IB Biology Topic D3.3.11 Changes in Blood Supply to Organs in Response to Changes in Activity Revision Notes (HL)

IB Biology Topic D3.3.11 Changes in Blood Supply to Organs in Response to Changes in Activity Revision Notes (HL) | RevisionDojo

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Arterioles Redirect Blood by Widening or Narrowing

Blood flow is redistributed by smooth muscle in the walls of arterioles.
1. Vasoconstriction is when this muscle contracts, narrowing the arteriole and reducing blood flow to the organ it supplies.
2. Vasodilation is when this muscle relaxes, widening the arteriole and increasing blood flow to the organ it supplies.
This redistribution matches supply to each organ's demand for oxygen and nutrients as activity changes.
The same vessels also change diameter to control body temperature, but that is a separate response covered under thermoregulation.

Note

These arteriole changes are controlled by the autonomic nervous system.
The hormone adrenaline reinforces the same pattern of flow.
Shunt vessels can bypass a capillary bed to redirect blood quickly between arterioles and venules.

Exercise Sends More Blood to Muscle and the Heart

During vigorous exercise, arterioles redirect blood toward the organs that need the most oxygen and glucose.
1. Skeletal muscle: flow increases sharply to deliver oxygen and glucose for ATP production and sustained contraction.
2. Heart: flow increases to fuel the harder, faster pumping of cardiac muscle.
3. Gut: flow decreases because digestion can wait until activity drops.
4. Kidneys: flow decreases, lowering the filtration rate and freeing blood for muscle.

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IB Biology Topic D3.3.11: Changes in Blood Supply to Organs in Response to Changes in Activity Notes

Arterioles Redirect Blood by Widening or Narrowing

Exercise Sends More Blood to Muscle and the Heart

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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Arterioles Redirect Blood by Widening or Narrowing

Exercise Sends More Blood to Muscle and the Heart

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

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

IB Biology Topic D3.3.11: Changes in Blood Supply to Organs in Response to Changes in Activity Notes

Arterioles Redirect Blood by Widening or Narrowing

Exercise Sends More Blood to Muscle and the Heart

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

Arterioles Redirect Blood by Widening or Narrowing

Exercise Sends More Blood to Muscle and the Heart

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

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics