Why do we lose our sense of taste when we have a cold?

Our sense of smell in responsible for about 80% of what we taste. The tastebuds present on our tongues are limited to only the basic sensations: sweet, salty, sour, and bitter. All other flavours that we experience come from smell. This is why, when our nose is blocked, as by a cold, most foods seem bland or tasteless. Our sense of smell can normally detect up to 10,000 smells.