Your immune system if why you feel ghastly when you catch a cold


Idan Ben-barak For The Daily Mail

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An astounding number of germs lurk invisibly everywhere we look or touch

An astounding number of germs lurk invisibly everywhere we look or touch: on door handles, computer keyboards and kitchen counters.

With all these disease-causing bugs around us, you might be excused for thinking it’s a wonder any of us are still alive. Well, it is a wonder: a wonder called the immune system.

We have multiple layers of defence against illness – from ‘good’ bacteria in the gut, to ‘memory’ cells that remember diseases we’ve had.

This intricate system operates silently in the background, only becoming noticeable when things go seriously wrong. Here are seven ingenious things you didn’t know about your immune system . . .

WHY YOU FEEL ROTTEN WHEN YOU’RE ILL

Often when we have an infection, the invading viruses or bacteria aren’t all that harmful – it’s the immune system’s overreaction that is the major cause of our symptoms.

Consider the cold virus. It’s actually one of about 200 different kinds of virus, which all cause similar symptoms such as a sore throat and sneezing.

But the cold viruses themselves contribute almost nothing towards these symptoms: they’re the result of the inflammatory response by your immune system. Inflammation occurs when immune cells send chemical distress signals to recruit more resources to fight the infection.

Blood vessels near the infection site become more permeable, allowing more cells and substances to flood the area. This means there is suddenly more aggressive stuff intent on killing the virus. For us, this means a blocked nose or sore throat, because that’s where the virus tends to hang out. The inflammation also irritates the nose, making you sneeze.

WHY SOME BUGS LAY YOU LOW FOR DAYS

Many bugs are eliminated by the immune system minutes after entering the body. When the pathogen (any micro-organism that can cause disease, such as a virus or bacteria) enters the body, a cocktail of enzymes and antimicrobial molecules try to attack it.

First, proteins known as the complement system stick to the intruder’s surface and try to kill it. If this doesn’t work, bacteria-gobbling cells called phagocytes try to swallow the pathogen whole, digesting it with chemicals.

Often, this is enough to bring an infection under control in a couple of hours. This system is called the innate immune system.

The adaptive immune system tailors its response to the individual infection. This takes days to take action

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