Lectures 1 & 2 Flashcards
What is the Physiological definition of Respiration?
The transport of Oxygen from ambient air to cells in the tissues and the transport of CO2 out of the tissues into ambient air
Why do we need a respiratory system?
Anything bigger than a cubic millimeter needs blood supply due to limited diffusion because of size
What are the 4 Phases of Respiration?
- Ventilation
- Diffusion (Alveoli to Pulmonary Capillaries)
- Transport
- Diffusion (O2 to Tissue and CO2 to blood)
What jobs do the lung do?
- Conduction of air
- Diffusion of gas
- Transport
- Metabolism (in Epithelial cells)
- Defense
What is the Conducting Zone and what parts of the lung are included here?
The Anatomical Dead SpaceParts AKA parts of the lung that conduct inspired air but DO NOT take part in gas exchange (diffusion):
- Trachea (0)
- Bronchi (1-3)
- Bronchioles (4-5)
- Terminal Bronchioles (6-16)
Why is branching of the lungs important?
Branching of the Lungs INCREASES the Cross-Sectional Area of the Airways which DECREASES Pressure Change which DECREASES Flow and FACILITATES Gas Exchange
What is the equation for Change in Pressure (∆P)?
∆P= Force/Area
How does ∆P effect Flow (equation and relationship)?
Flow= Volume/Time
AND
Flow= ∆P/Resistance
So decreased Pressure Change also decreases flow
Where is Flow the fastest?
Trachea and Bronchi (Upper parts of the Conducting Zone) since they have the smallest area
What is the relationship between Cross-Sectional Area and Velocity?
Inversely Proportional
As Cross-Sectional Area goes up, Velocity goes down
What is the definition for the diffusion of gas?
Passive movement of molecules/particles DOWN their concentration gradient
What factors would increase the Rate of Diffusion for a gas across a permeable membrane?
- (A) Increase in Surface Area of the Membrane
- (T) Decrease in Thickness of Membrane
- (∆P) Increase in Partial Pressure gradient across the membrane
- (D) Increase the Diffusion Coefficient of the Gas
What is the formula for the Diffusion Coefficient?
D= Solubility Coefficient/ Square Root(Molecular Weight of the gas)
What is the one exception to the Diffusion Coefficient being greatest for small molecules?
Helium, it is the smallest gas molecule but it diffuses very slowly.
CO2 vs. O2 Diffusion
CO2 is very soluble and diffuses 20x faster than O2
What are the constituents of the Alveolus?
- Type I Pneumocytes (majority of lung Surface Area)
- Type II Pneumocytes (make surfactant)
- Very thin Alveolo-Capillary Membrane (0.3-0.5 micrometers)
What is usually not impacted by a thickened Alveolo-Capillary Membrane, unless you are in a state of very serious disease?
CO2 diffusion because it is so soluble
What are some facts about Pulmonary Circulation?
- Lung is reservoir for blood
- Lung receives almost all CO
- Low Resistance Circuit
- Good Flow (Even though Resistance is low, so is ∆P)
- Alveoli are bathed in blood for efficient gas exchange
Describe Vascular Resistance in Extra-Alveolar Vessels
J-Shaped curve where Vascular Resistance drops then increases greatly when Volume is increased
What is Pulmonary Vascular Resistance?
A U-shaped curve that is the Sum of Resistance in Alveolar Blood Vessels and Resistance in Extra-Alveolar Blood Vessels
What is Functional Residual Capacity?
Resting state or the “Sweet spot” where blood resistance is the lowest
What happens to vessels in the lung during LOW lung volumes?
- INCREASED Extra Alveolar Vessel Resistance
2. DECREASED Alveolar (Capillary) Vessel Resistance
What happens to vessels in the lung during HIGH lung volumes?
- DECREASED Extra Alveolar Vessel Resistance (due to expanding lung pulling vessels apart)
- INCREASED Alveolar (Capillary) Vessel Resistance
What is Recruitment?
- Occurs during exercise
2. Blood vessels that are usually occluded in the resting state become active which increases blood flow