Question

• Innate immunity:
  • First line defenses: List three physical and three chemical defenses and describe how they defend your tissues from invasion by pathogens.
  • Second line defenses: Name three ways your innate immune system responds to invasion by pathogens and how they help fight infection.
• Adaptive immunity: Humoral
  • Describe how B cells are activated.
  • List and describe the how antibodies help clear an infection.
• Adaptive immunity: Cell mediated
  • Describe how T cells are activated
  • Describe how T cells help clear an infection.

Answer 1

The immune system includes three lines of defense against foreign invaders like physical,chemical barriers,non specific resistance and specific resistance. *The first line of defense are the physical and chemical barriers,which are consider as innate immunity. *Second line of defense is nonspecific resistance,it is also a function of innate immunity. *The third line of defense is specific resistance,which is considered as function of acquired immunity.

Innate immunity:Is nonspecific immune defense mechanisms that activate immediately or with in invasion of the the body .Innate immunity is present at birth.It is activate when immune system recognizes chemical properties of the antigens. Acquired immunity:It is also called as specific immunity or adaptive immunity,it is not present at birth but it is learned.The immune system encounter's antigen and the acquired immunity components learn how to attack each antigen and develop a memory for it. Example :At birth we will give BCG vaccine with antigen of mycobacterium,then our immune system learn this antigen develop resistance to particular antigen,it will in prevention of TB in future years of life.

First line defense:

Physical Barriers in our body for any antigens are skin,mucous members,hair,cilia,urine. Skin:It us a thick layer of dead cells in the epidermis provides a physical Barrier to microorganisms. As the epidermis sheds,microbes which present on skin also removed by shedding . Mucous membrane: These membranes produce mucous to trap microbes so they cont spread to the rest of the body. Cilia :These are very fine hair like structures,lining wind pipe, helps in moving mucus and traps particles away from lungs.

Chemical barriers are tears,gastric juices,saliva with enzymes,sebum,hyluronic acid. Tears:Tears produce an enzyme called lysozyme,this enzyme break down the cell wall and acts as antibiotic for killing bacteria. Gastric acid:By its acidity it kill's the bacteria. Sebum :It is unsaturated fatty acid provide protective film on the skin and inhibits growth.

Second line if defense: Mechanisms of defense in innate immunity destroy invaders in the general way and do not target specific antigen .Some of these mechanism are phagocytes ,inflammation,fever. *Phagocytes ingest and destroy microbes that entre into body tissues. *Inflammation: Inflammation occurs when white blood cells accumulated on area of invasion by microbes,this response include swelling,redness heat and pain.

Third line of defense is Acquired immunity or specific resistance,it is acquired by antigen learning by body cells. Specific White blood cells are responsible for this.T cells and B cells. A specific immune response occur when antibodies are produced by B cells, it is called humoral immunity. Antigen specific antibodies are produced by B cells. T cells give cell meditated immunity.it dose not involve antibodies,it activates phagocytes,antigen specific cytotoxic T lymphocytes and release of various cytokines in response to antigen.