IB Biology Topic B3.1.5 Ventilation of the Lungs Revision Notes (SL/HL)

IB Biology Topic B3.1.5 Ventilation of the Lungs Revision Notes (SL/HL) | RevisionDojo

Written by official IB examiners

Ventilation Moves Air by Changing Pressure Inside the Chest

Ventilation is the process of moving air in and out of the lungs.
Muscles change the volume of the chest, which changes the pressure inside it, and air flows to even the pressure out.
This follows a simple rule: when volume goes up, pressure goes down, and when volume goes down, pressure goes up (Boyle's law).
Ventilation has two phases:
1. Inspiration: air is drawn into the lungs.
2. Expiration: air is pushed out of the lungs.

Constantly refreshing the air keeps oxygen high and carbon dioxide low in the alveoli, so the diffusion gradient stays steep.

Ventilation of the lungs

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Analogy

Think of your chest as a syringe.
Pull the plunger out and air rushes in.
Push the plunger in and air is forced out.

The Diaphragm Is the Main Driver of Quiet Breathing

The diaphragm is a large, dome-shaped muscle that separates the chest cavity from the abdomen.
It drives ventilation by changing the volume of the chest:

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Ventilation Moves Air by Changing Pressure Inside the Chest

Ventilation is the process of moving air in and out of the lungs.
Muscles change the volume of the chest, which changes the pressure inside it, and air flows to even the pressure out.
This follows a simple rule: when volume goes up, pressure goes down, and when volume goes down, pressure goes up (Boyle's law).
Ventilation has two phases:
1. Inspiration: air is drawn into the lungs.
2. Expiration: air is pushed out of the lungs.

Constantly refreshing the air keeps oxygen high and carbon dioxide low in the alveoli, so the diffusion gradient stays steep.

Ventilation of the lungs

Open in new tab

Analogy

Think of your chest as a syringe.
Pull the plunger out and air rushes in.
Push the plunger in and air is forced out.

The Diaphragm Is the Main Driver of Quiet Breathing

The diaphragm is a large, dome-shaped muscle that separates the chest cavity from the abdomen.
It drives ventilation by changing the volume of the chest:

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

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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.

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.

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A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

IB Biology Topic B3.1.5: Ventilation of the Lungs Notes

Ventilation Moves Air by Changing Pressure Inside the Chest

The Diaphragm Is the Main Driver of Quiet Breathing

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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Ventilation Moves Air by Changing Pressure Inside the Chest

The Diaphragm Is the Main Driver of Quiet Breathing

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