Human Gas Exchange
Define gas exchange and name where it occurs in humans.
Gas exchange is the diffusion of O₂ into blood and CO₂ out of blood; it occurs in the alveoli.
What part of the gill increases surface area for gas exchange?
Gill filaments and lamellae
What are spiracles?
Openings for air to enter/exit
What makes alveolar and capillary walls good for gas exchange?
One cell thick; short diffusion path
What is counter-current flow?
Water and blood flow in opposite directions
What structures deliver air directly to cells?
Tracheae and tracheoles
Why is a moist lining important in alveoli?
It helps gases dissolve for diffusion
How does counter-current flow improve gas exchange?
Keeps a steep oxygen gradient across the whole lamella
How do insects move air through their bodies?
Body movements compress air sacs
How does ventilation help maintain a concentration gradient?
Brings in O₂ and removes CO₂
Name one structural feature of lamellae that helps gas exchange.
They are thin and contain capillaries
Why don't insects need blood for gas transport?
Air is delivered directly to cells through tracheae
Name and describe two alveolar adaptations that improve diffusion.
Large surface area; capillary network
What would happen if water and blood flowed in the same direction?
Gradient would disappear quickly; less O₂ diffuses
Compare how insects and humans maintain concentration gradients.
Insects: body movement; Humans: ventilation