Intracellular phase digestion

In a review of feeding and digestion in the Bivalvia [37], it was proposed that the accumulation of metal-bound particulates in the digestive gland was a two-phase process reflecting extracellular and intracellular digestion, and Viarengo [87] has reached similar conclusions. In a pulse chase study of the uptake of radiolabelled metals (Ag, Cd, Cr, Hg, Se) by the zebra mussel Dreissena... 

An interesting outcome of the observed depuration patterns was that there could be a two- or three-phase process. This were interpreted as indicative of extracellular followed by intracellular digestion [95], A possible third phase might be due to metabolic loss of metals. 

Endocytosis involves the ceUular uptake of exogenous molecules or complexes inside plasma membrane-derived vesicles. This process can be divided into two major categories (1) adsorptive or phagocytic uptake of particles that have been bound to the membrane surface and (2) fluid or pinocytotic uptake, in which the particle enters the cell as part of the fluid phase. The solute within the vesicle is released intracellularly, possibly through lysosomal digestion of the vesicle membrane or by intermembrane fusion (Fig. 3.4). 

Life cannot be sustained without water. Water constitutes 45-73% of total human body weight. It is distributed in intracellular (55%) and extracellular (45%) compartments and provides a continuous solvent phase between body compartments. As the biological solvent, water plays a major role in all aspects of metabolism absorption, transport, digestion, and excretion of inorganic and organic substances as well as maintenance of body temperature. The unique properties of water are due to its structure. 

Digestion and absorption of lipids involves the coordinated function of several organs but can be divided into three phases luminal, intracellular, and secretory. 

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