gas exchange notes

Question 1

What do chemoreceptors in the medulla sense?

Answer 1

PaCO2 too high

Chemoreceptors are sensitive to changes in carbon dioxide levels and play a crucial role in regulating respiration.

Question 2

What is the percentage of O2 pulled in from the atmosphere?

Answer 2

21% O2

This is the standard concentration of oxygen in the Earth’s atmosphere.

Question 3

What is the function of alveolar I cells?

Answer 3

Provide structure

Alveolar I cells are thin and facilitate gas exchange in the lungs.

Question 4

What do alveolar II cells produce?

Answer 4

Surfactant

Surfactant reduces surface tension in the alveoli, preventing collapse and aiding in lung function.

Question 5

What happens to O2 in the alveoli?

Answer 5

It diffuses into pulmonary capillaries

The high pressure of oxygen in the alveoli drives diffusion into the blood.

Question 6

How is oxygen measured in plasma?

Answer 6

Partial pressure of O2 in artery (PaO2)

PaO2 indicates how much oxygen is dissolved in the blood plasma.

Question 7

What is measured by the saturation of arterial hemoglobin?

Answer 7

Oxygen attached to hemoglobin (SaO2)

SaO2 reflects the percentage of hemoglobin that is saturated with oxygen.

Question 8

What happens when PaCO2 is low?

Answer 8

Turns OFF signals to medulla to initiate inhalation

Low carbon dioxide levels can indicate adequate ventilation, reducing the need for further inhalation.

Question 9

What age-related changes occur in older adults regarding alveoli?

Answer 9

Less elastic

Aging affects the elasticity of alveoli, impacting respiratory efficiency.

Question 10

What happens to respiratory muscles in older adults?

Answer 10

Diminished strength

Reduced muscle strength leads to lower maximum inspiratory and expiratory force.

Question 11

What is the consequence of reduced RBCs in older adults?

Answer 11

Anemia

Anemia results from a decrease in red blood cell production, affecting oxygen transport.

Question 12

What is a mild consequence of reduced oxygen availability?

Answer 12

Fatigue

Fatigue encourages the body to rest, reducing oxygen demand.

Question 13

What is a medium consequence of reduced oxygen availability?

Answer 13

Reduced mitochondrial respiration and oxidative metabolism

This can lead to respiratory acidosis due to inefficient gas exchange.

Question 14

What severe consequence can occur from reduced oxygen availability?

Answer 14

Cellular ischemia, necrosis, death

Severe oxygen deprivation can lead to critical cellular damage and death.

Question 15

What factors affect the ease of ventilation?

Answer 15

Resistance of airways and lung compliance

Both airway resistance and lung compliance are crucial for effective ventilation.