Page 186 - PG 101-Course notes مذكرة النظري 24-25 with spec

Medicinal plants (PG 101) Level 1 Clinical Pharmacy-PharmD

Imbibition

Imbibition is defined as the displacement of one fluid by another immiscible fluid.

This process is controlled and affected by a variety of factors. The capillary number

and the mobility ratio have the greatest importance. It is also defined as the phenomenon

by which the living or dead plant cell absorb water by surface attraction.

• One example of imbibition that we can find in nature is the absorption of water by

hydrophilic colloids. Matrix potential contributes significantly to water in such
substances. Examples of plant material which exhibit imbibition are dry seeds before

germination. Imbibition can also entrain the genetic clock that controls
circadian rhythms in Arabidopsis thaliana and (probably) other plants.

• Different types of organic substances have different imbibing capacities. Proteins

have a very high imbibing capacity, starch less and cellulose least. That is why

proteinaceous pea seeds swell more on imbibition than starchy wheat seeds.

• Imbibition of water increases the volume of the imbibant which results in

imbibitional pressure. This pressure can be of tremendous magnitude. This fact can

be demonstrated by the splitting of rocks by inserting dry wooden stalks in the

crevices of rocks and soaking them in water, a technique used by early Egyptians

to cleave stone blocks.

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