Why can’t we drink sea water?

 We all need food, water and air to live. A major part of our body cells is made of water. If a person does not drink the water required to keep the balance of water inside the body, the resultant dehydration may kill him.

There is more water than land on the surface of the earth. But the huge amount of seawater on the earth cannot be used directly for drinking by us. Not only because it will taste salty, but also because it will have a bad effect on our bodies.

In our body, a natural process called ‘osmosis’ helps liquids pass through the thin walls of body cells. Normally, the water that goes to the cells is lighter than the water that is already present inside them, so it passes through the cell walls and enters the cells.

 But if salt water reaches these cells the water from inside the cells joins this salt water instead of allowing it to enter the cells. Thus the cell becomes even drier by losing water.

A thirsty person after drinking salt water actually makes his body thirstier. People travelling on a ship have to carry their drinking water with them because even if they are surrounded by water from all sides they cannot drink it to quench their thirst!

What causes allergies?

Some people are sensitive to certain substances such as some particular food items, animal hair, plant pollen, chemicals, dust, or almost anything on earth. These may enter a person’s body when one eats inhales or touches them.

 When any of the substances don’t “agree” with the person’s body system he feels uncomfortable or even sick. Hay fever, skin rash, some types of asthma, and reactions to certain medicines and injections are some of the more commonly seen forms of allergies.

Human bodies have been provided with certain ‘power’ to fight infections and illnesses. When some harmful infection enters the body, certain cells in the body begin to produce chemicals called “antibodies” to fight it.

When a person is allergic to a certain substance, a similar reaction takes place inside the body cells, that is, they start producing antibodies. And in the process, unpleasant reactions – fever, rash itching fluctuation in blood pressure, breathing problems etc. – are produced.

This happens because the antibodies combine with the foreign substance and produce other chemicals, called “histamines”. These histamines disturb the muscle membranes, blood, lungs, skin, or other body organs.

Scientists have developed drugs that can be used to treat allergies of different types and these are called antihistamines because they block the activity of histamine. But it is still not explained why one person is allergic to one thing and not the other!