IB Biology Topic C3.2.2 Skin and Mucous Membranes as a Primary Defence Revision Notes (SL/HL)

IB Biology Topic C3.2.2 Skin and Mucous Membranes as a Primary Defence Revision Notes (SL/HL) | RevisionDojo

Written by official IB examiners

Skin and Mucous Membranes Are Your First Line of Defence

Pathogens surround you all the time, but two structures keep most of them out: skin and mucous membranes.
They form the first line of defence, a non-specific barrier that blocks pathogens before they ever get inside.

Analogy

The skin is a fortress wall.
Mucous membranes are sticky nets that trap invaders.

Skin Blocks Pathogens With Both Physical and Chemical Barriers

Physical Barrier

The outer layer of skin, the epidermis, is made of dead cells packed with the tough protein keratin.
This layer is waterproof and hard to penetrate, so pathogens cannot easily enter.
The skin also sheds dead cells, carrying away any pathogens stuck to the surface.

Note

Constant shedding means the skin surface is always being renewed.

Chemical Barrier

The sebaceous glands secrete sebum, which contains antimicrobial substances that slow bacterial growth.

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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 nisi ut aliquip ex ea commodo consequat.

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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Skin and Mucous Membranes Are Your First Line of Defence

Pathogens surround you all the time, but two structures keep most of them out: skin and mucous membranes.
They form the first line of defence, a non-specific barrier that blocks pathogens before they ever get inside.

Analogy

The skin is a fortress wall.
Mucous membranes are sticky nets that trap invaders.

Skin Blocks Pathogens With Both Physical and Chemical Barriers

Physical Barrier

The outer layer of skin, the epidermis, is made of dead cells packed with the tough protein keratin.
This layer is waterproof and hard to penetrate, so pathogens cannot easily enter.
The skin also sheds dead cells, carrying away any pathogens stuck to the surface.

Note

Constant shedding means the skin surface is always being renewed.

Chemical Barrier

The sebaceous glands secrete sebum, which contains antimicrobial substances that slow bacterial growth.

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 C3.2.2: Skin and Mucous Membranes as a Primary Defence Notes

Skin and Mucous Membranes Are Your First Line of Defence

Skin Blocks Pathogens With Both Physical and Chemical Barriers

Physical Barrier

Chemical Barrier

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

Skin and Mucous Membranes Are Your First Line of Defence

Skin Blocks Pathogens With Both Physical and Chemical Barriers

Physical Barrier

Chemical Barrier

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