Question

1. List and explain a minimum of four different defense mechanisms at the cellular levels?

Answer 1

Ans. Cellular barriers includes :-

1.Natural killer cell :- it is large granular lymohocyte.during this process apart from the phagocytes,another type of cells called natural killer cells kill virus infected cells and tumour cells of the body by creating perforin lined pores in the plasma membrane of target cells ( i.e. infected cell ).water enters through these pores causing sweelling and bursting of the diseased cells.

2.Neutrophils :- also known as polymorphs have fine or small granules in the cytoplasm.neutrophills play an important role im the defense mechanism of the body.

Neutrophils secrete substance like

a)Proteases,myeloperoxidases,elastases,metalloproteinases

Action- destruction of microorganisms

b) defensins - action anti microbial action,anti inflammatory action,wound healing,chemotaxis

c)cathelicidins - action antimicrobial action

3.monocytes :-it play an important role in defence mechanism along with neutrophils,these leukocytes provide the first line of defense.monocytes secrete:

a)Interleukin ( IL - 1) :- action- acceleration of inflammatory response.destrution of invading organisms

b)chemokines :- action - chemotaxis

c) colony stimulation factor and platelet activating factor.

4.Mast cell :- Mast cells are a type of innate immune cell that reside in connective tissue and in the mucous membranes. They are intimately associated with wound healing and defense against pathogens.