Chapter 14: Spirometry and Respiratory Function Flashcards
(27 cards)
Tidal Volume (TV)
500 mL
Amount of air exchanged in a ‘quiet inspiration’
Inspiratory Reserve Volume (IRV)
3000 ml
Amount of air inspired after a quiet inspiration
Expiratory Reserve Volume (ERV)
1100 ml
Amount of air expired after a quiet expiration
Residual Volume (RV)
1200 ml
Air remaining in lungs after maximum expiration
Vital Capacity (VC)
4800 mL
TV + IRV + ERV
Inspiratory Capacity (IC)
3600 mL
TV + IRV
Functional Residual Capacity (FRC)
2400 mL
ERV + RV
Total Lung Capacity (TLC)
6000 mL
All volumes
Forced Expiratory Volume
COPD, Such as Asthma show reduced FEV, it is more difficult to air to flow
Boyle’s Law
↑Pgas=↓Vgas or ↓Pgas=↑Vgas
Lungs can change Volume of gas; therefore can change Pressure of gas.
Charles’s Law
↓Vgas =↓Togas or ↑Vgas=↑Togas
Lungs raise Temperature of gas which increases Volume of gas.
Dalton’s Law
Gas pressure (atmosphere) is the summation of the partial pressures of the different gases in it, such as PO2 + PCO2 + N2, etc.
Physical Laws
Air moves from high pressure P1 to low pressure P2
Diaphragm Contracting
Atmospheric Pressure at Sea Level: 760 mmHg
Intrapulmonary (Alveolar) Pressure: 757 mmHg
Intrapleural Pressure: 754 mmHg (-6 mmHg)
Diaphragm Relaxing
Atmospheric Pressure at Sea Level: 760 mmHg
Intrapulmonary (Alveolar) Pressure: 763 mmHg
Intrapleural Pressure: 756 mmHg (-4 mmHg)
Resistance and Airflow
F=ΔP/R, where F=flow, P=pressure, R=resistance
Air flow (F) is decreased by increased resistance (R): Decreased bronchi radius is called broncheoconstriction (allergies, cold air, anaphylactic shock, inflammation, or mucous accumulation)
increased bronchi radius is called broncheodilation (Sympathetic nerves: epinephrine, norepinephrine)
Factors that Influence Respiratory Rate
Regulated by a central pattern generator in medulla
Normal ‘quiet’ breathing (when at rest but awake) is 500 ml X 12 breaths per minute = 6000 ml of air per minute
Hyperventilation
means increased respiratory rate – caused by: Sympathetic stimulation (epinephrine-bronchiodilation), blood acidosis, hypercapnia (high CO2 in blood plasma), low [O2] in blood, emotional distress, pain.
results in ↑CO2 expelled from body -> ↓Blood [CO2] (hypocapnia) -> ↓Blood [H+] (which is alkalosis),
Local Correction/Compensation: ↑vasoconstriction brain blood vessels which ↓Blood Flow to brain ↓brain perfusion dizziness fainting.
Systemic Correction: Breathing into a paper bag
Hypoventilation
means decreased respiratory rate – caused by:
Inhibition of reticular formation (sleep), obstruction, holding breath, hypocapenia (low CO2 in blood plasma), emotional distress, pain.
results in ↓CO2 expelled from body -> ↑Blood [CO2] (hypercapnia) -> ↑ Blood [H+] (blood acidosis), also results in ↓[O2] blood -> ↓tissue perfusion -> ↓aerobic cellular respiration -> ↓ATP
‘Local’ compensation/correction: blood vessels respond by ↑vasodilation (due to epinephrine) to ↑tissue perfusion,
Systemic Correction/compensation: brainstem ‘forces’ ↑sympathetic activity
Cellular respiration
during aerobic respiration, mitochondria use glucose (6-carbon sugar) in cyclical reactions to produce ATP and give off CO2 as waste, O2 is used as the final electron acceptor
Carbonic anhydrase (CAH) catalyzes: CO2 + H2O H2CO3 HCO3- + H+
Increased [CO2] and [H+] are detected in blood and cerebrospinal fluid by
chemoreceptors
Inspiratory neurons
(medulla) fires during normal, ‘quite’, inspiration, innervates diaphragm
Expiratory neurons
fire ONLY during forced expiration. innervates intercostal and abdominal muscles.
Law of Laplace
pressure on alveolar wall is proportional to its surface tension, and inversely proportional to its radius.
alveolus will tend to collapse with ↑surface tension (elasticity/fluid) or ↓radius, because alveolar walls are elastic and hydrogen bonding between water molecules on the outer wall of the alveoli pushes it inward during expiration (small radius)
