R2 - Respiratory Functions Flashcards
What happens during inhalation?
• Rib cage moves up and outward
• Diaphragm moves down
• Thoracic cavity volume increases
• Lung pressure decreases, air flows in
What happens during exhalation?
• Rib cage moves down and inward
• Diaphragm moves up
• Thoracic cavity volume decreases
• Lung pressure increases, air is pushed out
Where does external respiration occur?
In the alveoli and capillaries.
How does oxygen move into the blood?
By diffusion, from high concentration in air to low concentration in blood.
What is facilitated diffusion in gas exchange?
About 30% of oxygen is transported using channel proteins in the alveoli membrane.
How is oxygen transported in the blood?
• 99% by hemoglobin
• 1% in blood plasma
How is carbon dioxide transported in the blood?
• 23% binds to hemoglobin
• 7% dissolves in blood plasma
• 70% is converted into bicarbonate ions (HCO₃⁻)
What role do chemoreceptors play in breathing?
• CO₂ chemoreceptors (very sensitive) detect CO₂ and pH changes → increase breathing rate
• O₂ chemoreceptors (less sensitive, backup system) detect low O₂ levels
How does CO₂ affect blood pH?
• CO₂ + H₂O → Carbonic acid (H₂CO₃)
• Carbonic acid breaks into H⁺ and bicarbonate (HCO₃⁻)
• More H⁺ makes blood acidic, triggering chemoreceptors to increase breathing rate
What does a spirograph measure?
Air movement in and out of the lungs per second.
What is tidal volume?
The amount of air exchanged in normal breathing.
What is inspiratory reserve volume?
Extra air that can be inhaled beyond tidal volume.
What is expiratory reserve volume?
Extra air that can be exhaled beyond tidal volume.
What is vital capacity?
The total amount of air that can be inhaled and exhaled.
What is residual volume?
Air remaining in lungs after exhalation, preventing lung collapse.
