Innate immunity: The first line of defense against pathogens

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What Is the Innate Immune System?

Humans and animals are constantly exposed to a variety of foreign particles and infectious agents such as bacteria, viruses, fungi and other parasites. It has been noticed that if a person suffers from certain diseases, for example, measles, the same disease does not attack him again because he is immune to that disease.

The system that protects body from various infections and diseases is termed as body immune system. However, the term innate immune system refers to the mechanisms used by the body to protect against all environmental agents, which may include food items, chemicals, drugs, diseases and others.

Innate immunity is the body’s own immune system, which is always available to protect the body. When pathogens enter into the body, they are quickly attacked by the components of the defense system and are killed at the same time. This is the first line of defense in most plants and animals.

Innate immunity consists of four kinds of barriers, which are mentioned below:

  1. Anatomical

  2. Physiological

  1. Phagocytic

  2. Inflammatory barriers

Innate Immunity Barriers:

Anatomical barriers: These defense mechanisms block the entry of the pathogens into the body. They are skin and mucous membranes – mucous entraps foreign pathogens and cilia propel them out of the body.

Physiological barriers: These include body temperature; pH and other body secretions that prevent growth of any microorganisms entering into the body. For example, body temperature i.e., fever, prevents the growth of pathogens and acidic atmosphere in the stomach do the same. Moreover, lysozymes, which is present in tears digest bacterial cell wall and kill them. And when viruses attack the body tissues, interferons present in cells protect the body tissues. .

Phagocytic barriers: It is one of the most important defense mechanisms in innate immunity. Humans contain phagocytes that circulate in the body – the most important phagocytes are macrophages and neutrophils. These phagocytes engulf microbes, viruses, cellular debris, etc.

Inflammatory response: When a pathogen attacks and the site of infection becomes red – the infected area swells and the temperature also rises. This kind of response is known as inflammatory response. Such response occurs due to the release of chemical alarm signals such as histamine and prostaglandins by the damaged mast cells. Serum proteins are also released from the blood vessels. Pahgocytic cells are also present in the affected area that helps destroy the invading pathogens.

Reference Section

Pathmicro. “IMMUNOLOGY - CHAPTER ONE, INNATE (NON-SPECIFIC) IMMUNITY.” Retrieved on December 1, 2008 from Innate (non specific) immunity.