3/26/99

Microbiology II

 

The digestive tract and Organs of the immune system

·        Bone marrow--75% hemopioetic; 25% immunopiotic tissue (precursor, T-cell, B-cell)

·        Thymus

·        Bursa equivalent organ

·        Cells-lymphocytes (T&B)

·        Granulocytes, basophils, eosinophils, neutrophils, macrophages

·        Peripheral organs

·        Lyphamtic system--lymph nodes

·        Reticuloendothelial system

·        Spleen, kidney, lungs, liver, peyer's patches

·        Thymus gland--composed of 2 lobes each made of lobules made of highly secretory cells

·        Thymosin--low MW (12,000D) protein

·        The gland is responsible of maturation of immune system

·        As child grows more and more, thymus cells become mature

·        Baby also gets immunity from ab's from mother

·        In thymectomized animals, injection of thymosin only temporarily allows for growth and life therefor need the gland itself

·        After 16-17 yrs, thymus gland begins to shrivel

·        By 50y/o nonfxnal

·        At birth,thymus weighs 15-20g

·        At 16-17y/o thymus weighs 60g

·        Lymph nodes

·        The "police stations of the bod"

·        Reticuloendothelial systems--filters

·        Nodes have B-cell (follicles and germinal centers)areas and T-cell areas (medulary and paracortical areas)

·        Function

1.      Destruction of invading microbes w/help of macrophages (90-95%)

2.      Processing of antigen--complexing of antigen w/RNA w/in macrophage

3.      Transfering of antigen to proper cells (B-cells) w/involvement of T-cells

4.      Maintain purity of blood (filtering organ)

·        When node fails to function becomes inflamed resulting in bacteremia or septicemia