Concentration Gradient

What is essential for maintaining gas exchange as a passive process?

Concentration gradients must be maintained at gas exchange surfaces.

What factors maintain a concentration gradient?

• dense networks of blood vessels

• continuous blood flow

• ventilation

• ventilation (lungs)

• water movement (for gills)

Dense networks of blood vessels

How many kilometers of blood vessels does an average adult have?

Approximately 100,000 kilometers of blood vessels.

What role does continuous blood flow play in gas exchange?

It helps replenish the concentration gradient by removing substances that have recently diffused across the exchange surface.

What does continuous blood flow maintain?

A higher concentration of those substances in the external environment

What is ventilation in the context of gas exchange?

The movement of air across an exchange surface to replenish gas supply and maintain concentration gradients.

What does ventilation enable in human lungs?

It ensures a continuous supply of oxygen-rich air to the alveoli and facilitates the removal of CO2.

How do aquatic organisms extract dissolved oxygen?

By actively moving water over their gills using movements of their mouths and opercula.

What is the countercurrent exchange system?

A system where water flows over the gills in a direction opposite to the flow within the gill filaments.