Gas exchange Flashcards
What is gas exchange?
O2 is transported to the cells and CO2 is transported away from the cells.
How do gases move in and out of the lungs?
By breathing.
What process allows O2 and CO2 to be exchanged in the lungs?
Diffusion.
How are gases dissolved in the blood transported?
By the circulatory system.
What does optimal gas exchange mean?
The tissue’s needs for oxygen are met and the requirement of CO2 to be removed is met.
What can impaired gas exchange lead to?
Hypoxia and cell injury.
What is cessation of gas exchange associated with?
Anoxia and cell death.
What are the components of normal respiratory function?
Alveolar ventilation, alveolar perfusion, alveolar-capillary diffusion, gas transport in the circulation.
What does ventilation refer to?
The act of driving air in and out of the lungs.
What factors affect ventilation?
Chest wall compliance and respiratory muscle function.
What is lung compliance?
The ability of the lungs to expand.
What is tidal volume?
The air you breathe in and out at rest (~500mL).
What is vital capacity?
Expiratory volume + tidal volume + inspiratory capacity.
What does forced expiratory volume measure?
% of vital capacity exhaled over time.
What indicates an obstructive pulmonary disorder?
Inability to exhale 75-85% of vital capacity in one second.
What factors affect alveolar-capillary diffusion?
Permeability, surface area, concentration gradient.
What is the normal partial pressure of oxygen in arterial blood (PaO2)?
80 mm Hg.
How is CO2 primarily transported in the blood?
In the form of bicarbonate ion.
What is the normal partial pressure of CO2 in arterial blood?
35-45 mmHg.
What do central chemoreceptors measure?
PCO2 and pH in cerebrospinal fluid.
What triggers faster and deeper breathing?
Increased PCO2 or decreased pH.
What do peripheral chemoreceptors measure?
PO2 in arterial blood.
What happens when PO2 is less than 60 mm Hg?
Respiration increases.
True or False: High CO2 or low O2 drives ventilation.
True.
What are the consequences of impaired gas exchange?
Increased work of breathing, hypoxemia, hypercapnia, hypoxic cell injury.
What age-related changes affect older adults’ respiratory function?
Decreased elasticity, higher chance of respiratory infections.
What conditions impair gas transport in blood?
Anemia, hypertension, blood loss, any impairment of perfusion.
What conditions affect alveolar-capillary diffusion?
Pulmonary edema, COPD, pneumonia.
What conditions can impair ventilation?
COPD, asthma, muscle weakness, rib fracture, neuromuscular disorders, chest cage deformities.
What happens to chemoreceptors in a patient with chronically elevated blood levels of CO2?
They become desensitized over time.
