Ventilation Flashcards
What activates ILC1 to push a Th1 response? What activates ILC2 to push a TH2 response?
1 - prescence of IL-12
2 - alarmins
both need IL-2, an mitogen/ T cell activator secreted by Th
What are the 3 ILC2 alarmins?
IL-25, IL-33, TSLP (thymic stromal lymphopoitin)
together these push a barrier tissue towards secretion of TH2 type cytokines
What is Boyle’s Law? HOw does it apply to ventilation?
Pressure and volume are inversely related.
Inhalation: The chest cavity volume increases, pressure decreases, and air flows in.
Exhalation: The chest cavity volume decreases, pressure increases, and air is pushed out.
What is Laplace’s Law?
Laplace’s Law explains the relationship between pressure (P), surface tension (T), and radius (r) in a sphere, such as an alveolus:
Pressure and Surface Tension:
The inward pressure inside a sphere (like an alveolus) increases as surface tension increases.
Pressure and Radius:
Smaller alveoli (smaller radius) experience higher inward pressure, making them more likely to collapse.
What is daltons Law?
each type of gas has its own pressure indepedent of other gases present in a mixture.
the pressure of an individual gas is called its partial pressure.
Takeaway:
At high altitudes and in the alveoli, the lower partial pressure of oxygen explains why less oxygen is available for breathing and gas exchange.
What is Fick’s law? what diffusions faster CO2 or O2?
More surface area = more gas diffusion
Surface Area (A):
More surface area = More gas diffusion.
Partial Pressure Difference (P1 - P2):
Larger difference in partial pressures = Faster diffusion.
Membrane Thickness (T):
Thicker membrane = Slower diffusion.
Diffusion Constant (D):
Depends on gas solubility and molecular weight.
CO₂ diffuses faster than O₂ because it is more soluble in blood.
- Efficient Gas Exchange: Requires large surface area (alveoli), thin membranes (respiratory membrane), and significant pressure differences.
- Clinical Relevance: Diseases like emphysema (reduced area) or fibrosis (increased thickness) impair gas exchange.
- CO₂ Diffusion: Faster due to higher solubility, even with a smaller pressure gradient.
What is functional residual capacity (FRC)? What’s its functional role and disease implications?
Functional Role: FRC represents the lung volume at the end of a normal exhalation.
It ensures continuous gas exchange between breaths, preventing alveolar collapse.
Disease Implications:
- In restrictive diseases (e.g., pulmonary fibrosis), FRC is reduced because of stiff, non-compliant lungs.
- In obstructive diseases (e.g., COPD, asthma), FRC increases due to air trapping and hyperinflation.
What is minute respiratory volume (MRV)?
The total amount of new air that moves into the respiratory system each minute.
Tidal Volume (TV): The air you move in and out of your lungs during quiet breathing, about 500 mL.
Respiratory Rate: The number of breaths per minute, usually 12 breaths/min in adults.
Normal MRV:
At rest: 500 mL × 12 bpm = 6 L/min
What type of pressure is essential to keep the lungs inflated?
Negative pleural pressure.
* In a pneumothorax, this negative pressure is lost, causing lung collapse.
The mediastinal membrane protects the other lung from collapsing in such cases
what is the definition of pleural pressure and what happens to the pressure during inspiration and expiration?
Definition: The pressure in the pleural space, which is always negative under normal conditions.
Inspiration: The pleural pressure becomes more negative as the diaphragm contracts, increasing the thoracic cavity volume and pulling the lungs outward. This negative pressure helps expand the lungs.
Expiration: The pleural pressure becomes less negative as the diaphragm relaxes, and the lungs recoil inward.
Summary of airflow resistance and breathing, compare inspiration and expiration
Inspiration:
- Pleural pressure becomes more negative.
- Alveolar pressure drops below atmospheric pressure, pulling air in.
- Airflow peaks and tidal volume rises.
Expiration:
- Pleural pressure becomes less negative.
- Alveolar pressure becomes positive, pushing air out.
- Airflow reverses, and tidal volume decreases.
- This sequence ensures efficient ventilation, maintaining proper gas exchange in the lungs.
what is surfactant and what’s its role in the lungs?
Surfactant, a substance produced by type 2 alveolar cells (pneumocyte), reduces surface tension, stabilizing alveoli of different sizes and preventing collapse (atelectasis).
(key to Laplace’s law)
Identify Which airway has the greatest resistance? What is the clinical relevance of resistance in obstructive lung diseases?
