If I put my laptop on my lap and block the air vents, wouldn't this be bad for the computer?

My laptop has several air vents on the bottom. If I actually put my laptop on my lap, I would be blocking the air vents. Might this cause overheating problems?

But aren’t laptops designed to be used on laps? What’s the answer to this dilemma?

(I usually put the machine on a desk or other solid surface and prop up or raise the back for ventilation. But sometimes for convenience, I need to put it on my lap.)