ABSTRACT
T h e variou s tissue s an d organ s o f th e organis m ar e connecte d wi t h th e outsid e
environment a s wel l a s wi t h eac h other , throug h circulation , and i t i s throug h
the med iu m o f bloo d tha t nutrient s ar e transporte d to cell s a n d wast e product s
are removed . Th e genera l compositio n o f bloo d remain s remarkabl y constan t
despite th e fac t tha t numerou s biochemica l substances an d cellula r e lements ar e
constantly leaving and entering it. Thi s stead y stat e is maintained by biochemical
and physiologi c regulator y processes tha t result in equal rates of destructio n an d
formation, o r output an d input, o f cellular elements and biochemical substances .
