IMMUNOLOGY: FIRST LINE OF DEFENSE

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1,2Strategic attack is very important in every battle. This is why even the body places certain infantry in the first line of defense to fight intruders (pathogens) from entering and upon their entry into the body. Pathogens are disease-causing microorganisms.

The body has strategically placed two barriers to prevent the entry of pathogens into the body and also eliminate them as fast as possible upon their entry into the body.

These barriers include:

  1. c

Physical barrier

The physical barriers include:

  • The skin
  • The mucus
  • Urethra
  • Cilia (Hair)
  • Urine flow

Skin

The external covering of the body, also known as the skin forms a thick barrier layer that prevents the entry of microorganism from entering into the body.

Mucus

This is slimy and slippery polysaccharide found primarily in the nostril, ear and genital region of the body. Mucus contains lysozyme and antibodies that act against the survival and growth of microorganisms (bacteria and fungi

Cilia (hair)

Cilia or hair on the airway and at the entry of the ear also trap the pathogenic microorganisms and dust from entering the lung and inner ear

Urine flow

The urine also helps to flush out pathogenic microorganisms out of the urethra.

Chemical barrier

  • Lysozyme
  • Gastric juice
  • Lactoferrin

Lysozyme

This is a hydrolytic enzyme found tears, saliva, and sweat on the skin. It helps to breakdown the complex polysaccharide structure on the cell wall of microbes, thereby leading to the death of the pathogenic microorganisms.

Gastric juice

The gastric juice in the human stomach is acidic in nature. It contains Hydrochloric acid (HCL). This makes the stomach uninhabitable for certain microorganisms and thus leading to their death.

Lactoferrin

This is another first line of defense antimicrobial substance ingested in breast milk by newborn babies. This substance helps new babies to stay strong till their immune system is fully formed.

See also introduction to immunology

Cite this article as: Fagbohun, S.O., "IMMUNOLOGY: FIRST LINE OF DEFENSE," in ATG Ventures, 01/02/2019, https://atgventure.com/immunology-first-line-of-defense/.

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Bibliography

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1.
Foundation C-12. | CK-12 Foundation. CK-12 Foundation. https://www.ck12.org/book/CBSE_Biology_Book_Class_XII/section/11.8/. Accessed February 1, 2019.
2.
First Line of Defence | Brent Cornell. Bioninja. http://www.vce.bioninja.com.au/aos-2-detecting-and-respond/defence-against-disease/first-line-of-defence.html. Accessed February 1, 2019.
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