Alveolar Air Systems lecture 2

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Questions and Answers

Which equation is used to measure dry gas?

$PGas = PB times F (correct)

$PGas = (PB + PH2O) times F$

$PGas = PB * PH2O times F$

$PGas = (PB - PH2O) times F$

What does PGas represent in the equation?

Partial pressure of gas (correct)

Barometric pressure

Water vapor pressure

Fractional concentration of gas

What is the sum of the partial pressures of a gas according to Dalton's law of partial pressure?

Equal to the total pressure (correct)

Less than the total pressure

Greater than the total pressure

Unrelated to the total pressure

Which gas is responsible for the majority of atmospheric pressure?

Nitrogen Signup and view all the answers

What happens to barometric pressure as altitude increases?

It decreases Signup and view all the answers

Where does the saturation of inhaled air take place?

In the nasal cavity Signup and view all the answers

At what temperature does inhaled air become 100% saturated in the airway?

37°C Signup and view all the answers

What is the partial pressure of Nitrogen gas inhaled in the trachea if the functional composition of nitrogen gas is 0.79?

563 mmHg Signup and view all the answers

Is the saturation with H2O pressure dependent?

No Signup and view all the answers

Which cells in the alveoli are responsible for secreting surfactant?

Alveolar type II cells Signup and view all the answers

What is the function of surfactant in the alveoli?

To decrease surface tension in the alveolus Signup and view all the answers

What drives oxygen from the alveoli into the tissue?

Low concentration of oxygen in the capillaries Signup and view all the answers

Where does carbon dioxide diffuse from and into in the respiratory system?

From the blood to the alveoli Signup and view all the answers

What is the partial pressure of carbon dioxide in the alveoli?

40mmHg Signup and view all the answers

Why does carbon dioxide diffuse from the blood into the alveoli?

Due to high concentration of CO2 in the blood Signup and view all the answers

What are the characteristics of alveolar type I cells?

Large and thin cells with a large total surface area Signup and view all the answers

Which equation is used to calculate the partial pressure of oxygen in the alveolus?

PAO2 = PB - PH2O x FIO2 - PACO2/R Signup and view all the answers

What is the value of the respiratory quotient (R) used in the alveolar gas equation?

0.8 Signup and view all the answers

What does PIO2 represent in the alveolar gas equation?

Inspired partial pressure of oxygen Signup and view all the answers

What is the formula for calculating PIO2 in the alveolar gas equation?

PIO2 = PB - PH2O x FIO2 Signup and view all the answers

What does PACO2 represent in the alveolar gas equation?

Partial pressure of carbon dioxide in the alveolus Signup and view all the answers

Which of the following will cause PACO2 to increase?

Increased metabolic CO2 production Signup and view all the answers

What happens to PACO2 during hypoventilation?

PACO2 increases Signup and view all the answers

What is the partial pressure of carbon dioxide in the alveolus during hyperventilation?

PACO2 < 40 mm Hg Signup and view all the answers

Which equation is used to calculate respiratory gas exchange (R)?

R = V CO2 / VO2 Signup and view all the answers

What is the usual value of respiratory gas exchange (R)?

0.8 Signup and view all the answers

What is the equation for calculating respiratory gas exchange (R) in terms of CO2 and O2?

R = V CO2 / V O2 Signup and view all the answers

Study Notes

Measuring Gas Pressure

The equation used to measure dry gas is not specified in the provided text.
PGas represents the partial pressure of a gas in the equation.

Dalton's Law of Partial Pressure

The sum of the partial pressures of a gas is equal to the total pressure of the gas mixture, according to Dalton's law of partial pressure.

Atmospheric Pressure

Nitrogen gas is responsible for the majority of atmospheric pressure.

Barometric Pressure

Barometric pressure decreases as altitude increases.

Saturation of Inhaled Air

The saturation of inhaled air takes place in the nose and mouth.
Inhaled air becomes 100% saturated in the airway at a temperature of 37°C (normal body temperature).

Partial Pressure of Nitrogen Gas

The partial pressure of Nitrogen gas inhaled in the trachea is 0.79 × PBar (barometric pressure).

Saturation with H2O Pressure

Saturation with H2O pressure is dependent on the partial pressure of water vapor.

Surfactant in Alveoli

Type II cells in the alveoli are responsible for secreting surfactant.
The function of surfactant in the alveoli is to reduce the surface tension of water, allowing the alveoli to expand and contract more easily during breathing.

Oxygen Diffusion

Oxygen is driven from the alveoli into the tissue due to the partial pressure gradient.

Carbon Dioxide Diffusion

Carbon dioxide diffuses from the blood into the alveoli and out of the alveoli into the atmosphere.
The partial pressure of carbon dioxide in the alveoli is approximately 40 mmHg.
Carbon dioxide diffuses from the blood into the alveoli because of its higher partial pressure in the blood.

Alveolar Type I Cells

Alveolar type I cells are flat, squamous cells that line the alveoli and are responsible for gas exchange.

Alveolar Gas Equation

The alveolar gas equation is used to calculate the partial pressure of oxygen in the alveolus.
The value of the respiratory quotient (R) used in the alveolar gas equation is 0.8.
PIO2 represents the partial pressure of oxygen in the alveolus.
The formula for calculating PIO2 is PIO2 = Pio2 - (PACO2 / R).
PACO2 represents the partial pressure of carbon dioxide in the alveolus.
An increase in PACO2 occurs during hypoventilation, and a decrease in PACO2 occurs during hyperventilation.

Respiratory Gas Exchange

The equation used to calculate respiratory gas exchange (R) is R = (CO2 produced / O2 consumed).
The usual value of respiratory gas exchange (R) is 0.8.
The equation for calculating respiratory gas exchange (R) in terms of CO2 and O2 is R = (VCO2 / VO2).

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Description

Test your knowledge of Dalton's law of partial pressure and the equations used to measure dry and humidified gases. Understand how to calculate partial pressures based on barometric pressure, water vapor pressure, and fractional concentration.