Physiology Q2B4: Ventilation Flashcards

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Questions and Answers

How does anatomical dead space differ from physiological dead space?

There is no difference.

Anatomical dead space includes alveolar dead space.

Anatomical dead space refers to the volume of the lung not involved in gas exchange. (correct)

Physiological dead space refers to the volume of the lung not involved in gas exchange.

What can the Bohr equation be used to calculate?

Physiological dead space.

What three assumptions are made when using the Bohr equation to calculate physiological dead space?

All CO2 comes from alveolar gas (not dead space), arterial CO2 equals alveolar CO2, and conservation of mass.

What is minute ventilation a measure of?

Air volume inhaled over time (minute). Signup and view all the answers

What are the two components of minute ventilation?

Alveolar ventilation and dead space ventilation. Signup and view all the answers

If tidal volume increases, how will alveolar ventilation and dead space ventilation change?

Alveolar ventilation will increase while dead space ventilation will remain unchanged. Signup and view all the answers

If respiratory frequency increases, how will alveolar ventilation and dead space ventilation change?

Both alveolar ventilation and dead space ventilation will increase. Signup and view all the answers

Is increasing tidal volume or respiratory frequency more efficient in increasing alveolar ventilation? Why?

Increasing tidal volume is more efficient. Signup and view all the answers

What does the respiratory exchange ratio refer to?

Rate of CO2 expiration over rate of O2 reaching alveoli. Signup and view all the answers

How does respiratory exchange rate differ from respiratory quotient?

Respiratory exchange rate refers to a ratio at the respiratory level, while respiratory quotient refers to a ratio at the metabolic level. Signup and view all the answers

When does the respiratory exchange ratio equal the respiratory quotient?

At steady state. Signup and view all the answers

What effect does increasing alveolar ventilation have on alveolar CO2 pressure and O2 pressure?

Increases alveolar pressure of O2 and decreases alveolar pressure of CO2. Signup and view all the answers

What effect does an increase in metabolic activity have on the alveolar pressure of oxygen?

Increases in metabolic activity decrease the alveolar pressure of O2. Signup and view all the answers

What value is used to define hyper and hypoventilation? What does this value assess?

Alveolar pressure of CO2; it assesses if ventilation is appropriate to metabolic activity. Signup and view all the answers

What effect does hypothyroidism have on ventilation? What will this do to alveolar pressure of CO2?

Hypothyroidism decreases ventilation, causing alveolar pressure of CO2 to increase. Signup and view all the answers

What is the ideal alveolar gas equation used to measure?

The alveolar pressure of oxygen. Signup and view all the answers

What is the alveolar ventilation equation used to measure?

The alveolar pressure of carbon dioxide. Signup and view all the answers

What is the normal A-a difference range (mmHg) for pressure of oxygen? What is the normal a/A pressure ratio of oxygen?

A-a difference: 5-20 mmHg; a/A ratio: about 0.8. Signup and view all the answers

What is the clinical term for normal spontaneous breathing?

Eupnea. Signup and view all the answers

How does hyperpnea differ from hyperventilation?

Hyperpnea matches metabolic demands; hyperventilation does not. Signup and view all the answers

What is the clinical term for increased frequency of breathing? If tidal volume is also increased, what happens to alveolar ventilation?

Tachypnea; alveolar ventilation increases if tidal volume increases. Signup and view all the answers

A temporary absence of breathing which resumes spontaneously is referred to as what clinically?

Apnea. Signup and view all the answers

Study Notes

Anatomical vs. Physiological Dead Space

Anatomical dead space is the lung volume not involved in gas exchange.
Physiological dead space includes anatomical dead space plus any non-functioning alveoli (alveolar dead space).

Bohr Equation

Used to calculate physiological dead space.
Assumes all CO2 originates from alveolar gas, arterial CO2 equals alveolar CO2, and conservation of mass holds true.

Minute Ventilation

Represents the volume of air inhaled per minute.
Calculated as the product of tidal volume (TV) and respiratory frequency (f).

Components of Minute Ventilation

Consists of alveolar ventilation and dead space ventilation.

Effects of Tidal Volume and Respiratory Frequency

Increasing tidal volume boosts alveolar ventilation; dead space ventilation remains unchanged.
Increasing respiratory frequency elevates both alveolar ventilation and dead space ventilation.

Efficiency of Increasing Alveolar Ventilation

Increasing tidal volume is more efficient for enhancing alveolar ventilation than increasing respiratory frequency since the latter also increases dead space ventilation.

Respiratory Exchange Ratio (RER)

Defined as the rate of CO2 expiration to the rate of O2 reaching the alveoli, typically less than one.

Respiratory Exchange Ratio vs. Respiratory Quotient

RER indicates the CO2 to O2 ratio at the respiratory level (expired vs. inhaled).
Respiratory quotient refers to the CO2 to O2 ratio at the metabolic level (produced vs. used).

Steady State Relationship

RER equals respiratory quotient when in steady state.

Effects of Increased Alveolar Ventilation

Raises alveolar O2 pressure while reducing alveolar CO2 pressure.

Impact of Metabolic Activity on Alveolar Pressure

An increase in metabolic activity results in a decline of alveolar O2 pressure.

Hyperventilation and Hypoventilation Definition

Defined by alveolar CO2 pressure; assesses adequacy of ventilation relative to metabolic activity.

Impact of Thyroid Function on Ventilation

Hyperthyroidism escalates ventilation rates, decreasing alveolar CO2 pressure.

Alveolar Gas Equations

Ideal alveolar gas equation determines alveolar pressure of oxygen.
Alveolar ventilation equation assesses alveolar pressure of carbon dioxide.

Normal Ranges for A-a Difference

The normal A-a difference for oxygen pressure is 5-20 mmHg.
Normal a/A pressure ratio for oxygen is approximately 0.8.

Clinical Terms

Eupnea refers to normal spontaneous breathing.
Tachypnea denotes an increased breathing rate; if tidal volume rises, alveolar ventilation also increases.
Apnea describes a temporary absence of breathing that resumes spontaneously.

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Description

Test your knowledge on key concepts related to ventilation in physiology with these flashcards. Cover topics such as anatomical and physiological dead space, including the Bohr equation and its calculations. Perfect for students looking to reinforce their understanding of respiratory function.