IB Biology Topic B3.1.4 Adaptations of Mammalian Lungs for Gas Exchange Revision Notes (SL/HL)

IB Biology Topic B3.1.4 Adaptations of Mammalian Lungs for Gas Exchange Revision Notes (SL/HL) | RevisionDojo

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Mammalian Lungs Pack a Huge, Thin, Well-Supplied Surface Into a Small Space

Mammalian lungs are built around millions of tiny air sacs called alveoli (singular: alveolus), the sites of gas exchange.
Air reaches them through branching airways: the trachea, bronchi, and bronchioles.
Together these features give a large surface area and a short diffusion distance, the two things gas exchange depends on most.

A Huge Alveolar Surface Speeds Up Gas Exchange

Each lung holds around 300 million alveoli, giving a total surface area of about 70 m², roughly the size of a tennis court.
A large surface area lets more oxygen enter the blood and more carbon dioxide leave it at the same time.

The bigger the surface, the faster gases can diffuse across it.

Analogy

Picture the alveoli as tiny bubbles in a foam.
The more bubbles you pack in, the greater the total surface touching the air.

Thin Type I Pneumocytes Give the Shortest Possible Diffusion Path

The alveolar wall is made mainly of type I pneumocytes, extremely thin cells specialised for gas exchange.
The alveolar wall and the wall of the surrounding capillary are each only one cell thick.
This thin barrier lets oxygen and carbon dioxide cross quickly.

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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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Mammalian Lungs Pack a Huge, Thin, Well-Supplied Surface Into a Small Space

Mammalian lungs are built around millions of tiny air sacs called alveoli (singular: alveolus), the sites of gas exchange.
Air reaches them through branching airways: the trachea, bronchi, and bronchioles.
Together these features give a large surface area and a short diffusion distance, the two things gas exchange depends on most.

A Huge Alveolar Surface Speeds Up Gas Exchange

Each lung holds around 300 million alveoli, giving a total surface area of about 70 m², roughly the size of a tennis court.
A large surface area lets more oxygen enter the blood and more carbon dioxide leave it at the same time.

The bigger the surface, the faster gases can diffuse across it.

Analogy

Picture the alveoli as tiny bubbles in a foam.
The more bubbles you pack in, the greater the total surface touching the air.

Thin Type I Pneumocytes Give the Shortest Possible Diffusion Path

The alveolar wall is made mainly of type I pneumocytes, extremely thin cells specialised for gas exchange.
The alveolar wall and the wall of the surrounding capillary are each only one cell thick.
This thin barrier lets oxygen and carbon dioxide cross quickly.

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 B3.1.4: Adaptations of Mammalian Lungs for Gas Exchange Notes

Mammalian Lungs Pack a Huge, Thin, Well-Supplied Surface Into a Small Space

A Huge Alveolar Surface Speeds Up Gas Exchange

Thin Type I Pneumocytes Give the Shortest Possible Diffusion Path

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

Mammalian Lungs Pack a Huge, Thin, Well-Supplied Surface Into a Small Space

A Huge Alveolar Surface Speeds Up Gas Exchange

Thin Type I Pneumocytes Give the Shortest Possible Diffusion Path

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