Question

When a mosquito bites a body part, why does it swell up and starts to itch?

Answer 1

It is the female mosquito which bites just to suck blood from a person's body as a part of their eating and breeding habits. When a female mosquito bites she also injects saliva and anticoagulant into the blood, the chemical present in the saliva of female mosquito acts as a foreign particles to person's active immune system. So, when the person scratch anywhere on his body . the immune system released histamines from the mast cells in response to the local reaction. This acts as a natural process of inflammation leading to itching and swelling of the skin.