Airway resistance is highest in the larger airways, such as the segmental bronchi
Conditions like asthma or COPD can increase resistance in small airways due to inflammation, mucus, or structural collapse, changing the normal distribution of resistance and increasing total resistance.
what is Bernoulli principle? Relate to COPD patients
- Faster airflow (velocity) creates lower pressure inside the airway walls (Bernoulli Principle), helping keep the airways open during exhalation.
COPD patients breathe at higher lung volumes to reduce airway resistance and maintain open airways, leveraging both mechanical tethering and airflow dynamics
is there increased velocity on expiration or inspiration? Think about air flow direction?
Airflow Direction: Always flows from areas of higher pressure to lower pressure.
Increase in velocity on expiration
when does intrapleural pressure become positive?
only on forced expiration
In conditions like COPD, airway collapse may occur during forced expiration because small airways cannot maintain sufficient pressure to remain open.
In healthy lungs, collapse occurs in the bronchi (with cartilage), in emphysema where does collaspe occur?
in bronchioles (no cartilage)
- In emphysema, loss of elastic tissue makes small airways prone to collapse during expiration, increasing resistance.
- Bernoulli effect and increased intrapleural pressure exacerbate airway narrowing and collapse.
This leads to air trapping, hyperinflation, and greater breathing difficulty.
at high altitudes the partial pressure of oxygen drops along with atmospheric pressure.
At high altitudes and in the alveoli, the lower partial pressure of oxygen explains why less oxygen is available for breathing and gas exchange.
describe gas movement from alveoli into blood and vice versa.
Oxygen (O₂): Moves from alveoli (high pressure) into the blood (low pressure) due to the pressure gradient.
Carbon Dioxide (CO₂): Moves from blood (high pressure) into the alveoli (low pressure) for exhalation.
What impacts the diffusion capacity of the lung? When is it reduced?
The lung’s ability to transfer gases depends on surface area, membrane thickness, and the pressure gradient, with diseases affecting any of these factors reducing diffusing capacity.
- Emphysema (loss of surface area).
- Fibrosis (thicker membranes).
Anemia (reduced hemoglobin for binding).
what is the steep vs plateau regions on the Hb dissociation curve represent?
The curve is sigmoidal with a steep slope at low partial pressures of oxygen and a more gradual slope at higher partial pressures.
What is P50 value? What does a higher or lower P50 mean?
The partial pressure of oxygen (P at which hemoglobin is 50% saturated.
Indicates hemoglobin’s oxygen affinity:
Lower P50: Higher affinity (curve shifts left).
- decreased temp, CO2 or 2,3 DPG, CO poisoning
Higher P50: Lower affinity (curve shifts right)
- increased temp, CO2, or 2,3 DPG
When is 2,3 DPG increased
Increases during hypoxic conditions (e.g., high altitude), facilitating oxygen unloading at tissues by shifting the curve right.
Right Shift (lower affinity): Helps oxygen unloading at tissues.
Left Shift (higher affinity): Helps oxygen loading in the lungs.
In a healthy lung where does collapse occur? vs emphysema?
In healthy lungs, collapse occurs in the bronchi (with cartilage).
In emphysema, collapse occurs earlier (in bronchioles), worsening airflow obstruction.
In emphysema, loss of elastic tissue makes small airways prone to collapse during expiration, increasing resistance
T/F: is bronchial circulation the same as pulmonary?
NO
What is the function of the bronchial circulation
NOURISH walls of conducting airways and tissues by distrubuting blood
What are the functions of the pulmonary circulation
- gas exchange
- filter (thromi)
- metabolic organ (angiotension 2 and breaks down histamine, serotonin, bradykinin)
- blood reservior (10% of total blood (500ml) mobilized during shock
what part of the lung circulation can do angiogenesis and why can it
bronchial
if there is an obstruction it can form new vessels for collateral circulation to the lung parenchyma
- important in pulmonary embolism
unlike the systemic circulation, the pulmonary system is ___ flow, ____ pressure, ____ resistance?
high flow
low pressure
low resistance
normally dilated, systemic is normally constricted
what are the systolic and diastolic pressures of the pulmonary system
25/8
if there is more blood coming from the heart (increase cardiac output) what happens to the resistance in the pulmonary system
higher cardiac output = lower pulmonary pressure to ensure pulmonary hypertension doesnt happen
when does pulmoanry vascular resistance increase?
at either high or low lung volumes
lowest at FRC
what does smoking do
decreases the pulmonary capillary cross sectional area
contributes to the increased pilmonary artery pressure
