Topic 11: Gas exchange in humans Flashcards
(26 cards)
What are the main parts of the human breathing system?
Lungs, diaphragm, ribs, intercostal muscles, larynx, trachea, bronchi, bronchioles, alveoli, and associated capillaries.
What is the function of the cartilage in the trachea?
Prevents collapse and keeps the airway open.
What is the function of the ribs?
Protect organs and help with breathing by moving the chest wall.
What do intercostal muscles do?
Help move the chest wall during breathing.
What is the role of the diaphragm?
Changes volume and pressure in the thorax to allow ventilation.
Why must gas exchange surfaces be thin?
For a short diffusion distance.
Why is a large surface area important for gas exchange?
More diffusion can happen at the same time.
Why is good ventilation important?
Maintains steep concentration gradients for O₂ and CO₂.
Why is a good blood supply important?
Moves gases quickly to and from cells.
Why must gas exchange surfaces be moist?
Gases dissolve first before diffusing.
What is the oxygen percentage in inspired air?
21%
What is the oxygen percentage in expired air?
16%
What is the carbon dioxide percentage in inspired air?
0.04%
What is the carbon dioxide percentage in expired air?
4%
How does water vapour compare in inspired and expired air?
Expired air has more water vapour.
What stays the same in inspired and expired air?
Nitrogen (78%)
What happens to limewater if carbon dioxide is present?
It turns cloudy.
What happens during inspiration (breathing in)?
External intercostal muscles contract, diaphragm contracts and moves down, thorax volume increases, pressure decreases, and air enters.
What happens during expiration (breathing out)?
External intercostal muscles relax, diaphragm relaxes into dome shape, thorax volume decreases, pressure increases, and air exits.
What muscles are used during coughing and sneezing?
Internal intercostal muscles.
How does physical activity affect breathing rate and depth?
Increases both.
Why does physical activity increase breathing rate?
More CO₂ in blood is detected by the brain, which increases breathing to remove it.
What device is used to measure breathing changes?
Spirometer (produces a spirogram).
Why is increased breathing important during exercise?
To supply more oxygen and remove more carbon dioxide from respiring tissues.
