November 5, 2024

A Level Biology Revision “Non-specific Defences Against Pathogens”

Author: Freesciencelessons via YouTube
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In this video, we start looking at the body’s non-specific defences against pathogens. These include the skin, mucous membranes, lysozyme and expulsive reflexes. In the next video, we look at blood clotting and inflammation.

Image credits:

Human Skin Structure
https://commons.wikimedia.org/wiki/File:Human_skin_structure.jpg
XenonR, CC BY 3.0 https://creativecommons.org/licenses/by-sa/3.0/deed.en

Tear
https://commons.wikimedia.org/wiki/File:Tear.jpg
NessaLand, CC BY 2.0 https://creativecommons.org/licenses/by/2.0, via Wikimedia Commons

Scab
https://commons.wikimedia.org/wiki/File:Hand_Abrasion_-_2_days_22_hours_12_minutes_after_injury.JPG
Jpbarrass, Public domain, via Wikimedia Commons

Sebaceous gland
https://commons.wikimedia.org/wiki/File:407_Sebaceous_Glands.jpg
OpenStax College, CC BY 3.0 https://creativecommons.org/licenses/by/3.0, via Wikimedia Commons

Epidermis and dermis
https://commons.wikimedia.org/wiki/File:Normal_Epidermis_and_Dermis_with_Intradermal_Nevus_10x-cropped.JPG
Normal_Epidermis_and_Dermis_with_Intradermal_Nevus_10x.JPG: Kilbadderivative work: Fama Clamosa, Public domain, via Wikimedia Commons

Lining of treachea
https://commons.wikimedia.org/wiki/File:Trachea_(mammal)_histology_cross-section.png
Magscope, CC BY-SA 4.0 https://creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons

Gastric mucosa
https://commons.wikimedia.org/wiki/File:Normal_gastric_mucosa_intermed_mag.jpg
Nephron, CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons

Sneeze
https://commons.wikimedia.org/wiki/File:Sneeze.JPG
James Gathany, Public domain, via Wikimedia Commons

Coughing
https://commons.wikimedia.org/wiki/File:Couging.jpg
https://upload.wikimedia.org/wikipedia/commons/0/01/Couging.jpg

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