A victim of a shipwreck is left floating on a raft for days in the middle of the ocean.?

Question

A victim of a shipwreck is left floating on a raft for days in the middle of the ocean. Trying to quench his thirst, he drinks some of the salt water but finds that he gets thirstier. If he continues to drink more of the ocean’s water, he will actually become severely dehydrated. Explain why this is

Answer 1

It has to do with osmosis. Water molecules like to stick to other things dissolved in water, so if there's a place for them to go with lots of dissolved things, they will.

On land, most of the water that's around is relatively pure (rain, rivers, and the like). In the ocean, it can sometimes have so much salt that it's not possible to dissolve any more in it. Creatures in these environments are adapted to these conditions from their cells all the way up to organ systems.

And putting them in a different environment causes water to flow the wrong way! People who drink salt water actually have water sucked out of them so it can be near the salt. And salt-water fish who swim into fresh-water lakes find themselves overhydrated and can die from that.

Bottom line: Don't try this at home! ( :

Answer 2

Okay this is because of hypertonic diffusion. There are more salt in the water than in the cells. So its natural for water to move from high to low concentration. The osmotic pressure causes water to flow out of the cell. If enough water is removed in this way, the cytoplasm will have such a small concentration of water that the cell has difficulty functioning.

So you have the water leaving the cell and the cell shrinks so get more thirsty.