1.The salt content in seawater is much higher than what we can process in the human body because sea water has a high concentration of salts (sodium chloride). The concentration of salt in the human body is about 75% less than you would find in seawater (Living Strong). Though living cells depend on sodium chloride (salt) to maintain the body's chemical balances and reactions, too much can be fatal. Dehydration would be a major concern because you would have to urinate more water than you're drinking in order to get rid of all of the excess salt from the seawater. The body needs at least 8 glasses or 64 ounces of water per day in order to ensure that our organs are receiving the proper amount of water. Without some form of desalination, the seawater that is consumed will have an adverse reaction to the human body. To be shipwrecked and only exposed to seawater would be considered a change in the external environment of our cells. 

Osmosis is defined as the movement of water across a semipermeable membrane in response to an imbalance of solute. If you were to consume nothing but salt water for two days, the osmotic pressure would begin to draw water from other parts of your body. Salt water is hypertonic to living cells, which would cause the water in our bodies to flow out of our bodies, and, since water is the essential ingredient in the human body, continuously ingesting seawater would be detrimental to your health and survival. Our blood cells will not be able to maintain physical integrity.
Seawater will not help you to survive in an emergency situation. The residual effects of prolonged exposure and consumption of sea water could result in the development of permanent brain damage. 

SOURCES:
National Ocean Service, Retrieved June 3, 2015. http://oceanservice.noaa.gov/facts/drinksw.html 
Living Strong, Retrieved June 3, 2015. http://www.livestrong.com/article/156036-what-are-the-side-effects-of-drinking-sea-water/
OLI. Retrieved June 3, 2015, Unit 4:The Cell; Module 22 Membrane Transport: https://oli.cmu.edu/jcourse/webui/syllabus/module.do?context=1b0fc6d980020ca6016389b1683c425e
Ocean Health, Chemistry of Sea Water. Retrieved June 3, 2015: http://oceanplasma.org/documents/chemistry.html 
Science Clarified. Retrieved June 3, 2015: http://www.scienceclarified.com/everyday/Real-Life-Chemistry-Vol-2/Osmosis-Real-life-applications.html#ixzz3c2bW6tPf
2. I can only imagine being out in the middle of the ocean for two days with the sun coming down full force and being extremely thirsty.There have been many occasions where I have swallowed salt water while spearfishing. Swallowing the water only made me dehydrated and thirst for fresh cold water. I now know before I go into the water to start fishing my cells are in a isotonic state. The concentration of salt and water is the same inside and outside my cells. During my time out fishing I accidentally swallow salt water. I often find myself adjusting my mask and take in more water and water also gets into my eyes. Before entering the water my cells were in an isotonic state and just the opposite happens when I swallow salt water during my fishing out in the ocean. The salinity outside my cells only keeps increasing while my cells release water instead of absorbing. I almost imagine myself as a graphic. My body acts as the cells in the graphic and my wetsuit acts as the cell membrane. My cells are slowly releasing water yet Im surrounded by salt water myself. Its a battle I will not win unless I go back to shore and start drinking salt water to start the regulation process. 
References
http://globetrooper.com/notes/why-cant-we-drink-sea-salt-water/
OLI Unit 4. The cell; Module 22 Membrane Transport.https://oli.cmu.edu/jcourse/webui/syllabus/module.do?context=1b0fc6d980020ca6016389b1683c425e