Week 1 Flashcards
What is the formula for flow?
• formula for resistance?
F = ∆P/R
R = 8nl/r^4
• ∆P = difference in pressure
• R = resistance
What can be said about the rate of oxygen uptake and oxygen consumption and CO2 production and excretion during steady state?
O2 uptake = O2 consumption
CO2 production = CO2 excretion
What is tidal volume (TV)?
• Functional Residual Capacity (FRC)?
• Residual Volume (RV)?
Tidal volume ~500 mL = volume of a normal breathe
Functional Residual Capcacity (FRC) = volume of air leftover in lungs after a normal breath
Residual Volume (RV) = amount of air left in the lungs after maximum exhalation
What volumes compose:
• Inspiratory Capacity?
• Functional Residual Capacity?
Inspiratory Capacity:
• Tidal Volume + Inspiratory Reserve Volume (the extra air you could inhale above and beyond tidal volume)
Functional Residual Capacity:
• Residual Volume + Expiratory Reserve Volume (the air you could exhale if you pushed as hard has you could)
What volumes compose:
• Vital Capacity?
• Total Lung Capacity?
Vital Capacity:
• Tidal Volume + Inspiratory Reserve Volume + Expiratory Reserve Volume
Total Lung Capacity:
•Inspiratory Reserve Volume + Tidal Volume + Expiratory reserve volume + Residual Volume
T or F: Residual Volume can’t be measured with a spirometer
True
What is the normal FEV1/FVC ratio?
80% which means you exhale most of your breathe in the 1st second
Someone has a FEV1/FVC ratio that is less than 0.7, name 4 diseases they might have?
COPD:
1) Emphysema
2) Chronic Bronchitis
3) Bronchietasis
4) Asthma
Someone has an FEV1/FVC that is greater than 0.8, what are some possible pathologies that could cause this?
Mechanical Breathing Disorders:
• Weakness, Neuromuscular
Interstitial Diseases: • Pulmonary Fibrosis • ARDS • Sarcoidosis • Hypersensitivity Pneumonitis
How can the physiological dead space be measured?
End tidal Pco2 / arterial Pco2
• Less CO2
How would a pulmonary embolus affect alveolar dead space?
It would increase because no blood is supplying that lung tissue
What is the formula for Minute Ventilation?
• Alveolar ventilation?
MINUTE VENTILATION:
Vmv = TV x f
- TV = tidal volume
- f = respiratory rate
ALVEOLAR VENTILATION:
Valv = (TV - dead space)*Respiratory Rate
T or F: if you want to take up a greater amount of O2 increasing breathing rate is the most important factor.
False, Depth of breathing is a more important factor in increasing Alveolar Ventilation
What is the transmural pressure between breaths if the elastic recoil of the lungs is X.
X - the transmural exactly opposes the elastic recoil of the lungs, this keeps the lungs from collapsing
How many cm H2O is equivalent to 760 mmHg?
1033 cmH2O = 760 mmHg
What is the primary driving force of airflow into and out of the lung?
• Pressure Difference between the mouth and Alveoli
What is the formula to calculate Transplural pressure?
Ptp = Palv - Pip
Intrapleural Pressure = Pressure outside the lungs
Alveolar Pressure = Pressure Inside the lungs
What is Ptp (transpleural pressure) between breaths?
Ptp = 0
Name the nerve and muscles responsible for inspiration?
Scalene
Sternocleidomastoids
EXTERNAL INTERCOSTAL MM.
Name the muscles responsible for expiration?
NONE - at rest
During Ex.:
• INTERNAL INTERCOSTALS
• External Obliques
• Transverse abdominus
When is the maximal magnitude of Alveolar pressure achieved in inspiration?
•When is elastic recoil of the lung maxed out?
Palv = most negative 1/2 through inspiration
Elastic Recoil = Maximal at the end of inspiration
What is the difference in response of a compliant lung compared to a non-compliant lung with the same Transpleural pressure?
Compliant Lung will inflate more with the same applied pressure
What is hysteresis?
• explain why we see it?
