Physiology Chapter 13 Flashcards

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Questions and Answers

If Patm = 0 mmHg and Palv = -2 mmHg, what is happening?

Air is flowing out of the lungs

Air is flowing into the lungs (correct)

Lungs are collapsing

There is no airflow

Transpulmonary pressure increases by 3 mmHg during a normal inspiration. Which of the following is true?

The compliance of the lung of subject A is less than that of subject B

Both subjects have the same lung compliance

The compliance of the lung of subject B is less than that of subject A (correct)

Neither subject has compliance issues

Which of the following will increase alveolar PO2?

Decreased alveolar ventilation

Increased atmospheric pressure

Increased alveolar ventilation with no change in metabolism (correct)

Increased metabolism

Which of the following will cause the largest increase in systemic arterial oxygen saturation in the blood?

An increase in arterial PO2 from 40 to 60 mmHg Signup and view all the answers

In arterial blood with a PO2 of 60 mmHg, which of the following situations will result in the lowest blood oxygen saturation?

Elevated body temperature, acidosis, and increased DPG Signup and view all the answers

Peripheral and central chemoreceptors both increase firing when arterial PCO2 increases.

True Signup and view all the answers

If a patient is unable to produce surfactant, will her intrapleural pressure have to be more or less subatmospheric during inspiration compared to a healthy person?

More subatmospheric Signup and view all the answers

Why must a person floating on the surface of the water and breathing through a snorkel increase his tidal volume and/or breathing frequency?

To offset additional dead space from the snorkel Signup and view all the answers

Are the new steady-state values of alveolar P O2 and P CO2 after a healthy person doubles their alveolar ventilation higher or lower than normal?

Higher P O2 and lower P CO2 Signup and view all the answers

Could hypoventilation due to respiratory muscle weakness cause alveolar PO2 to be higher than normal?

False Signup and view all the answers

Will a person's thickened alveolar membranes necessarily result in low arterial PO2 at rest?

Not at rest Signup and view all the answers

How much will the oxygen content of arterial blood increase when a person is breathing 100% oxygen compared to room air?

Only a few percent Signup and view all the answers

Which of the following have higher values in systemic venous blood than in systemic arterial blood?

All of the above Signup and view all the answers

What is the ventilation pattern in patients with severe uncontrolled type 1 diabetes mellitus?

Profound hyperventilation Signup and view all the answers

Study Notes

Airflow and Lung Compliance

Negative alveolar pressure (Palv = -2 mmHg) relative to atmospheric pressure (Patm = 0 mmHg) indicates that air flows into the lungs.
During normal inspiration, transpulmonary pressure can increase by 3 mmHg, affecting lung volume compliance: subject A with 500 mL inspired demonstrates greater compliance than subject B with 250 mL.

Alveolar Gas Dynamics

Increased alveolar ventilation without changes in metabolism raises alveolar PO2.
A significant rise in systemic arterial oxygen saturation occurs when arterial PO2 increases from 40 to 60 mmHg due to the steep portion of the oxygen-hemoglobin dissociation curve.

Factors Affecting Oxygen Saturation

Low arterial blood oxygen saturation at PO2 of 60 mmHg can arise from elevated temperature, acidosis, and increased 2,3-DPG, which shift the oxygen-hemoglobin curve downward.
Both peripheral and central chemoreceptors respond to increased arterial PCO2, triggering enhanced respiratory ventilation due to respiratory acidosis.

Surfactant and Intrapleural Pressure

A patient lacking surfactant requires a more subatmospheric intrapleural pressure during inspiration, due to decreased lung compliance needing greater transpulmonary pressure for inflation.

Ventilation Adjustments

An individual using a snorkel must increase tidal volume and/or breathing frequency to maintain adequate alveolar ventilation, as snorkel volume adds to dead space.
Following a doubling of alveolar ventilation, P O2 increases while P CO2 decreases compared to normal values.

Hypoventilation and Discrepancies in Gas Levels

In cases where alveolar PO2 is normal yet arterial PO2 is low, hypoventilation is not the cause; instead, potential issues include diffusion impairment, shunting, or ventilation-perfusion mismatches.

Diffusion and Blood Gas Exchange

Thickened alveolar membranes may not lead to low arterial PO2 at rest; however, during exercise, reduced diffusion time increases the likelihood of unequal equilibration, resulting in lower arterial PO2.

Oxygen Content in Blood

Breathing 100% oxygen only marginally increases arterial blood oxygen content due to hemoglobin already being nearly saturated at normal room air levels.

Metabolism and Venous Blood Composition

Systemic venous blood exhibits higher levels of plasma PCO2, erythrocyte PCO2, bicarbonate concentrations, hydrogen ion concentrations, and carbamino concentrations compared to arterial blood, due to metabolic byproducts.

Ventilation in Diabetes Patients

Type 1 diabetes patients often experience profound hyperventilation leading to increased arterial PO2 and decreased arterial PCO2, triggered by elevated hydrogen ion concentrations from organic acid production.

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Description

Test your knowledge on respiratory physiology with this set of flashcards covering Chapter 13 concepts. Explore topics such as air flow dynamics and transpulmonary pressure changes during inspiration. Ideal for students looking to reinforce their understanding of lung mechanics.