IB Biology Topic B3.1.3 Maintenance of Concentration Gradients at Exchange Surfaces in Animals Revision Notes (SL/HL)

IB Biology Topic B3.1.3 Maintenance of Concentration Gradients at Exchange Surfaces in Animals Revision Notes (SL/HL) | RevisionDojo

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A Steep Concentration Gradient Keeps Diffusion Going

Definition

Concentration Gradient

The difference in concentration of a substance (e.g., oxygen or carbon dioxide) between two regions.

Gas exchange happens by diffusion, so gases move from high to low concentration.
Diffusion only continues if a concentration gradient is kept up: oxygen stays higher in the lungs than in the blood, and carbon dioxide stays higher in the blood than in the lungs.
Animals keep these gradients steep using two active processes: continuous blood flow and ventilation.

Note

If gases were left to sit, both sides would reach equal concentration and diffusion would stop.
Maintaining the gradient is what keeps oxygen flowing in and carbon dioxide flowing out.

Dense Capillary Networks Carry Gases Away Fast

Gas-exchange surfaces such as the alveoli and gills are wrapped in dense networks of blood vessels.
These networks carry oxygen away from the surface quickly and bring carbon dioxide to it for removal.
By taking oxygen away and delivering carbon dioxide, the blood keeps a difference in gas concentrations across the surface.
That constant difference keeps diffusion fast.

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Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

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A Steep Concentration Gradient Keeps Diffusion Going

Definition

Concentration Gradient

The difference in concentration of a substance (e.g., oxygen or carbon dioxide) between two regions.

Gas exchange happens by diffusion, so gases move from high to low concentration.
Diffusion only continues if a concentration gradient is kept up: oxygen stays higher in the lungs than in the blood, and carbon dioxide stays higher in the blood than in the lungs.
Animals keep these gradients steep using two active processes: continuous blood flow and ventilation.

Note

If gases were left to sit, both sides would reach equal concentration and diffusion would stop.
Maintaining the gradient is what keeps oxygen flowing in and carbon dioxide flowing out.

Dense Capillary Networks Carry Gases Away Fast

Gas-exchange surfaces such as the alveoli and gills are wrapped in dense networks of blood vessels.
These networks carry oxygen away from the surface quickly and bring carbon dioxide to it for removal.
By taking oxygen away and delivering carbon dioxide, the blood keeps a difference in gas concentrations across the surface.
That constant difference keeps diffusion fast.

Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

IB Biology Topic B3.1.3: Maintenance of Concentration Gradients at Exchange Surfaces in Animals Notes

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

A Steep Concentration Gradient Keeps Diffusion Going

Dense Capillary Networks Carry Gases Away Fast

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

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A Steep Concentration Gradient Keeps Diffusion Going

Dense Capillary Networks Carry Gases Away Fast

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account