Question

1.   Based on your understanding of the innate immune system list 3 broad categories (and AT LEAST ONE specific example in each category) that constitute the first line of defense mechanisms by the innate immune system. (Give an approximate time line for this type of defense)
2.   If this defense system is breached describe the process that follows (second line of innate defense). Explain how pathogens are detected and dealt with at this time with specific pathogen groups in mind, innate immune cells and molecular components involved. (Give an approximate timeline for this response)
3.   What are the TWO possible outcomes of this response and the way forward?

Answer 1

Answer:

1):

• Innate immunity is a non specific defence mechanism that acts immediately after the entry of pathogen in the body.
• It is an inborn mechanism and is not accquired.It includes physical barriers,chemical barriers and the immune system in the body.
• The first line of defence by the innate immunity includes the physical and chemical barriers.
• The mechanism of innate immunity is causing inflammation,phagocytosis,target cell lysis,autophagy etc.

The first line defence in innate immunity includes:

Physical barriers:-

• This include all lining of the body that prevents the entry of the pathogen.It includes skin(It is the largest mechanical barrier.
• No microorganism can enter without breaking the skin), hairs in the nasal cavity,gastrointestinal tract,cilia in the respiratory tract,cornea of eyes etc.

Secretions:-

• These are the secretions that has ability to suppress or kill the pathogen.It includes saliva in mouth .
• It contains an enzyme lysozyme that can destroy bacteria,Acid in the stomach,Mucous lining of tracts,tears

Beneficial bacteria:-

• Beneficial bacteria in th bowel ,mouth ,gut can control the invading bacteria.

2):

• If the invading microorganisms overcome the first line defence mechanism and enters the body ,the second line defence mechanism gets activated.
• This includes cells like neutrophils,T helper cells,killer T cells,macrophages,dendritic cells,B cells and suppressor T cells.
• Neutrophils primarily attack the foreign particles.
• Helper T cells are specific to pathogen .They give instructions through signals.
• Killer T cells kill pathogen by lysis.Macrophages eat the bacterial cells.Dendritic cells notifies the presence of bacterias to the T cells.
• B cells produce antibodies and serve as memory cells.Suppresor T cells slow down the immune system when the infection is gone.
• Chemicals such as cytokines and chemokines are released by the infected cells inorder to trigger the immune response.The steps include:
• Macrophages that engulfs the foreign antigen and displays on their surface.
• This activates the T cells.It proliferate and differentiate to form T cells and B cells.
• Phagocytosis of foreign body by the activated cells.

3):

• By the action of innate immunity two possible outcomes are inflammation and allergic reactions.
• When any foreign particle enters ,the body tries to pull it out through allergic reactions like sneezing,cough reflex etc.Inflammation is the first response of body to infection.
• If the pathogen has entered overcoming the first line defense,inflammation is produced as a result of the action of immune system.

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