
What are the 3 main steps of respiration?
Pulmonary ventilation
External respiration
Internal Respiration
Simply explain pulmonary ventilation
“Breathing”
inhalation and exhalation of air with exchange of air between the atmosphere and the air spaces of the lungs
Simply explain external respiration
Pulmonary (lung and blood)
exchange of gases between the lung spaces and blood in the pulmonary capillaries across the respiratory membrane
blood gains O2 and loses CO2
Simply explain internal respiration
Tissue (blood–>tissues)
exchange of gases between capillary blood (cellular aerobic respiration)
The closed compartment housing the lungs and heart bound at the neck by muscles and connective tissue
Thorax … aka the chest
the dome-shaped sheet of skeletal muscle that separates the thorax from the abdomen
Diaphragm
What is the thoracic wall formed by?
the spinal column, ribs, sternum, and intercostal muscles
Each lung is surrounded by a closed sac called
pleural sac
the pleural surface coating the lung is called
visceral pleura
the outer layer of the pleural cavity that lines the interior thoracic wall and diaphragm is
parietal pleura
the two layers of pleura are separated by
intrapleural fluid
what is the purpose of intrapleural fluid
lubricates the pleural surfaces so they can slide past eachother without being separated easily. This prevents friction with breathing.
think of two glass slides with water in between
What are the primary muscles used to accomplish breathing
diaphragm and external intercostals
What are the big 4 accessory muscles used to accomplish breathing
internal intercostals
abdominal (rectus abdominis, obliques)
SCM
Scaleness (anterior, middle, posterior)
What are the other accessory muscles used for breathing
pectoralis (major, minor)
latissimus dorsi
serratus anterior
Movement of the diaphragm accounts for __% of change in intrathoracic volume during quiet inspiration
75%
where is the diaphragm attached? and what does it arch over?
around the bottom of the thoracic cage
liver
The diaphragm moves _________ like a piston when it contracts
downward
which muscle of inspiration runs obliquely downward and forward from rib to rib?
External intercostal muscles
What do external intercostal muscles do whenn they contract in inspiration?
elevate lower ribs when they contract
this pushes the sternum outward
and increases AP diameter of the chest
Where do the phrenic nerves innervating the diaphragm arise from?
cervical segments 3-5
Do you need both the diaphragm and the external intercostals to maintain adequate ventilation at rest
No, you can ventilate with only one, but you do best with both.
Which accessory inspiratory muscles help elevate the thoracic cage during deep labored breathing (exercising)
Scalene and SCM
Which muscles of expiration pass obliquely downward and posteriorly from rib to rib, pulling the ribcage downward when they contract?
Internal intercostals
What does the contraction of internal intercostals and pulling of the ribcage downward result in?
decrease intrathoracic volume and forced expiration
Which abdominal muscles aid in expiration by pulling the ribcage downward and inward?
rectus abdominus
internal and external obliques
Contraction of the abdominal muscles ________ intrabdominal pressure which pushes the diaphragm ________
increases
upward
Are any muscles required for expiration?
No, expiration is passive unless it is forced expiration which is when you see the use of these muscles
_______ and ________ constistute one respiratory cycle
an inspiration and expiration
What is the flow of air between the atmosphere and the lungs driven by?
presence of a pressure difference
Air moves into the lungs when the pressure inside the lungs is _____ than that of the atmosphere, which is _________
less
inspiration
Air leaves the lungs when the pressure inside the lungs is ________ than that of the atmosphere, which is ________
greater
expiration
During inspiration, the lungs must expand which ______ lung volume and _________ lung pressure to lower than atmospheric pressure
increases lung volume
decreases lung pressure
Inspiration _______ the alveoli and causes ______ of the principal muscles (diaphragm and external intercostals) and with deep inspiration, accessory muscles
expands the alveoli and causes contraction
___________ is dependent of elastic fiber recoil and inwards pull of surface tension due to alveoli fluid
expiration
When does expiration begin
when the muscles of inhalation relaxes
During expiration, lung volume __________ and alveolar pressure ___________ to higher than that of atmospheric pressure, which causes the air to flow outward
lung volume decreases
and alveoli pressure increases
What happens with labored breathing?
abdominal and internal intercostal muscles contract which moves the inferior ribs downward, contracts the abdominal viscera and forces the diaphragm up (superiorly)
Contraction of inspiratory muscles increases intrathoracic volume. What does this mean?
pressure in the airway becomes negative and air flows down INTO lungs
The lung recoil pulls chest back into expiratory position and pressures balance out. What does this mean
Pressure in the airway becomes positive and air flows OUT of the lungs
Lung capacities contain 2 or more ________
volumes
Where are volumes and capacities recorded on
diagnostic spirometry
What is diagnostic spirometry used to assess
a patients lung function in comparison with normal population
or
comparing measurements from the same patient throughout therapy
The amount of air that moves into the lungs with each inspiration during quiet breathing (normal breathing)
or the amount that moves out with expiration
Tidal volume (TV)
Normal value of TV
500-700 mL of air
the air inspired with MAXIML inspiratory effort in excess of the tidal volume
“breathe in as long and as deeply as you can”
Inspiratory reserve volume (IRV)
Normal value you IRV
2L of air
The volume of air expelled by an ACTIVE expiratory effort AFTER PASSIVE EXPIRATION
Expiratory reserve volume (ERV)
The air left in lungs after MAXIMAL expiratory effort
Residual Volume (RV)
Normal value of RV
1.3 L of air