science agalaya

  C. Cellular Factors  Natural immunity is provided by the following cellular factors:  1. Phagocytosis  2. Natural killer cells (NK cells).  1  .Phagocytosis  Phagocytosis is a process of "cell eating" (GK - phagia- eating, cytos - cel . The phagocytic cells were discovered by Metchnik - off (1838).  They are two types, namely microphages and macrophages.  These are the profession phagocytes.  On some occasions, other cells also perform the f ction phagocytosis.   The microphages are the polymorphonuclear leukocytes (PMN).  It include neutrophils,basophil and eosinophils.  These are the dominant white cell the blood stream. These cells possess multilobed nuclei. They do not divide are short lived.  (Semen - The secretion of the testis, consisting largely of  sperms.)   The macrophages are the cells of the "mononuclear phagocytic system" which was originally called the "reticulo - endothelial syste...

  B. Biochemical Factors  The following biochemical factors are employed to fight against infectious organisms:  1. Secretions of the skin  2. Secretions of the digestive tract  3. Human milk  4. Nasal secretion and saliva  5. Lysozyme  6. Interferons  7. Complement  8. Properdin  9. Secretions of bacterial flora  10. Semen  11. Acute phase proteins.  1. Secretions of the Skin   The high concentration of salt in the sweat possesses bactericidal activity.   The acidity of sweat and thereby low pH (pH - 5.5) has microbicidal effect.   The secretions of the sebaceous and sweat glands act as antiseptics as they contain lactic acid and fatty acids which have bactericidal and fungicidal properties.   But certain areas of the body, namely, soles of the feet are deficient of sebaceous glands and thereby these areas are more attacked by fungal growth and hence such areas are sometimes re...

 Immunity  Highlights Immunity is the resistance to infection.   The immune system scans the body for pathogens.  It fights against the pathogens.   The immunity is of two types, namely:  Innate immunity  Acquired immunity or  Adaptive immunity.   The natural, inherited defense is innate immunity,  Example;   Skin as barrier, Fever,Coughing, Tears  Colostrum ,NK cells ,Sweat, Phagocytosis, etc.   1.The resistance developed during ones life time is called acquired or adaptive immunity.   2.It may be active or passive.   Example:  Humoral immune response  Cell mediated immune response  Vaccination  Immunological memory, etc.  Types of Immunity  Immunity is broadly classified into two types, namely: 1. INNATE IMMUNITY. ( non- specific or natural or native) 2.ACQUIRED IMMUNITY.(specific or adaptive)    Active (1.natural, 2. Artificial)  P...