What makes our body temperature up when we have fever ? why we feel the heat !! thanks...SANAT.?

Peter is right that it is the body increasing it's temperature set point. But this is not all. When the body detects a bacterial or viral invader and begins to lyse the antigen, pyrogens are released which reach the hypothalmus. The hypothalmus is response to this increases the bodies set temperature and we begin to get hotter. The heat is generated as a defense mechanism so that a) our immune cells speed up their chemical reactions to break down the antigen and b) so that it provides the antigen with an inhospitable environment.The hypothalmus upregulates the autonomic nervous system and increases the temperature through vasoconstriction, increased heart rate, diversion of blood to the muscles, and increase metabolism in the body. The cells in our body can tolerate higher temperatures than many bacteria/viruses so this is an effective defense to some extent in keeping the spread of an organism down.

because most micro-organisms that infect our bodies cannot deal well with high temps, the body raises the temperature in order to kill it.

hi :) Fever is caused by an elevation in the thermoregulatory set-point, causing typical body temperature (generally and problematically considered to be 37 °C ±1 °C, or approximately 99 ±2 °F; see below for specifics) to rise, and effector mechanisms are enacted as a result. A feverish individual has a general feeling of cold despite an increased body temperature, and increases in heart rate, muscle tone and shivering, all of which are caused by the body's attempts to counteract the newly-perceived hypothermia and reach the new thermoregulatory set-point.

The set point for body temperature in the thermoregulation centre in the hypothalamus is raised in order to speed up the body's response and the body temperature is raised so we feel hotter.

Well, the others are right... I think...