Respiratory Physics and Medical Gases Practice Flashcards

Comprehensive vocabulary flashcards covering gas laws, fluid mechanics, humidity, and respiratory physiology based on the lecture notes.

Air Composition

Consists of $20.95\%\,O_2$, $78.1\%\,N_2$, and $\sim 1\%$ trace gases (e.g., Ar).

Atelectasis

The medical term for alveolar collapse, which surfactant helps to prevent.

BTPS

Stands for Body Temperature, ambient Pressure, Saturated; defined by conditions of $37^\circ\text{C}$, a water vapor pressure of $47\,\text{mmHg}$, and water content of $44\,\text{mg/L}$.

Water Vapor Pressure at Body Temperature

$47\,\text{mmHg}$.

Water Content at Body Temperature

$44\,\text{mg/L}$.

Laplace's Law

States that pressure inside an alveolus is directly proportional to surface tension and inversely proportional to the radius of the alveolus.

Surfactant

A substance secreted by Type II alveolar cells that reduces surface tension and lowers alveolar pressure to keep alveoli open.

Viscosity

The resistance of a fluid to flow, or the friction within a liquid; higher viscosity results in greater resistance.

Laminar Flow

Fluid movement in smooth, straight, parallel layers where velocity is highest in the center and slowest near the walls of the tube.

Surface Tension

The attraction of liquid molecules to one another at the liquid-gas interface, causing the surface to act like a stretched film.

Archimedes' Principle

States that the buoyant force on an object equals the weight of the fluid displaced by that object.

Hydrometer

An instrument based on Archimedes' Principle used to measure the density (gravity) of a liquid.

Pascal's Principle

States that any pressure applied to an enclosed fluid is transmitted equally throughout the fluid and to the container walls.

Absolute Humidity

The actual or current measure of moisture content in a gas mixture, expressed in $\text{mg/L}$.

Relative Humidity

The ratio or percentage of the actual amount of water vapor present to the maximum amount the air could hold (capacity) at that temperature.

Saturated Gas

A gas containing the maximum amount of water it can possibly hold ($100\%$ humidity).

Humidity Deficit

The difference between the saturated capacity at $37^\circ\text{C}$ and the absolute humidity.

Liquid Oxygen ($LOX$) Boiling Point

$-183^\circ\text{C}$.

Liquid Oxygen Expansion Ratio

When liquid oxygen changes to gas, it expands approximately $860$ times ($1\,\text{L}$ of liquid produces about $860\,\text{L}$ of gas).

Heliox ($80:20$) Flow Factor

$1.8\times$; used to calculate actual flow by multiplying the flowmeter reading by $1.8$.

Nitric Oxide ($NO$)

A medical gas used to treat term and near-term infants, specifically for pulmonary hypertension.

Oxygen Density

$1.429\,\text{g/L}$.

Dynamic Equilibrium

Reached when the rate of evaporation equals the rate of condensation, resulting in saturated air.

Vaporization

The phase change from a liquid to a gas (also known as evaporation).

Oxygen Cylinder Ratio

The volume of gas is directly proportional to its pressure; high pressure indicates more oxygen in the tank.