සිංහල.‎ > ‎

Do we have blue blood in the veins?

posted Oct 28, 2015, 4:19 PM by Upali Salpadoru   [ updated May 26, 2016, 1:36 PM ]


Fig.There is nothing blue in the circulatory system.
The answer is 'Definitely No'.  
Oxygenated blood is cherry red while deoxygenated blood is dark red. Then why do the veins appear blue?  Light getting reflected from the veins passing throgh the fat layers and skin loose the red light rays while more blue light can pass through. 



Why do we add water to cook yams and rice?

There are two main reasons for this.
1. The main reason is to control the temperature. The temperature of water can nevrer go above 100 C in an open vessel at sea level. If you are living on a highland it will be evn less.  This is called the boiling point of water and is fairly constant. Perhaps if you close the pot the temperature can go up. This is what happens in a pressure cooker.
Boiling is really a water bath method of maintaining a constant temperature.

2. The other reason for using water is,  the food becomes soft and tastier when some water has been absorbed.
 
Instead of water, sometimes oil is used for a much higher temperature  cooking. As oils are mixtures and not a pure chemical like water, there is no definite boiling point. Yet we know that oils boil at a much higher temperature than water.

Comments