Pulmonary 1 Flashcards
Inspiratory Reserve Volume (IRV)
The additional volume person is CAPABLE of inhaling after normal, quiet inhalation
Tidal Volume (TV)
Volume of air inhaled and exhaled during normal breathing ~500mL
Residual Volume (RV)
Volume remaining in lungs after maximal exhalation
Expiratory Reserve Volume (ERV)
The additional volume person is CAPABLE of exhaling after normal, quiet exhalation
Total Lung Capacity (TLC)
Volume of gas in lungs after maximal inhalation
~7L
TLC = TV + RV + ERV + IRV
Vital Capacity (VC)
Max volume of air that can be exhaled AFTER maximal inhalation
VC = TV + IRV + ERV
Functional Vital Capacity (FVC)
Vital Capacity measured at maximum force
Inspiratory Capacity (IC)
Maximum volume that can be inspired after expiration after normal quiet breathing
IC = TV + IRV
Functional Residual Capacity (FRC)
Volume remaining in lungs after normal TV exhaled
FRC = ERV + RV
With Helium:
(C1)(VS) = (C2)(VS + FRC)
FRC = (VS) x (C1/C2-1)
Define the Conducting and Gas exchange Airways
Conducting Mouth to Terminal Bronchioles ONLY air movement No Gas Exchange Branch up to 23 times Radius decreases with each branch Anatomical Dead Space ~150 mL
Gas Exchange Airway
Respiratory bronchioles to Alveoli
GAS EXCHANGE/Surfactant production
Type I and Type II alveolar cells
Epithelial cells
Type I = GAS EXCHANGE
Very Thin
Type II = SURFACTANT
NO Gas Exchange
Two important concepts about the lungs from top to bottom
- Gravity- Blood pressure will be lower at the top and Higer at the bottom
- Stretch- Amount of stretch from top to bottom depends on the mass below that point (SLINKY)
Resistance and area, formula and relationship
R ~ 1/A
Area = (Pie)r2
R ~ 1/(Pie)r2 or R ~ 1/r2
Resistance in the conducting zone will increase with each branch until we get to the Respiratory zone where surface area greatly increases and resistance is almost nothing.
Two Important cells in conducting airways
Goblet cells- produce mucus
Prevents large things like
sand from getting to alveoli
Everywhere above alveoli
Including respiratory bronchioles
Ciliated cells move mucous up and out
Located where goblet cells are
Alveolar macrophages
Dust cells- Phagocytose Pathogens
Clara Cells and Goblet cells relationship
Clara cell are secretary cells in terminal bronchioles, they increase in number the further down we are in the bronchioles, while, goblet cells decrease/are absent in terminal bronchioles
Kulchitke cells
Neuroendocrine cells secrete paracrine factors and part of diffuse neuroendocrine system.
Relationship of pressure flow and resistance in lungs.
Pulmonary circulation is low pressure, low resistance and high flow, think Ohms law (Flow equals change in pressure over resistance)
Best vascularized area in body, 100% ob blood from RA goes through the lungs which is the same as the mat of blood gsong through the rest of the body. It MUST BE LOW RESISTANCE
If we decrease resistance, we increase flow. Ohms law
Important features of Respiratory Zone.
- Respiratory bronchioles and alveolar ducts
- Cross sectional area increases, but MOST IMPORTANTLY - Surface area increases allowing for gas exchange
- Velocity of flow decreases-gas stops and comes back out
- Ficks
Ficks Principal
Ficks = (Area)(Diffusion)(C1-C2)
———————————-
T
C = concentration or it can be pressure P1-P2
T= Thickness of membrane
Thinner the wall, easier the gas exchange
Larger the area the greater the gas exchange
Diffusion = how well a particular molecule diffuses
Fused Basal Lamina
Basement membrane of capillary lumen and Type I cells of alveoli fuse together to form fused basal lamina. Used for gas exchange.