Hysteresis:
• Asymmetry of pressure-volume curves for inspiration and expiration
• Caused by surface tension that is higher in the closed lung which reduces its compliance
Explain what happens to the following in restrictive disease. • FVC • TLC • RV • FRC
They have difficulty getting air in so all these values are decreased.
Explain what happens to the following in obstructive disease. • FVC • TLC • RV • FRC
FRC- increased (more air is just hanging out in the lungs)
TLC - Increase (barrel chested)
RV - Increased (b/c its just more empty space)
FVC - Decreased b/c FEC is decreased
Why do people with emphysema purse their lips?
- To prevent airway collapse of LARGER AIRWAYS during FORCED expiration
- AIRWAY COLLAPSE happens because there is not enough pressure generated in the airway to push out on the walls and prevent collapse
Differentiate the 4 types of COPD based on their effect on flow.
FLOW = Q = Patm - Palv / R
∆P - decreased in emphysema
R - increased in asthma and bronchitis
What two factors determine lung compliance?
- Tissue Properties: connective tissue and interdependence by shared walls of the alveoli
- Surface Properties: surface tension determines this
What happens to alveoli that are not coated by surfactant?
Atelectasis
What is the formula for collapsing pressure?
P = 2T/r
- T = surface tension
- r = radius of the sphere
What airway has the highest resistance to fluid flow?
Medium Bronchi
What is the normal respiratory quotient (RQ)?
• what is this determined by?
normal RQ = 0.8
Determined by what we eat.
• RQ carbs = 1
• RQ fat = 0.7
• RQ protein = 0.8
What is the normal partial pressure of oxygen in air?
• how do we come up with this number?
159 mmHg = 760 mmHg x 0.21
or for inhaled air:
150 mmHg = (760 mmHg - 47 mmHg) x 0.21
T or F: at the same partial pressure there is the same amount of dissolved CO2 in water as there is O2.
False, solubility depends on a constant - remember Henry’s law Cx = alphaPx
What is Fick’s law?
gas flow (vol/time) = (A/z) x D x (P1 - P2)
- A = Area available for diffusion
- z = thickness of barrier
- D = diffusion constant
- P = partial pressure
What is the diffusion quotient in Fick’s law dependent on?
- Solubility of the Gas
* Size of the gas
Which diffuses faster into blood or tissue CO2 or O2?
CO2, it dissolves about 20x faster
What is the partial pressure of O2 and CO2 in: • Air • Alveoli •Pulmonary Veins/Systemic Arteries • Pulmonary Arteries/ Systemic Veins
Air:
• PO2 = 160 mmHg
• PCO2 = 0.3 mmHg
Alveoli:
• PO2 = 105 mmHg
• PCO2 = 40 mmHg
Pulmonary Veins/ Systemic Arteries:
• PO2 = 100 mmHg
• PCO2 = 40 mmHg
Pulmonary Arteries / Systemic Veins:
• PO2 = 40 mmHg
• PCO2 = 46 mmHg
What determines the alveolar partial pressure of CO2 (PACO2)?
• The amount produced in the body and alveolar ventilation
PACO2 ~ Vco2 (rate of CO2 production) / Valv (rate of alveolar ventilation)
What happens to PACO2 as alveolar ventilation increases?
PACO2 is reduced by increased alveolar ventilation because you get more CO2 out and more oxygen in
What is the driving stimulus for respiration?
PCO2
Define Hyperventilation and Hypoventilation?
Hypoventilation:
• alveolar ventilation is to low for CO2 production
Hyperventilation
• Alveolar ventilation is excessive for CO2 production
What 3 factors determine the alveolar partial pressure of oxygen (PAO2)?
•What is the formula?
PO2 of inspired air
Alveolar Ventilation - more ventilation = greater PO2
Cellular O2 consumption - increased then PAO2 will decrease because more gets sucked into the blood
Formula:
• PAO2 = PIO2 - PACO2/R
- PIO2 = inspired O2
- PACO2 = alveolar CO2
- R = CO2 production/O2 consumption (typically 0.8)