Muscles of Breathing
What muscle is primarily responsible for quiet, resting inspiration?
Diaphragm
What is the normal volume of air moved in and out during quiet breathing called?
Tidal volume (TV)
What does FEV₁ measure?
Air exhaled in the first second of forced expiration
What is the most important buffer system in blood?
Carbonic acid–bicarbonate buffer system
Where does external respiration occur?
In the alveoli of the lungs
Which muscles lift the ribs slightly during normal inspiration?
External intercostal muscles
What volume of air remains in the lungs after maximal exhalation?
Residual volume (RV)
What does FVC measure?
Total volume of air forcibly exhaled after deep inhalation
What enzyme converts CO₂ and water into carbonic acid in red blood cells?
Carbonic anhydrase
In systemic tissues, which gas moves from blood into cells?
Oxygen
Name ONE accessory muscle used during forced inspiration.
Sternocleidomastoid, scalenes, or pectoralis minor
What is vital capacity made of?
TV + IRV + ERV
What does the FEV₁/FVC ratio tell us about airflow?
How much air can be exhaled in the first second compared to total exhaled air
What two ions are produced when carbonic acid dissociates?
Bicarbonate (HCO₃⁻) and hydrogen (H⁺)
What drives gas exchange in both lungs and tissues?
Diffusion down concentration gradients.
Which muscle group pushes the diaphragm upward during forced expiration?
Abdominal muscles
What lung volume prevents the lungs from collapsing?
Residual volume
After using a bronchodilator (such as albuterol), what would you expect to happen to the FEV₁/FVC ratio in someone with asthma?
It would increase (move closer to normal)
How does the body remove excess acid using this buffer system?
By converting it into CO₂ and exhaling it
Name one feature that makes alveoli efficient for gas exchange.
Thin walls, moisture, or dense capillary networks
Why do people with asthma often use their neck muscles when breathing?
They are recruiting accessory muscles due to difficulty moving air
What is total lung capacity equal to?
Vital capacity + residual volume
Why does the FEV₁/FVC ratio improve after a bronchodilator in asthma?
Because the airways open up, allowing more air to be exhaled in the first second
How does breathing contribute to our bodies acid–base regulation?
Because removing CO₂ removes acid from the body
Why does carbon dioxide move from blood into alveoli?
Because CO₂ concentration is higher in blood than in alveoli