chapter 3 Flashcards
The Goal of Respiration
Oxygenation of blood
Elimination of carbon dioxide, waste products
types of inspiration
Quiet inspiration
Active (forced) inspiration
Types of expiration
Passive expiration
Active/forced expiration
Passive expiration
System is restored to a resting position after respiration
Driven by forces of elasticity and gravity
Active/forced expiration
Muscular effort enhances act of expiration Abdomen is compressed Muscles reduce size of thorax Rib cage is pulled down Air leaves the lungs
How do Lung and abdominal elasticity help with?
Lung and abdominal elasticity help to account for the recoil of the lungs upon inspiration (again recall the natural tendency of object’s to re-establish equilibrium
How does gravity help in expiration?
Gravity also helps to pull ribs and abdominal viscera down when we are breathing while standing (and in certain other positions
What are the lungs?
The lungs are elastic porous tissue (sponge-like) and are naturally stretched out in adults whereby they are larger than their natural resting position
Why are the lungs stretched out in adults?
the volume of the ribcage relative to the volume of the lungs
the linking between the visceral and parietal pleurae
pleural linkage
The thorax grows more than the lungs. Since the parietal and visceral pleurae are continuous, when the thorax grows the parietal pleurae pulls the visceral thus stretching the lungs
Children Lungs
Children’s lungs completely fill the thorax and develop slower than the ribcage
Children typically breathe 2-3x as often as adults
# of alveoli and surface area increase with age
Spirometer
used to measure respiration
Rate of air flow in respiration
Volume
Lung capacities
Manometer
Force produced when blowing in a tube
Pressure
Spirometers measure
lung volume
Lung volume is measured as the amount of water displaced
Lung capacities
U-tube manometers measure
pressure
Pressure utilized is measured as the distance that water/liquid has been displaced
Force produced when blowing in a tube
4 stages of gas exchange
Ventilation
Distribution
Perfusion
Diffusion
Ventilation:
actual movement of air in the respiratory pathways over unit time
Distribution:
division of air to all of the alveoli
Perfusion
migration of oxygen into blood
Diffusion:
exchange of CO2 for O2
A respiratory cycle
1 inspiration + 1 expiration
~12-18 cycles/minute in adults
Involves ~500 ml of air with each cycle
Also called a quiet tidal respiration
Quiet tidal respiration
Involves about 500 mL of air
Individuals process around 6,000 to 8,000 mL (6 to 8 liters) of air every minute
Respiration requires
muscular effort
Efficiency of respiration depends on how
individuals control their muscles of
respiration
Respiration is the force behind speech production
Respiration provides energy for oral communication
Typical respiratory development includes
↑ in # alveoli from 25 million at birth to more than 300 million by 8 years of age
↑ in thoracic size (the thorax expands to a greater degree than the lungs)
Results in stretching of the lungs larger than their natural volume secondary to the pleural linkage
respiratory cycles/minute for newboens?
40-70 respiratory cycles/minute at rest for newborns (necessary to meet metabolic needs
respiratory cycles/minute in 5 year olds
25 respiratory cycles/minute in 5 year olds
respiratory cycles/minute in 15 year olds
20 respiratory cycles/minute in 15 year olds
Reserve lung capacity
The stretching of the lungs larger than their natural volume results in a residual volume that explains the reserve lung capacity in adults
Reserve lung capacity results in a reduction in respiratory cycles with development
Capacity
Capacity = combination of volumes relative to physiological limits
Volumes and capacities vary relative to body size, gender, age and height
Tidal volume (TV)
Tidal volume (TV) = volume of 1 respiratory cycle 525 cc
Inspiratory reserve volume (IRV) =
Inspiratory reserve volume (IRV) = volume that can be inhaled after a TV inspiration
2475cc
Expiratory reserve volume (ERV)
Expiratory reserve volume (ERV) = volume that can be exhaled after a TV expiration
1000 cc
Residual volume (RV)
Residual volume (RV) = volume that exists bc of stretching of the lungs larger than their natural volume 1100 cc
Dead air
Dead air = air that is not involved in gas exchange (air that is in lungs but not at alveoli
100 cc
Vital capacity (VC
= capacity available for speech; total inspirable volume after maximal expiration (IRV+ERV+TV; ~4000mL or cc)
Total lung capacity (TLC
vital capacity along with residual volume (TV+IRV+ERV+RV; ~5100cc)
When does vital capacity decrease ?
Vital capacity:
Decreases with age (starting at about 20 years)
Lower for females than males (OH
How are the pressures when the vocal folds are open?
with open vocal folds subglottal = intraoral = alveolar pressure
Pressure measurements
Pressure measurements are relative to atmospheric pressure
Alveolar pressure often measured via esophageal balloon
pressure During inspiration
Thorax expands, and decreases the already negative intrapleural pressure
Increased lung volume results in a negative alveolar pressure
Pressure differential is reversed
Air escaping the lungs to equalize the positive alveolar pressure with the relatively negative atmospheric pressure
Intrapleural pressure is always
Intrapleural pressure is always negative as the lungs are in an expanded state relative to their normal size
This also explains the fact that in normal conditions, the lungs are never entirely deflated
As inspiratory mm begin to work
As inspiratory mm begin to work, the volume between the 2 pleural linings increases and intrapleural pressure becomes even more negative
Surfactant acts
Surfactant acts to reduce surface tension in alveoli resulting in
Reduced alveolar pressure
Maintaining minimal alveolar size
Avoiding passage of capillary fluids into alveoli
what does Lung expansion do to alveolar pressure?
Lung expansion (upon thoracic expansion) results in alveolar expansion and sets up the conditions for ↓ alveolar pressure
Pressure, Flow, Volume Relationships in Inspiration
As diaphragm contracts lung volume ↑ Intrapleural pressure ↓ (Boyle’s Law) Alveolar pressure ↓ (Boyle’s Law) And, finally air flows into the lungs
This process reverses upon expiration
Open vocal folds
provide the conditions for intraoral = subglottic = alveolar pressure
producing voice sounds
To produce voice our vocal folds close
Therefore subglottic pressure ↑, and
Intraoral (supraglottic) pressure approaches atmospheric pressure
Pressure in cm H2O for produce voicing?
When subglottic pressure reaches ~3-5 cm H20 the vocal folds come apart and voicing begins
Pressure in cm H2O for conversation?
Conversational speech requires ~7-10 cm H20
