Does a blown head gasket cause you to have no heat?

If the coolant system is full, the heater should still work. However, if the head gasket leak is really bad, it will be impossible to keep full, plus the exhaust bubbling through the coolant could airlock the heater core circulation. The engine is pretty much ruined if its been driven with this kind of problem for more than a couple days - it isn't cooled right and the water in the oil wrecks lubrication. This is a pretty general question - hard to answer - but have someone check it out.