Whole Body Plethymograpy
Based on Boyle’s law
P1)(V1) = (P2)(V2
Used for measuring FRC
What can Spirometry measure an not measure
It can measure all the components of Vital Capacity (TV, ERV, IRV)
It CANNOT measure residual volume so we measure functional residual capacity with helium
What are the primary functions of FRC?
- O2 reserve/bank when needed
- Keeps intrapleural pressure negative
- IS maximizes FRC
- Point when elastic recoil and chest wall are balanced
Ventilation of exhaled air
MINUTE VENTILATION
Ve = R x VT
Ve is always larger than Va because some air is in the conducting airways
Ve~7.5 L/min (500 L/breath, 15 breaths/min)
Alveolar ventilation
Ventilation of respiratory zones of the lungs
Va = R (VT - VD)
Va = Ve - VD
Va ~
VD~ 150 ml/breath, at 15 breaths per minute VD is approximately 2.25 L/min
Determining Dead Space
Volume of Gas that does not eliminate Co2
VD = PaCo2 - PECo2
—– ———————-
VT PaCo2
Simplified:
VD = VT x PaCo2 - PECo2
———————-
PaCo2
PaCo2 = Arterial Co2
PECo2 = Exhaled Co2
Assume arterial Co2 = Alveolar Co2
Partial pressures of room air compared to that of inspired gas
Room Air = 21% O2 and 79% N2
Ptot = (0.21 x 760) + (0.79 x 760)
Inspired gas = is humidified
H2O takes up ~ 47mm Hg
Ptot still must equal 760
PItot = 47mmhg
+ (0.21 x (760-47))
+ (0.79 x (760- 47))
If someone has a fever the partial pressure of H2O will increase leaving less room for O2
What is unique about the
Pressure of alveolar O2
Must consider the exchange of O2 and Co2.
Assume PaCo2 = PACo2
arterial = Alveolar
Must consider metabolism as well
Respiratory exchange quotient = 0.8 on a mixed diet
PAO2 = PIO2 - (PaCo2 / R)
= 150 - 50
= 100
So from a blood gas we can figure out PAO2
This will also change at different altitudes
Alveolar gas equation at SEA LEVEL
Define each equation
PAO2 = FiO2 x (760-47) - pACo2/R
~100mmHg
PAO2 = partial pressure of alveolar oxygen
FiO2 = Fractional concentration of inspired O2
760 = total brometric pressure of the atmosphere at sea level in mmHg
47 Partial pressure of water vapor in alveolus pACo2 = Partial pressure of Co2 coming from blood in mmHg
R = Respiratory exchange quotient
What is the Respiratory exchange quotient?
The amount of Co2 generated per O2 molecule utilized
At basal metabolic rate it is 0.8
What is the pressure of Arterial 02
In a healthy inividual at sea level ~95 mmHg
What is a normal Alveolo-arterial gradient
When will it change
Alveolar pressure at sea level is ~100, so the Alveoli-arterial gradient ranges from 5-10 mmHg
It is INCREASED when there is a diffusion problem, Alveolus to artery
Problem in ANY non-ventilated or poor diffusion space
DLco and related formulas
What will make DLco cage and why?
DLco = (A/T) x Dco
DLco = Vco /PAco
we get values using Ficks law
Vgas = A x Diffusion constant X (P1-P2)
———————————————–
Thickness
Deco give us lung diffusion for for CO and tells us how well gasses (O2) will diffuse across a membrane
DLco DECREAESES as someone gets sick- as someone gets thicker O2 will struggle more to cross the membrane than CO2, this is because CO2 is soluble in blood
This is why we give O2 - OXYGEN will help if diffusion is really poor
Explain the lung Zones
Zone I = alveoli most stretched and capillaries most compressed (Low ventilation because alveoli already stretched, least profusion)
Zone II =Alveoli mediumly stretched and capillaries medium size
Zone III = Alveoli least stretch and blood vessels largest. (Most Profusion, most ventilation because the smaller UNSTRETCHED alveoli will get the most flow)
